Agricultural Economics Report No. 432
December, 1999
The Feasibility of Wetland Restoration to Reduce
Flooding in the Red River Valley: A Case Study of
the Maple (ND) and Wild Rice (MN) Watersheds
Steven D. Shultz
Department of Agricultural Economics
Agricultural Experiment Station
North Dakota State University
Fargo, North Dakota
Acknowledgements
Funding was provided by the Red River Basin Task Force of the International Joint
Commission (IJC), the North Dakota State Water Commission, the Minnesota Department of
Natural Resources, and the Agricultural Experiment Station at North Dakota State University.
Much of the research reported here is closely related to, and dependent upon, the work of
others. Melanie Bengtson and Pad (G. Padmanabhan) from the Civil Engineering Department at
NDSU estimated hydrologic models to quantify the relationships between wetland storage and
flooding in the Maple and Wild Rice Watersheds. And, Mike Kjelland, for his MS Thesis in the
Department of Agricultural Economics at NDSU, quantified flood-related damage over time in
the two watersheds. Dr. Jay Leitch at NDSU was involved in all aspects of the IJC research and
provided substantial assistance and input into this research project.
I would also like to thank various faculty members, students, and staff in the Department
of Agricultural Economics at NDSU for their help and assistance. In particular, Kevin Kermes
and Pat Fridgen for compiling land rental data and making maps, and to Dave Lambert and Carol
Jensen for helping to review and prepare this document.
I would also like to thank Curtis Borchert of the Norman County (MN) Soil and Water
Conservation Board for providing GIS data, the Wild Rice Watershed District for providing
watershed information, Moore Engineering of Fargo for providing data on the Maple Watershed,
and to Brett Hovde at the North Dakota State Water Commission for providing information
about the Devils Lake impoundment-storage program.
Any errors or omissions in the report are the sole responsibility of the author.
We would be happy to provide a single copy of this publication free of charge. You can
address your inquiry to: Carol Jensen, Department of Agricultural Economics, North Dakota
State University, P.O. Box 5636, Fargo, ND, 58105-5636, Ph. 701-231-7441, Fax 701-231-7400,
e-mail [email protected] . This publication is also available electronically at this web
site: http://agecon.lib.umn.edu/ndsu.html
NOTICE:
The analyses and views reported in this paper are those of the author. They are not necessarily endorsed by
the Department of Agricultural Economics or by North Dakota State University.
North Dakota State University is committed to the policy that all persons shall have equal access to its
programs, and employment without regard to race, color, creed, religion, national origin, sex, age, marital status,
disability, public assistance status, veteran status, or sexual orientation.
Information on other titles in this series may be obtained from: Department of Agricultural Economics,
North Dakota State University, P.O. Box 5636, Fargo, ND 58105. Telephone: 701-231-7441, Fax: 701-231-7400,
or e-mail: [email protected].
Copyright © 1999 by Steven D. Shultz. All rights reserved. Readers may make verbatim copies of this
document for non-commercial purposes by any means, provided that this copyright notice appears on all such
copies.
Table of Contents
Page
List of Figures and Tables.............................................................................................................ii
Highlights
..............................................................................................................................iii
Abstract
..............................................................................................................................iv
Chapter 1: Introduction.................................................................................................................1
Chapter 2: Literature Review and Background Information........................................................4
2.1
2.2
2.3
2.4
The Maple River Watershed ......................................................................................4
The Wild Rice River Watershed ................................................................................7
Historical Flood Damage in the Watersheds..............................................................8
The Hydrologic Modeling of Wetland Storage and Flooding..................................16
Chapter 3: The Feasibility of Wetland Restoration-Storage Programs......................................21
3.1
3.2
3.3
3.4
3.5
Quantities and Locations of Previously Drained Wetlands .....................................21
The Costs of Wetland Restoration-Based Storage Programs...................................22
The Potential Benefits of Wetland Restoration-Storage Options.............................29
Net Present Values and Benefit-Cost Ratios of Wetland Restoration Options........30
Wetland Restoration Feasibility Considering Additional Benefits of Wetlands......30
Chapter 4: The Feasibility of Impoundment-Storage Programs ............................................... 37
4.1 An Introduction to Impoundments for Flood Control..............................................37
4.2 The Feasibility of Impoundment Storage in the Maple and
Wild Rice Watersheds.........................................................................................38
Chapter 5: Summary and Conclusions.......................................................................................43
References
.............................................................................................................................45
Appendices
A: Abbreviations Used in the Report .............................................................................48
B: Impoundment-Storage Programs in North Dakota and Minnesota ...........................49
List of Figures and Tables
Figure
1
2
3
4
5
6
7
8
9
10
11
Page
Study Site Location: Watersheds within the Red River Valley ........................................2
Land Use in the Maple Watershed ....................................................................................5
Wetland Types in the Maple Watershed ...........................................................................6
Land Use in the Wild Rice Watershed..............................................................................9
Wetland Types in the Wild Rice Watershed ...................................................................10
Historical Flood Damage in the Maple Watershed .........................................................13
Historical Flood Damage in the Wild Rice Watershed...................................................14
Residential Flood Damage by Township in the Wild Rice Watershed...........................15
Drained Wetlands and Hydrology, Maple Watershed ....................................................23
Drained Wetlands and Hydrology,Wild Rice Watershed ...............................................24
Dollars Per Acre for Water Storage on Croplands in the Wild Rice Watershed ............27
Table
1
2
3
4
5
6
7
8
9
10
11
12
13
Page
Flood Damage and Characteristics, Maple Watershed (1989-1998) ..............................12
Flood Damage and Characteristics, Wild Rice Watershed (1989-1998) ........................12
Effects of Wetland Storage in Reducing Peak Flows During Flood Events
in the Maple River at Enderlin, ND ................................................................................17
Wetland Acres by Size Classes in the Maple and Wild Rice Watersheds ......................22
Wetland Restoration Costs in the Maple and Wild Rice Watersheds
Over a 20-year Period .....................................................................................................28
Historical and 20-Year Expected Reductions in Flood Damage Due to
Wetland Storage in the Maple Watershed.......................................................................31
Historical and 20-Year Expected Reductions in Flood Damage Due to
Wetland Storage in the Wild Rice Watershed.................................................................32
Benefit-Cost Ratios of Alternative Wetland Restoration-Storage Options in
the Maple and Wild Rice Watersheds.............................................................................33
Required Reductions in Peak Flood Stage and Flood Damage for
Alternative Wetland Restoration-Storage Options to Break Even..................................34
Required Values of Other (Nonflood-Related) Wetland Benefits in Order
for Wetland Restoration with Full Environmental Services to be Feasible ....................36
Cost of Impoundment Storage in the Maple and Wild Rice Watersheds........................39
Historical and 20-Year Expected Reductions in Flood Damage Due to
Impoundment-Storage in the Maple Watershed..............................................................41
Historical and 20-Year Expected Reductions in Flood Damage Due to
Impoundment Storage in the Wild Rice Watershed........................................................42
ii
Highlights
The economic feasibility of wetland restoration and the use of impoundments to store
water and reduce flood damage, were evaluated in two Red River Valley watersheds: the Maple
River Watershed in North Dakota and the Wild Rice River Watershed in Minnesota.
The economic evaluations utilized information from past and concurrent hydrologic
modeling and wetland restoration studies, National Wetland Inventory data, local land rental
values, and site-specific historical flood damage.
Three wetland restoration options were evaluated in each watershed: simple restoration
(one foot of available storage ‘bounce’ per surface acre), restoration with outlet control devices
(two feet of bounce), and full restoration providing a full range of wetland-based environmental
goods and services and with two feet of bounce. For each alternative, the use of average and
lower-end (cheaper) land rental rates was evaluated. Finally, a highly optimistic scenario was
evaluated where the least expensive alternative (simple restoration on cheap land) was
hypothesized to provide two feet of storage bounce.
Economic feasibility was evaluated through benefit-cost ratios calculated for a future 20year period. Costs included land rentals, and restoration and construction costs, which varied by
type of restoration and as a function of wetland size. Benefits (reduced flood damage) for a
hypothetical 20-year future period were based on historical flood damage (1989 to 1998) both
within and downstream of the watersheds along with hydrologic modeling estimates of
reductions in peak flood stage with alternative storage scenarios and flood events in the Maple
River Watershed (Bengtson and Padamanabahn, 1999).
None of the wetland restoration options were found to be economically feasible in
reducing flood damage in either of the two watersheds. Benefit-cost ratios ranged from 1:1.4 for
the most optimistic scenarios, to 1:4.1 for restoration with the provision of full environmental
services. Reductions in peak flood stage and damage would need to be reduced from 3.4% to
10.2% for different wetland restoration options to break even.
The inclusion of additional (nonflood-related) wetland values did not make wetland
restoration economically feasible. However, these additional wetland benefits have the potential
to improve the feasibility of wetland restoration-storage activities, especially at the local (sitespecific) level. More research in this area is warranted.
Finally, the use of impoundments to store water and reduce flood damage in the two
watersheds was evaluated. Impoundments can store more water at a cheaper cost than wetlands
but they do not provide many additional goods and services. With benefit-cost ratios which
ranged from 1:1.1 to 1:1.7, impoundments are also not considered economically feasible.
In conclusion, neither the restoration of wetlands nor the construction of impoundments
on a large scale, are likely to be an economically feasible way to reduce flood damage in the Red
River Valley. However, future research is warranted with respect to the use of impoundment
storage on a site-specific basis and the calculation of the nonflood-related benefits of restored
wetlands.
iii
Abstract
The economic feasibility of wetland restoration and the use of impoundments to store
water and reduce flood damage were evaluated in two Red River Valley watersheds: the Maple
River Watershed in North Dakota and the Wild Rice River Watershed in Minnesota. The
economic evaluations utilized information from past and concurrent hydrologic modeling and
wetland restoration studies, National Wetland Inventory data, local land rental values, and sitespecific historical flood damage. None of the wetland restoration options were found to be
economically feasible in reducing flood damage in either of the two watersheds. Benefit-cost
ratios ranged from 1:1.4 for the most optimistic scenarios, to 1:4.1 for restoration with the
provision of full environmental services. Reductions in peak flood stage and damage would
need to be reduced from 3.4% to 10.2% for different wetland restoration options to break even.
The use of impoundments was also found not to be an economically feasible method in reducing
flood damage. Future research is warranted with respect to the use of impoundment-storage for
flood control on a site-specific basis and the calculation of the nonflood-related benefits of
restored wetlands.
Key Words: wetland restoration, flooding, Red River Valley
iv
Chapter 1. Introduction
Steven D. Shultz∗
Flooding in the Red RiverValley (RRV) has historically caused large-scale physical and
economic damage to public and private property. There is wide consensus that new strategies
are needed to improve the prediction, control, and mitigation of future flood events (IJC, 1997).
However, there is a great deal of uncertainty and disagreement regarding the most efficient ways
to reduce flood damage.
There has been considerable speculation and debate regarding the relationships between
wetlands and flooding in the RRV. On one side of the issue are those who believe that wetlands,
by storing water, can effectively reduce flood impacts and that the wetland drainage in the last
century has exacerbated recent low frequency flood events (Sierra Club, 1997 and 1998). Others
believe that wetlands have no significant impacts on floodwater levels in the RRV, especially
during larger (low frequency) flood events during the early spring when wetlands are already
full.
This present study will evaluate the economic feasibility of restoring previously drained
wetlands to reduce downstream flood damage both within and on the main-stem of the RRV.
This will include an evaluation of ‘simple’ wetland restoration (primarily for flood control), and
more ‘complex’ restoration efforts that include the construction of outlet control devices and the
restoration of a full range of wetland-based environmental goods and services.
A secondary objective is to evaluate the economic feasibility of establishing
impoundments (earthen dikes, constructed in agricultural fields with outlet control devices) for
storage in order to reduce downstream flood damage both within sub-watersheds and on the
main-stem of the RRV. Many of the same doubts and uncertainties concerning the effectiveness
of wetland storage to reduce downstream flooding exist for impoundment-storage projects.
However, impoundment-storage programs have already been initiated in the nearby Devils Lake
area of North Dakota and the Wild Rice Watershed of Minnesota.
This study will focus on two RRV Watersheds: the Maple River Watershed in North
Dakota and the Wild Rice River Watershed in Minnesota which are located west and northeast of
Fargo/Moorhead and south of Grand Forks/East Grand Forks (Figure 1). They are typical RRV
watersheds, dominated by agricultural land use and with large acres of both existing and drained
wetlands, and with frequent spring flood events.
∗
Assistant Professor, Department of Agricultural Economics, North Dakota State University, Fargo.
Figure 1. Study Site Location: Watersheds within the Red River Valley.
Watersheds in the Red River Basin
Alternative wetland restoration and impoundment options are evaluated only for the
middle to upper reaches of the two watersheds (hereafter referred to as the upper watershed) for a
variety of reasons. First, most of the recently drained wetlands identified by the National
Wetland Inventory (NWI) are located in the upper sections of the watersheds (93% in the Maple
and 74% in the Wild Rice). Second, land values in the upper watersheds are lower. Finally, a
previous hydrological-based study of the same watersheds (based partly on simulated data),
found that upper wetland storage in contrast to wetland storage in the middle and lower reaches
of the watersheds provided the greatest reductions on streamflows (Meyer, 1998).
Evaluating the feasibility of wetland restoration and impoundment options to reduce
flood damage in these two watersheds involves three distinct components. First, the costs of
alternative wetland restoration options and impoundment construction are determined. Second,
benefits associated with reduced flood damage both within and outside the watersheds are
estimated. Finally benefit-cost ratios under alternative scenarios are calculated.
The costs of restoring drained wetlands and establishing storage impoundments will be
estimated under various scenarios in the upper sections of the watersheds. Data for these
estimates are based on the NWI, local agricultural land prices, previously conducted wetland
2
restoration efforts (Sip, 1998 and Eppich et al., 1998), and the experiences of two ongoing
impoundment-storage projects in, and near, the RRV. Alternative types of restoration will be
evaluated, specifically simple wetland restoration, more complex restoration with outlet control
devices, and complete restoration that captures a full range of ecological benefits associated with
wetlands. It will be assumed that wetland construction costs are subject to economies of scale or,
more specifically, that per acre construction costs are lower for large wetlands.
The quantity of wetlands potentially available for restoration is based on wetlands
classified as ‘drained’ in the NWI database. It is likely that this database may under-represent
the actual quantity of drained wetlands in the watersheds, but this should not effect our
feasibility results, which are based on benefit-cost ratios. In other words, if the quantity of
wetlands available for restoration increases, it is assumed that associated benefits and costs will
increase proportionately. Regarding impoundments, it is assumed an equal quantity of land
available for wetland restoration is available for the construction of impoundments.
The potential benefits of alternative wetland restoration and impoundment-storage
programs are reduced flood-related damage resulting from the creation of wetland restorationand impoundment-based storage. Avoided flood damage is based on annual flood damage from
1989 to 1998, best estimates of available storage capacity or ‘bounce’ of wetlands, and the
hydrologic relationships between wetland storage and historical peak flood stage in the Maple
Watershed calculated in a concurrent study by Bengtson and Padmanabahn (1999). These
reduced flood damage benefits from 1989 to 1998 are then extrapolated to a hypothetical 20-year
time period in the future.
Benefit-cost ratios are used to measure the feasibility of alternative wetland restoration
and impoundment-storage options over a discounted 20-year period in the future. Finally,
required reductions in peak flood stage (and reduced flood damage), and minimum values of
nonflood-related wetland benefits required for alternative wetland restoration-storage options to
break even are estimated. These ‘what if’ estimates are intended to facilitate future evaluations
of the economic feasibility of wetland restoration based on improved hydrologic modeling
procedures and/or improved estimates of the values of wetland functions.
3
Chapter 2. Literature Review and Background Information
The physical and socioeconomic characteristics of the two sub-watersheds, which are the
focus of the study, are summarized below. This is followed by an evaluation of the historical
flood-related damage inside and just downstream of the watersheds, and a review of
hydrological-based models and related literature which forms the basis for many of the
assumptions used in this study.
2.1. The Maple River Watershed
The Maple River Watershed (hereafter referred to simply as the Maple Watershed) is a
sub-watershed of the RRV, located in eastern North Dakota, approximately in the geographic
middle of the RRV basin (Figure 1). The watershed transects parts of five counties (Steele,
Barnes, Cass , Ransom, and Richland), and 63 townships. Its total area is approximately
1,024,000 acres (1,600 square miles) and it contains 48 sub-watersheds (as classified by Moore
Engineering).
The Maple Watershed originates in the upper reaches of a five-county drainage area
(northern Richland, northern Ransom, southern Steele, northeastern Barnes, and northwestern
Cass counties). The Maple River flows southward through a well-defined valley between the
towns of Chafee and Enderlin. At Enderlin, the river changes direction and flows to the
northeast, meandering across the flat, RRV Plain. Approximately five miles to the north of West
Fargo, the Maple River joins the Sheyenne River.
Approximately 25% of the eastern watershed is classified as Glacial Lake Plain. Moving
west, the watershed rises out of the RRV. This transition area is classified as the Beach Ridge
Area and accounts for roughly 15% of the watershed. Glacial Lake Aggassiz fluctuated
throughout time, leaving distinct markings on the landscape in the form of beaches.
The western and northern portions of the upper watershed are to the west of the Beach
Ridge Area. This sub-basin area is characterized by rolling uplands and is developed on a
recessional moraine and accounts for approximately the remaining 60% of the watershed. The
landscape characteristics of this area were formed by the soil, rocks, and debris deposited by the
glaciers (Houston Engineering, Inc., 1999).
Land use in the Maple Watershed is influenced by its geophysical characteristics.
Agriculture predominates in the basin and the principal agricultural crops include wheat, barley,
oats, sugarbeets, potatoes, corn, beans, forage grasses, and sunflowers (see Figure 2). Wheat is
rotated with beans and potatoes and is planted mostly in the northern half of the basin while corn
and soybeans are planted mostly in the southern third of the basin.
Based on the NWI compiled by the United States Fish and Wildlife Service (USFWS),
within the Maple Watershed there are 48,342 acres of wetlands of which 2,900 are drained
(Figure 3).
4
Figure 2. Land Use in the Maple Watershed.
Source: National Agricultural Statistics Service.
5
Figure 3. Wetland Types in the Maple Watershed.
6
Prior to several U.S. Army Corps of Engineers (USACE) flood mitigation projects in the
late 1980s, flooding in the Maple Watershed occurred regularly in the city of Enderlin where the
Maple and South Branch Rivers converge (International Coalition, 1989). East of Enderlin,
waterflows have a high velocity until slowing greatly in the plains area north and east of
Leonard. In this flat, Glacial Lake Plain area, channel capacity decreases and the potential for
flooding greatly increases.
The Cass County Joint Water Resources District (CCJWRD) is currently evaluating
alternatives that may alleviate flooding in the watershed, particularly along the lower Maple
River. According to the 404 Permit for Maple River Dam Draft Environmental Impact
Statement (DEIS), water storage through main-stem dams, tributary dams, or wetland restoration
are the only alternatives that are both technically feasible and meet the purpose and need of the
project (USACE, 1998). Eleven plans were evaluated, with the preferred plan involving one
main-stem dam located downstream of Enderlin, approximately half way between Enderlin and
Leonard. This plan would protect 7,750 acres at a cost of $1,806 per acre protected.
2.2. The Wild Rice River Watershed
The Wild Rice River Watershed [hereafter referred to simply as the Wild Rice Watershed
(WRW)] is a sub-watershed of the Red River Watershed. It is located in northwestern
Minnesota, just south of the approximate mid-line of the RRV basin. The watershed transects 6
counties (Becker, Clay, Clearwater, Mahnomen, Norman, and Polk) and 86 townships with a
total area of 1,293,467 acres (2,021 square miles).
Approximately 25% of the western watershed is Glacial Lake Plain (lakebed region of
the Glacial Lake Aggassiz) and is nearly flat. Moving east, the watershed rises out of the RRV
in a transition area classified as the Beach Ridge Area, which accounts for roughly 15% of the
watershed. Glacial Lake Aggassiz fluctuated throughout time, leaving distinct markings on the
geography in the form of beaches. This Beach Ridge Area follows a north-south corridor
approximately eight miles wide (Houston Engineering, Inc., 1999).
The glacial moraine is to the east of the Beach Ridge Area and accounts for
approximately the remaining 60% of the watershed. The landscape characteristics of this area
were formed by the soil, rocks, and debris deposited by the glaciers (Houston Engineering, Inc.,
1999). Lakes, ponds, bogs, and wetlands dot the landscape. The terrain is gently rolling with
occasional steep grades.
In close parallel to the physiographic regions, there are three distinctive soil groupings in
the watershed (Houston Engineering, Inc., 1999). Clay soils primarily dominate the Glacial
Lake Plain in the western watershed. These soils are highly productive for agriculture, have low
permeability, and have poor internal drainage. The soils in the Beach Ridge Area are more
diversified, ranging from clay loams and sandy loams to sands and gravels. Clays and silts
essentially make up the glacial moraine. Drainage within the soils of this area varies from poor
to good.
7
Land use in the watershed is largely influenced by its geophysical characteristics.
Cropland predominates in the western basin, while the far eastern basin is largely forested.
Approximately 67% of the watershed is cultivated, 18% is forest, and 7% is in pasture (Figure 4
and IJC-NDSU, 1999). The principal crops grown are wheat, barley, oats, sugarbeets, potatoes,
corn, beans, forage grasses, and sunflowers.
Agriculture largely influences the economy of the western and central parts of the
watershed while tourism, lake cottages, and related recreational activities are a major part of the
local economy in the eastern part of the watershed which contains many lakes and forests.
Based on the NWI compiled by the USFWS, within the WRW there are 120,500 acres of
wetlands (Figure 5). In addition, there are 17,000 acres of drained wetlands and about 800
impounded acres. Within the upper watershed, there are about 100,000 total wetland acres,
12,600 drained acres, and 350 impounded acres. As discussed later, most of the drained
wetlands are associated with large-size wetlands (greater than 5 acres).
Flooding in the WRW usually occurs during April to June and occasionally in March and
July. Snowmelt is the primary contributor to flooding within the Wild Rice basin, with spring
rains often adding to the runoff. Saturated soil, frozen ground, and ice-covered rivers also
contribute to flooding. During the early stages of snowmelt, river channels are often clogged by
hard packed snow and ice which can increase local flood stages by several feet (USACE, 1980
and Kranz and Leitch, 1993).
Water flows are generally contained in definable areas of the upper watershed (USACE,
1980). Stream channels in the Beach Ridge Area generally are deeper and more defined with
water contained within stream banks. Channel capacity decreases upon entering the flat valley
plain resulting in overland flooding. The western portion of the lakebed region is subject to
regular flooding by the Red River of the North (Houston Engineering, Inc., 1999).
2.3. Historical Flood Damage in the Watersheds
Flood damage reports in the RRV have, for the most part, tended to be very general in
nature or they focussed on single flood events at a particular site (most often Fargo or Grand
Forks). Examples of such damage reports can be found in Krenz and Leitch, 1993; IJC, 1997;
and Carlson, 1999. Of relevance to this study is flood damage that has occurred both within the
Maple and Wild Rice Watersheds and damage outside the watersheds downstream of the mainstem of the Red River.
8
9
Figure 4. Land Use in the Wild Rice Watershed.
10
Figure 5. Wetland Types in the Wild Rice Watershed.
Flood Damage Within the Maple and Wild Rice Watersheds
The quantification of economic damage associated with flooding in the Maple and Wild
Rice Watersheds over time (from 1989 to 1998) was undertaken specifically to assist with this
present study. This required the collection, assembly, and modification of data under varying
assumptions, from local, state, federal and nongovernmental agencies (over 40 different agencies
and institutions in both the public and private sector were contacted). Of particular importance
were data obtained from the Federal Emergency Management Agency (FEMA). Agricultural
damage data from the USDA was not provided because it was not possible to separate floodrelated from other damage and assistance data. In many cases, data were reported to us only at
the county or regional level of analysis. In order to obtain needed flood damage data at the
watershed level of analysis, the following tasks were undertaken.
First, township-specific damage report data obtained from FEMA were manually
classified to identify in which counties and/or townships the damage was located. Second,
agricultural damage for the watersheds was estimated by manipulating and extrapolating the
‘Computerized Agricultural Crop Flood Damage Assessment System’ (CACFDAS) model
previously estimated by the USACE in the WRW and by a local engineering firm in the Maple
Watershed.
Third, county-level agricultural damage data occurring in a watershed were estimated by
dividing the total agricultural damage reported by individual counties by the percentage of the
county actually located in the watershed. These data were then compared and/or combined with
the previously modeled agricultural damage data.
Fourth, county-level flood damage expenditures by FEMA, insurance agents, agencies,
grants, loans, charity, etc., were divided by the percentage of the population of the county in a
watershed to determine watershed-specific damage.
Finally, flood damage data were estimated for years when they were not available based
on data from other years and annual flood volume data (peak flows and flood stages and duration
and antecedent moisture conditions).
Additional details concerning the estimation of historical flood damage in the watersheds
can be found in a recent Master’s thesis in the Department of Agricultural Economics at North
Dakota State University (Kjelland, 1999).
Annual flood damage (both total and agricultural only damage) are summarized in Tables
1 and 2. Agricultural flood damage makes up 55% and 39% of total flood damage in the Maple
and Wild Rice Watersheds, respectively (Figures 6 and 7). This damage is usually associated
with summertime floods that last several days or more. In contrast, residential flood damage is
most often associated with very large single event floods during the early spring. As expected,
residential flood damage (FEMA public assistance payments) tend to be concentrated in the
lower reaches of a watershed where higher concentrations of towns and people are located
(Figure 8).
11
During the ten-year period from 1989 to 1998, flood damage in the Maple Watershed
totaled approximately $29.3 million, while in the WRW total damage was $102 million (both in
1998 dollars). It should be noted that this 10-year period is part of a pronounced ‘wet cycle’ in
the region.
Table 1. Flood Damage and Characteristics, Maple Watershed (1989-1998)*
1989
1992
1993
1994
1995
1996
1997
1998
Total
Damage
$0.3
$0.1
$12.4
$0.5
$0.9
$1.8
$12.5
$0.8
($ millions)
Agricultural
Damage
64% 100% 62%
87%
52%
68%
10%
2%
(% of total)
Peak CFS &
981
710
3,770
3,040
1,830
3,860
4,060
1,730
Stage (ft)
8.4 ft 7.3 ft 12.7 ft 11.5 ft 10.1 ft 12.3 ft 12.6 ft
9.9
If Wet Prior
to Flood
No
No
Yes
No
Yes
Yes
Yes
Yes
Notes:
- At Enderlin, ND, the flood stage is at 9 feet.
- In 1990 and 1991, no serious flooding or flood damage occurred in the watershed.
Table 2. Flood Damage and Characteristics, Wild Rice Watershed (1989-1998)*
1989
1990
1993
1994
1995
1996
1997
1998
Total
Damage
$2.6
$0.6
$15
$2.1
$0.9
$3.3
$68.8
$8.7
($ millions)
Agricultural
Damage
60%
0%
72%
21%
0%
61%
12%
82%
(% of total)
Peak CFS &
5,480
1,100
3,680
2,600
3,200
5,750 10,600 6,550
Stage (ft)
29.6 ft 14.3 ft 27.2 ft 21.2 ft 25.3 ft 28.7 ft 33.9 ft 26.9 ft
If Wet Prior
to Flood
No
No
Yes
No
No
Yes
Yes
No
Notes:
- At Hendrum, MN, the flood stage is 17 feet.
- In 1991 and 1992, no serious flooding or flood damage occurred in the watershed.
12
PUBLIC UTILITY
SYSTEMS
6%
PUBLIC FACILITIES
0%
MISCELLANEOUS
2%
COMMERCIAL/IND.
7%
AGRICULTURAL
39%
WATER CONTROL
FACILITIES
10%
13
TRANSPORTATION
19%
PROTECTIVE
MEASURES
5%
RESIDENTIAL
13%
DEBRIS CLEARANCE
0%
Figure 6. Historical Flood Damage in the Maple Watershed.
PUBLIC FACILITIES
1%
MISCELLANEOUS
6%
AGRICULTURAL
22%
PUBLIC UTILITY
SYSTEMS
4%
14
RESIDENTIAL
17%
COMMERCIAL/IND.
41%
DEBRIS CLEARANCE
1%
WATER CONTROL
FACILITIES
5%
PROTECTIVE
MEASURES
4%
TRANSPORTATION
3%
Figure 7. Historical Flood Damage in the Wild Rice Watershed.
15
Figure 8. Residential Flood Damage by Township in the Wild Rice Watershed.
Flood Damage Downstream on the Main-Stem of the Red River
Damage outside the sub-watersheds (downstream on the main-stem of the Red River) are
assumed here to be associated only with Grand Forks, ND, and East Grand Forks, MN, (hereafter
referred to simply as 'Grand Forks'). Grand Forks is about 70 river miles (or 40 road miles)
downstream of the Maple and Wild Rice Watersheds. The USACE (1978) has estimated that
approximately 15% of river flow volume in the Red River at Grand Forks is associated with
drainage from the Maple Watershed (7%) and the WRW (8%). Communities further
downstream such as Pembina, ND, and Winnipeg, Manitoba, are considered influenced by many
other sub-watersheds and a variety of other hydrological systems within the RRV.
During the flood of 1997 (a 100-plus-year flood), Grand Forks received about $98
million in Federal assistance for residential and infrastructure flood damage (FEMA estimates
reported in Carlson, 1998). To approximate flood damage associated with each of the two
watersheds, this figure is multiplied by the percentage of Red River flow volume at Grand Forks
associated with each of the watersheds. Therefore, Grand Forks flood damage over a typical 10year period associated with water flows from the Maple Watershed are $6,860,000 and for the
WRW the figure is $7,840,000.
2.4. The Hydrologic Modeling of Wetland Storage and Flooding
Many of the assumptions in this present study to evaluate the feasibility of wetland
restoration and impoundment storage are based on previous studies of the relationships between
wetlands and flooding. Most of these studies were focussed in other areas of the country, in the
upper Midwest, and other parts the RRV. However, one study (a companion study to this
report) was conducted in the Maple and Wild Rice Watersheds.
Previous Studies on Wetland Storage and Flooding
Perhaps the most extensive written evaluation of flooding issues in the RRV is the report
by Miller and Frink (1984) for the United States Geological Society (USGS). This report notes
that due to its large size, geology, and climate, major flood events in the Red River are most
often associated with climatic conditions and, more specifically, with early spring snowmelt
especially after a wet fall. This is confirmed from the historical flood damage estimates within
the Maple and Wild Rice Watersheds (Tables 2 and 3).
Miller and Frink and others (McCombs-Knutson, 1984) note that because the Red River
basin is as wide as it is long and because the river flows northward, the timing of the flows on
the tributaries closely coincide with that on the main-stem adding to flood peaks.
16
Table 3. Effects of Wetland Storage in Reducing Peak Flows During Flood Events in the
Maple River at Enderlin, ND
High
Frequency
Flood Event
(2-10 Year)
Medium
Frequency
Flood Event
(25 Year)
Low
Frequency
Flood Event
(50 Year)
Very Low
Frequency
Flood Event
(100+ Year)
1) Peak CFS & Flood Stage
Baseline Situation
1,535
9.14
2,893
11.25
3,824
12.35
4,977
13.44
2) Peak CFS & Flood Stage
2,700 AF Wetland Storage
(1 AF Bounce)
Reduction in Flood Stage
1,357
8.79
2,706
11.00
3,630
12.14
4,737
13.23
3.8%
2.2%
1.7%
1.6%
3) Peak CFS & Flood Stage
5,400 AF Wetland Storage
(2 AF Bounce)
Reduction in Flood Stage
1,292
8.65
2,627
10.89
3,549
12.05
4,622
13.12
5.4%
3.2%
2.4%
2.4%
4) Peak CFS & Flood Stage
1,171
2,518
3,404
4,578
10,800 AF Wetland Storage
8.39
10.74
11.89
13.08
(4 AF Bounce)
Reduction in Flood Stage
8.5%
4.5%
3.7%
2.7%
* All wetland storage options assume that a maximum of 25% of the flow out of each sub-basin
is diverted into wetland storage.
Finally Miller and Frink summarize several previous studies that have attempted to
explain relationships between changing land use, drainage, and flooding in the RRV. In
summary, these studies have found that increased drainage does have an effect on small (highfrequency) flood events but a diminished or negligible effect on large-scale, low frequency (100
and 500 year) flood events. It is also noted that studies such as Moore and Larson (1980) have
concluded that statistical (regression) analyses of historical data involving changes in land use
and drainage and peak flows is problematic due to data that are limited both spatially and
temporally.
A study by the USACE in 1976 of the Charles River Watershed near Boston,
Massachusetts, found that wetland storage had a strong effect on peak flood events. However, it
should be noted that the climatic and hydrological conditions of this watershed differ greatly
from those of the RRV.
Other studies and commentary have noted that historical levels of drainage could have
made significant reductions in total flood levels in the Mississippi (Hey and Philippi, 1995) and
RRV Watersheds (Sierra Club, 1997). However, these analyses make the unrealistic assumption
17
that wetlands are empty at the time of flood events or that all potential wetland storage
contributes to reducing peak flood flows.
A more rigorous analysis of Mississippi River Watersheds found that restoring upland
wetlands could help reduce flood peaks by 1% to 23% with deep wetlands and from 5% to 9%
with shallow wetlands. They also noted that wetland restoration was most effective in reducing
flood damage during typical (25 year or less) storm events (USACE, 1994).
The hydrologic effects of wetland drainage were recently modeled with a hydrologic
simulation program model and detailed watershed level data in the Little Cobb River subwatershed of the LeSuer River Watershed in Minnesota (Miller, 1999). The study concluded that
wetlands drainage accounted for up to a 57% increase in annual peak discharge. However, the
study also concluded that potential decreases in flooding due to the addition of wetlands is
dependent on the quantity of available storage in wetlands prior to a flood event, and that
wetland storage had very little effect on reducing the magnitude of large (low frequency) flood
events.
Finally, a nonauthored and difficult to find hydrological analysis using empirical data for
three restored wetlands in the RRV concluded that:
“The restoration of small drained wetlands (1.8, 2.5, and 10.8 surface acres),
when done using a simple ditch plug and spillway, does not appear to provide any
flood control benefits. In fact, based on our sample, it appears more likely that
downstream flood control benefits will be reduced when compared to those,
which were provided by the drained wetland basin. The exception may be during
those flood events following a dry period when starting pond elevations are low”
(Red River Management Board, 1993).
Storage Volume of Wetlands
A critical factor in the role of wetlands in reducing peak flood flows is their storage
potential, or ‘bounce’ especially during major flood events. Bounce is a function of wetland
volume and depth as well as antecedent soil moisture conditions.
Hubbard (1982), in a survey of 213 small wetlands in northeastern South Dakota
immediately after the vernal thaw, determined that the wetlands on average were .67 acres in size
with an average maximum depth of 1.4 feet and an average volume of 0.73 acre feet (AF) of
water. It was also noted that much of the storage probably came from snowmelt and that excess
storage capacity existed meaning that the maximum volume of water that these wetlands can
store is a little less than an AF of water per surface acre of wetland.
A study in the Devils Lake area of North Dakota (Ludden, Frink, and Johnson, (1983),
found that wetlands on average store 0.6 AF per surface acre (AFPSA) during a 2-year flood
event, and 0.45 AFPSA during a 100-year flood event. From this data, one can deduce that
18
bounce, or available wetland storage during a major (100-year) flood event is about half an
AFPSA.
A study of three restored wetlands with simple plug ditches and earthen spill-ways in the
RRV found that the difference in storage between a 2-year and 100-year flood event ranged from
0.5 to 1.5 AFPSA of wetland (Red River Management Board, 1993).
As reported in Eppich, Apfelbaum, and Lewis (1998), the Minnesota DNR reports at least
1.5 AFPSA in Red River basin wetlands during wet periods (Terry and Adland, 1998), while the
DNR Division of Fish and Wildlife estimates wetland storage volume at 1 AFPSA. However, the
details regarding these studies is not provided, and it is not known whether their term of storage
volume refers to actual storage or available storage (bounce).
Finally, Epich, Apfelbaum, and Lewis (1998), a group of wetland restoration experts
recommend that wetlands constructed with drainage outlets not withdrawn (discharged) more
than 2 feet in order to maintain reasonably diverse and dense wetland vegetation.
Modeling Wetlands and Flooding in the Maple Watershed
Preliminary results of a hydrological modeling exercise quantifying relationships
between drained wetland storage and mainstream flood levels in the Maple Watershed (Bengtson
and Padmanabahn, 1999) is summarized below.
The Maple Watershed was subdivided into 48 sub-basins, and modeled using HEC-1, a
quasi-distributed lumped parameter hydrologic model that accounts for wetland storage, land
use, hydrologic conditions, and rainfall events. Wetland storage was modeled as diversions,
which permanently retained some of the outflow from each sub-basin. As water arrived at the
outlet of a sub-basin, 75% of the flow was routed downstream, while 25% was diverted until the
wetland storage was filled. After that, 100% of the flow would enter the stream. The 25%
diversion assumes that 25% of the overland flow in the watershed will be intercepted by
wetlands. Since the drained wetlands only comprise about 0.3% of the surface area of the
watershed, this is a generous assumption. Using the 25% diversion assured that all wetland
storage would be utilized.
The effect of changing the timing of the diversions was modeled by restricting their
outflow from each sub-basin after reaching 50% of the peak. This had the effect of reducing the
volume of runoff at a time nearer the peak flow and, thus, more effectively reducing the peak
flow. However, they considered it unlikely that all of the overland flow will somehow not be
intercepted by wetlands until the outflow reaches 50% of peak.
The assumption was that all NWI drained wetlands would be restored and their estimated
volume (on average 1 AFPSA of wetlands) is entirely available for flood storage. From this, it
was concluded that increased wetland storage gained by restoring drained wetlands in the Maple
Watershed did not materially affect peak flows at the watershed outlet for low-frequency flood
events, even when the storage available was increased four-fold. Changing the timing of the
19
diversions so that they would occur nearer the hydrograph peak only slightly decreased the peak
flow.
Table 3 summarizes reduction in peak flows and stages for 3 precipitation flood events
under a baseline condition (no wetland storage) and wetland storage of 2,700 AF (1 foot
bounce), 5,400 AF (2 foot bounce), and 10,800 AF (4 foot bounce). Reductions in peak flood
stages increased (albeit at a nonproportional and diminishing rate) as wetland bounce increased
and decreased as flood events became larger.
The study concluded that it is unlikely that storage in randomly located, uncontrolled
storage basins would “slice off the peak” of a flood hydrograph. For this to occur, each wetland
basin would need to remain empty until just the right time so that retained runoff does not
contribute to maximum peak flow. It is more likely that wetlands will begin to fill as snowmelt
and/or rainfall runoff begins to move overland and is intercepted by these wetlands. Thus, the
runoff potentially stored in available wetland basins would reduce the volume of runoff under the
rising limb of a flood hydrograph, which results in a slightly lower peak flow for low-frequency
flood events.
20
Chapter 3. The Feasibility of Wetland Restoration-Storage Programs
The economic feasibility of alternative wetland restoration options to reduce flood
damage in the Maple and Wild Rice Watersheds are evaluated in three ways. First, the costs of
wetland restoration will be compared to benefits (reduced flood damage) based on historical
flood damage in the watersheds and the results of hydrologic modeling exercises in the Maple
Watershed. Second, estimates will be made regarding minimum levels of flood stage and
damage reduction required for wetland restoration options to break even which do not rely on the
aforementioned hydrologic modeling results in the Maple Watershed. Finally, the per acre
annual values of additional (nonflood-related) wetland functions required for wetland restoration
options to break even are calculated.
In all three cases, feasibility estimates will be made over a hypothetical 20-year period in
the future and focus on flooding both within and outside the watersheds. The downstream focus
is, however, limited to the main-stem of the Red River at Grand Forks. Costs and benefits are
discounted to1999 dollars using a 5% discount rate.
The evaluation focuses on three wetland restoration options. First, simple flood storage
using wetland plugs with earthen spillways. Second, more complicated and expensive wetland
restoration which relies on drainage outlets that permit wetland volumes to be drawn down in
advance of flood events and, hence, increase available storage. And third, wetland restoration
intended to restore the full environmental services of wetlands using established restoration
criteria which is even more complicated and expensive as it involves making sure that soil, slope,
water, and vegetative characteristics of a restored wetland are very similar to natural wetlands in
a particular area.
3.1. Quantities and Locations of Previously Drained Wetlands
The location and size of previously drained wetlands in the upper sections of the
watersheds were identified though a GIS-based analysis of the NWI. It is possible that additional
wetlands, especially those drained many years ago, are not captured by the NWI. However,
these missing wetlands should not affect the feasibility estimates in this study because wetland
restoration costs and benefits are assumed to increase proportionately with wetland quantities.
Also, the restoration of many drained wetlands missing from the NWI is probably not
economically and/or politically feasible due to historical land use developments.
It should also be noted that for the option where wetland restoration is hypothesized to
take place on low cost lands in the upper sections of the watersheds, it is assumed that there are
actually more drained wetlands than in the NWI.
Previously drained wetlands and hydrology in the Maple and Wild Rice Watersheds are
illustrated in Figures 9 and 10 and summarized in Table 4. In the upper Maple Watershed there
are approximately 2,700 acres of drained wetlands. Their average size is 1.3 acres while the
most frequent (common) size is 0.5 acres, and wetland acreage is evenly split among small- (< 1
acre), medium- (1-5 acres), and large- (> 5 acres) size classes.
21
In the upper WRW there are approximately 12,600 acres of drained wetlands whose
mean size is 2.6 acres and the most frequent size is 2.5 acres.
The total costs of restoring wetlands include construction costs in the first year and
annual land rental payments throughout the life of the project, which in this present evaluation is
10 years. Operating and/or maintenance costs are uncertain and assumed to be either
insignificant and/or the responsibility of landowners renting their land.
Table 4. Wetland Acres by Size Classes in the Maple and Wild Rice Watersheds*
Upper Maple
Upper Wild Rice
Total
Acres
2,700
12,600
Small Wetland
Acres
(< 1 Acre)
700 acres
1,200acres
Medium
Wetland Acres
(1-5 Acres)
1,100
3,000
Large Wetland
Acres
(> 5 Acres)
900
8,400
3.2. The Costs of Wetland Restoration-Based Storage Programs
Construction Costs
The construction costs of restoring wetlands vary considerably depending on what type of
restoration is performed (plugging drains, establishing outlet flows, or restoring wetlands with
their full ecological services). These costs are also subject to economies of scale or, more
specifically, that per acre restoration costs decrease with the size of wetlands being restored.
Baseline construction costs used here are based on actual wetland restoration costs in northwest
Minnesota as well as the results of a large-scale wetland restoration/impoundment in the Alice
Lake area of North Dakota.
As reported in Sip (1998), the 1995 Minnesota Wetland Replacement/Mitigation Cost
Summary published by the Minnesota Board of Water and Soil Resources, estimates wetland
restoration costs to range from $95 to $ 30,000 per acre with an average of $3,000. In contrast,
the cost of impounding new wetlands ranges from $200 to $20,000 per acre with an average of
$1,500 per acre.
Eppich, Apfelbaum, and Lewis (1998) estimate that establishing a depressional wetland
control without land acquisition costs or an outlet control is approximately $1,500 per acre. The
cost of including an outlet control is $2,750 again excluding land acquisition costs. They also
estimate that the cost of constructing impounded wetlands (building dikes or berms) with outlet
controls is approximately $10,000 per acre excluding land acquisition costs. The authors also
note that many of these per acre wetland construction costs (especially permitting, design, and
engineering costs) can be reduced when large and/or many wetlands are being
restored/constructed.
22
Figure 9. Drained Wetlands and Hydrology, Maple Watershed.
23
24
Figure 10. Drained Wetlands and Hydology, Wild Rice Watershed.
An example of economies of scale in restoring wetlands is the Alice Lake Wetland in
North Dakota, where according to Renner (1999), dikes and outlet flow structures were
constructed in order to restore 3,500 wetland acres at a cost of approximately $930,000,
excluding land acquisition costs ($265 per acre).
Finally, Hammer et al., (1993) estimate that farmers should be able to construct an
effective wetland, including planting of limited vegetation, for a little less than $3,000 per acre.
For this present study, the construction costs of three types of wetland restoration will be
estimated: simple plugs and spillways, outlet control devices, and full ecological restoration.
Construction cost will be adjusted to account for economies of scale (small, medium, and large
wetlands) for each restoration option.
Simple wetland restoration/construction costs for plugging a wetland drain with an
earthen spillway are estimated to be $300 per acre for small-size wetlands (< 1 acre), $200 per
acre for medium-size wetlands (1-5 acres), and $100 per acre for large-size wetlands (> 5 acres).
Using wetland size classes for the two watersheds summarized in Table 3, total simple wetland
restoration/construction costs for the upper Maple Watershed are $520,000 and for the WRW the
cost is $1.8 million.
Restoring wetlands with outlet control is estimated to be twice as expensive ($600 per
acre for small-size wetlands, $400 per acre for medium-size wetlands, and $200 per acre for
large-size wetlands) resulting in construction costs in the Maple Watershed being $1,040,000 and
$3.6 million in the WRW.
Wetland restoration/construction costs providing full ecological services are estimated at
$3,000 per acre for small-size wetlands, $1,000 per acre for medium-size wetlands, and $500 per
acre for large-size wetlands. This results in total construction costs of $3.6 million in the Maple
Watershed and $10.8 million in the WRW.
Land Rental Values
Payments to farmers for the storage of water on their lands are considered to be the same
regardless of the wetland restoration option being evaluated. Annual per acre rental payments
are used because they require less up-front costs, it is not known how long the storage programs
will be required, and because reasonably accurate annual rental data exist for the watersheds
being studied. Finally, the land rental values reported here are considered low because due to
topological and ownership conditions it is likely that wetland restoration would require more
land than is actually restored. Alternatively, it is not likely that all procured land could be used
for wetland restoration
Land rental values in the upper Maple Watershed were obtained from county level
cropland rental values from 1993-1997 as reported by the North Dakota Agricultural Statistics
Service. A weighted average of cropland and pastureland rental rates was estimated. Also, to
account for lower quality land in the upper section of the watershed, land rental values were
adjusted on the basis of rental values of adjacent counties. Total rental value costs were
25
estimated by multiplying average county rental rates in the upper watershed ($40/acre) by the
number of drained wetlands in each county.
In the upper WRW, annual land values were estimated by making adjustments to assess
tillable land values reported by the Minnesota Department of Revenue. It was noted that in the
Maple Watershed annual rental values were 7% of total values, and this same percentage was,
therefore, used to convert capitalized land values to annual rental values in the WRW.
The map in Figure 11 shows the variation in township level rental values across the
township in the WRW and illustrates that variations in rental values are primarily a result of
geophysical characteristics. Specifically, rental values are highest in the lower watershed (the
lake plain) followed by middle (Beach Ridge) and upper (Glacial Moraine) parts of the
watershed.
Total land rental costs in the upper WRW were estimated by multiplying township rental
values by the number of drained wetland acres in each township and on average are $40 per acre
per year.
Rental costs on “cheap” lands in the upper sections of each of the two watersheds
involved the assumption that wetland restoration would occur only in townships or areas with
rental values below the average for the watershed. On average, these lands cost $35 per acre a
year to rent in the upper Maple Watershed and $26.50 per acre in the upper WRW. This requires
the assumption that there are more drained wetlands in the watershed than indicated by the NWI.
The total costs of restoring drained wetlands under different scenarios in the upper
sections of each of the two watersheds over 10 years are a summation of the present value of
construction costs in year 1 and land rental payments in years 1 through 20 (Table 5).
Wetland restoration costs over a 20-year period range from $1.8 million to $4.7 million in
the upper Maple Watershed and between $5.9 million and $12.8 million in the upper WRW. As
expected, the total costs of simple wetland restoration (plugging up a wetland) is cheaper than
restoring wetlands with outlets which is cheaper than restoration with full ecological services.
A more useful indicator of the relative cost of alternative restoration scenarios is the
annual storage cost per AF of water stored. Based on the literature previously described,
wetlands restored with a simple plug are expected to provide at most 1 AF of water storage per
surface acre of wetland during a major springtime flood event. In contrast, a wetland restored
with an outlet control device is expected to be able to hold up to 2 AFPSA (actually more storage
is possible but this would require seasonal drainage of wetlands that could possibly damage
wetland ecosystems).
26
27
Table 5. Wetland Restoration Costs in the Maple and Wild Rice Watersheds Over a 20-year Period
Total
Annual Rent 2
Construction
Costs (Year 1)
Total Costs
(20 Years) 3
Annual Cost per
Acre Foot Stored
Simple Restoration
Simple Restoration (Cheap Land)
$108,000
$94,500
$520,000
“
$1,841,157
$1,673,393
$34
$31
Restoration with Outlets
Restoration “
“
(Cheap Land)
$108,000
$94,500
$1 Million
“
$2,298,300
$2,130,536
$43
$39
Full Restoration
Full Restoration (Cheap Land)
$108,000
$94,500
$3.6 Million
“
$4,774,490
$4,606,250
$88
$85
Simple Restoration
Simple Restoration (Cheap Land)
$430,000
$334,000
$1.8 Million
“
$7,073,036
$5,876,664
$28
$23
Restoration with Outlets
Restoration “
“
(Cheap Land)
$430,000
$334,000
$3.6 Million
“
$8,787,322
$7,590,950
$35
$30
Upper Maple Watershed (2,700Acres)1
28
Upper Wild Rice Watershed (12,600 Acres)1
Full Restoration
$430,000
$9.1 Million
$14,025,417
Full Restoration (Cheap Land)
$334,000
“
$12,829,045
NOTES:
1. Wetland acreage based on the National Wetland Inventory.
2. Average annual rent in the upper Maple Watershed is $40 and $35 (cheap land) while in the Wild Rice
Watershed, land rents are $32 and $26 (cheap land).
3. Present values calculated using a 5% discount rate.
$56
$51
Finally, full wetland restoration efforts are also assumed to include outlet controls and
are, therefore, also expected to store 2 AFPSA of wetland. It can, therefore, be deduced that
wetland restoration in the upper Maple Watershed costs between $31 and $85 per AF of stored
water. The cheapest restoration-storage option appears to be the use of outlets. The same is true
for the upper WRW where restoration-storage costs range from $23 to $56 per AF of water
stored.
Wetland restoration-storage costs are cheaper in the upper WRW than in the upper Maple
Watershed because land values are lower and there are larger wetlands with cheaper per acre
restoration-construction costs.
3.3. The Potential Benefits of Wetland Restoration-Storage Options
To estimate the economic feasibility of alternative wetland restoration options, it is
necessary to calculate the potential benefits of storage as represented by reduced flood damage
both within and downstream of the Maple and Wild Rice Watersheds. This requires determining
how historical flood damage in the watersheds would have been reduced by alternative wetland
restoration options on the basis of hydrologic modeling exercises in the Maple Watershed and
then extrapolating this reduced damage into the future.
From 1989 to 1998, flood damage within the Maple Watershed was $29.3 million and
$102 million within the WRW. Flood damage outside the watersheds in Grand Forks that are
associated with water flows from the Maple Watershed is $6.9 million and $7.8 million for the
WRW (Chapter 2, Section 2.3).
The estimation of stage-damage curves that quantify the relationship between flood
levels and damage was not estimated for this study due to a lack of detailed elevation and sitespecific flood damage data. It is, therefore, assumed that annual reductions in peak flood stage
estimated for the Maple Watershed by Bengtson and Padmanabahn (1999) correspond directly
with reductions in flood damage. This assumption is probably more valid for agricultural-based
flood damage than residential flood damage, but without detailed stage-damage curves, no other
alternatives exist. This assumption will likely increase estimates of the benefits of wetlands for
reducing flooding because flood damage usually increases at an increasing rate with higher flood
stages. Finally, without any such hydrologic modeling completed for the WRW, it is necessary
to assume that the percentage relationships between wetland storage and flood stage levels are
the same for each watershed.
Potential reductions in flood damage in the two watersheds are based on estimated
reductions in peak flood stages of historical (1989-1998) flood events (high-, medium-, low-, and
very low-frequency floods), and alternative wetland storage (different levels of wetland acres
restored and alternative levels of storage bounce). Recall from Chapter 2 and Table 3
(hydrological modeling in the Maple Watershed), that wetland storage with 1 foot of bounce
reduces peak flood stage by 3.8% (high-frequency floods), 2.2% (medium-frequency floods),
1.7% (low-frequency floods) and 1.6% (very low-frequency floods). The corresponding
29
reductions in peak flood stage for 2 feet of storage bounce are 5.4%, 3.2%, 2,4%, and 2.4%
(Bengtson and Padmanabahn, 1999).
This reduced flood damage (1989-1998) is extrapolated to a hypothetical 20-year period
in the future by assuming that they will repeat themselves twice, and that the annual average of
this reduced flood damage occurs each year in the future. This future reduced flood damage is
then discounted using a 5% discount rate. Therefore, reduced 20-year flood damage in the
Maple Watershed with 1 foot of bounce and 2,700 AF of storage is $800,800 and $1,170,000
with 2 feet of bounce (5,400 AF of storage). The corresponding values for the WRW (albeit
based on hydrologic modeling results from the Maple Watershed) are $2.4 million with 1 foot of
bounce and 12,600 AF storage, and $3.6 million for 2 feet of bounce and 25,200 AF storage
(Tables 6 and 7). These values are considered project benefits over a 20-year period.
3.4. Net Present Values and Benefit-Cost Ratios of Wetland Restoration Options
All of the wetland storage options evaluated have costs that greatly exceed their benefits.
Net present values are all negative and benefit-cost ratios range from 1:1.4 to 1:4.1 in the Maple
Watershed and 1:1.6 to 1:3.9 in the WRW (Table 8). Even with the optimistic scenario with
restoration on the cheapest lands and 2 feet of bounce, economic feasibility defined as benefits
greater than costs, is not achieved.
Alternatively, wetland restoration storage options would have to reduce peak annual
flood stage and total historical flood damage by between 3.4% and 9.6% in the Maple Watershed
and by 4.3% to 10.2% in the WRW before breaking even (Table 9). These estimates of required
reductions in peak flood stage and flood damage required for economic feasibility may be useful
to future and/or alternative hydrologic modeling studies of the effects of wetland storage on
flooding.
3.5. Wetland Restoration Feasibility Considering Additional Benefits of Wetlands
Wetland restoration for the purpose of flood control in two typical sub-watersheds of the
RRV has been demonstrated as nonfeasible from an economic standpoint. However, some
people would argue that these restored wetlands would likely provide additional (nonfloodrelated) benefits such as services to animal and plant species, improving water quality, and
recreational and aesthetic services.
To evaluate if the inclusion of nonflood-related wetland benefits would make wetland
restoration-storage activities economically feasible, the minimum required values of these
‘additional’ wetland benefits in order for restoration-storage alternatives to break even were
estimated. These minimum required wetland values were then compared to available estimates
of wetland benefits found in the literature.
30
Table 6. Historical and 20-Year Expected Reductions in Flood Damage Due to Wetland Storage in the Maple Watershed
NPV
(20 Years)
31
1989
1992
1993
1994
1995
1996
1997*
1998
Total Damage
($ millions)
0.3
0.1
12.4
0.5
0.9
1.8
19.4
0.8
Peak CFS
981
710
3,770
3,040
1,830
3,860
4,060
1,730
8.4
7.3
12.7
11.5
10.1
12.3
9.9
High
High
Low
Medium
High
Low
12.6
Very
Low
High
$11,400
$3,800
$210,800
$11,000
$34,200
$30,600
$310,400
$30,400
$800,800
$16,200
$5,400
$297,600
$16,000
$48,600
$43,200
$465,600
$43,200
$1,170,000
Peak Flood Stage (ft)
Type of Flood Event
(Frequency)
Reduced Flood Damage with
Simple Restoration
(1 ft bounce, 2,700 AF
storage)
Reduced Flood Damage with
Restoration using Outlets
(2 ft bounce, 5,400 AF
storage)
Notes:
- Flood stage at Enderlin, ND, is 9 feet.
- No major flood damage recorded in 1990 or 1991.
- Hydrological relationships from a study in the Maple Watershed (Bengtson and Padmanabahn, 1999).
- From Table 3, storage with 1 foot of bounce reduces peak flood stage by 3.8% (high-frequency floods), 2.2% (medium-frequency floods), 1.7%
(low- frequency floods), and 1.6 (very low-frequency floods). The corresponding reductions for storage with 2 feet of bounce are 5.4%, 3.2%,
2.4%, and 2.4%.
- Historical flood damage based on estimates by Kjelland (1999) and expanded 20 years into the future using a 5% discount rate.
- Assumption of direct (linear) relationship reductions in flood stage (ft) and flood damage ($).
- *1997 Flood damage includes Grand Forks damage associated with flows from the watershed.
Table 7. Historical and 20-Year Expected Reductions in Flood Damage Due to Wetland Storage in the Wild Rice Watershed
(Based on hydrological modeling in the Maple Watershed)
NPV
(20 years)
32
1989
1990
1993
1994
1995
1996
1997*
1998
Total Damage
($ millions)
$2.6
$0.6
$15
$2.1
$0.9
$3.3
$76.6
$8.7
Peak CFS & Stage (ft)
5,480
1,100
3,680
2,600
3,200
5,750
10,600
6,550
29.6
14.3
27.2
21.2
25.3
28.7
33.9
26.9
Low
High
Medium
High
High
Low
Very Low
Low
$44,200
$22,800
$330,000
$79,800
$34,200
$56,100
$1,225,000
$147,900
$2.4
(million)
$62,400
$32,400
$480,000
$113,400
$48,600
79,200
$1,838.000
$208,800
$3.6
(million)
Peak Flood Stage (ft)
Type of Flood Event
(Frequency)
Reduced Flood Damage with
Simple Restoration
(1 ft bounce, 2,700 AF
storage)
Reduced Flood Damage with
Restoration using Outlets
(2 ft bounce, 5,400 AF
storage)
Notes:
- Flood stage at Hendrum, MN, is 17 feet.
- No flooding in 1991 and 1992.
- Hydrological relationships from a study in the Maple Watershed (Bengtson and Padmanabahn, 1999).
- From Table 3, storage with 1 foot of bounce reduces peak flood stage by 3.8% (high-frequency floods), 2.2% (medium-frequency floods), 1.7%
(low-frequency floods), and 1.6 (very low-frequency floods). The corresponding reductions for storage with 2 feet of bounce are 5.4%, 3.2%,
2.4%, and 2.4%.
- Historical flood damage based on estimates by Kjelland (1999) and expanded 20 years into the future using a 5% discount rate.
- Assumption of direct (linear) relationship reductions in flood stage (ft) and flood damage ($).
- *1997 Flood damage includes Grand Forks damage associated with flows from the watershed.
Table 8. Benefit-Cost Ratios of Alternative Wetland Restoration-Storage Options in the
Maple and Wild Rice Watersheds
Total Costs
(20 Years)
Reduced
Flood
Damage
(20 years)
BenefitCost
Ratio
$1.8 million
$800,800
1:2.3
$1.6 million
$800,800
1:2.1
$2.3 million
$1,170,000
1:2
$2.1 million
$1,170,000
1:1.8
$4.7 million
$1,170,000
1:4.1
$4.6 million
$1,170,000
1:3.9
$1.7 million
$1,170,000
1:1.4
$7 million
$2.4 million
1:2.9
$5.9 million
$2.4 million
1:2.4
$8.8 million
$3.6 million
1:2.5
$7.6 million
$3.6 million
1:2.1
$14 million
$3.6 million
1:3.9
$12.9 million
$3.6 million
1:3.6
$5.9 million
$3.6 million
1:1.6
Upper Maple Watershed
(2,700 Acres of Upper Wetlands Restored)1
Simple Restoration
(1 ft bounce, 2,700 AF storage)
Simple Restoration on Cheapest Land
(1 ft bounce, 2,700 AF storage)
Restoration with Outlets
(2 ft bounce, 5,400 AF Storage)
Restoration “
“
on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Full Restoration
(2 ft bounce, 5,400 AF Storage)
Full Restoration on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Most Optimistic Scenario:
(Simple Restoration on Cheapest Land,
2 feet of bounce, and 5,400 AF Storage)
Upper Wild Rice Watershed
(12,600 Acres of Upper Wetlands Restored )
Simple Restoration
(1 ft bounce, 12,600 AF storage)
Simple Restoration on Cheapest Land
(1 ft bounce, 12,600 AF storage)
Restoration with Outlets
(2 ft bounce, 12,600 AF Storage)
Restoration “
“
on Cheapest Land
(2 ft bounce, 12,600 AF Storage)
Full Restoration
(2 ft bounce, 12,600 AF Storage)
Full Restoration on Cheapest Land
(2 ft bounce, 12,600 AF Storage)
Most Optimistic Scenario:
(Simple Restoration on Cheapest Land,
2 feet of bounce, and 12,600 AF Storage)
Notes:
1. Wild Rice Watershed benefit estimates are based in part on hydrologic modeling results conducted in
the Maple Watershed.
2. Nonflood-related benefits of wetlands are not considered here.
33
Table 9. Required Reductions in Peak Flood Stage and Flood Damage for Alternative
Wetland Restoration-Storage Options to Break Even
Total
Flood
Damage
(20 years)
Required Reduction
in Flood Damage
(Peak Flood Stage)1
to ‘Break Even’
$1.8
million
$1.6
million
$2.3
million
$2.1
million
$4.7
million
$4.6
million
$1.6
million
$36.5
Million
“
3.7%
“
4.6%
“
4.3%
“
9.6%
“
9.2%
$7
million
$5.9
million
$8.8
million
$7.6
million
$14
million
$12.9
million
$5.9
million
$121.6
Million
“
5.2%
“
6.4%
“
5.5%
“
10.2%
“
9.4%
Total
Costs
(20 years)
Upper Maple Watershed
(2,700 Acres of Upper Wetlands Restored )1
Simple Restoration
(1 ft bounce, 2,700 AF storage)
Simple Restoration on Cheapest Land
(1 ft bounce, 2,700 AF storage)
Restoration with Outlets
(2 ft bounce, 5,400 AF Storage)
Restoration “
“
on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Full Restoration
(2 ft bounce, 5,400 AF Storage)
Full Restoration on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Most Optimistic Scenario:
(Simple Restoration on Cheapest Land,
2 ft of bounce, and 5,400 AF Storage)
Upper Wild Rice Watershed
(12,600 Acres of Upper Wetlands Restored )
Simple Restoration
(1 ft bounce, 2,700 AF storage)
Simple Restoration on Cheapest Land
(1 ft bounce, 2,700 AF storage)
Restoration with Outlets
(2 ft bounce, 5,400 AF Storage)
Restoration “
“
on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Full Restoration
(2 ft bounce, 5,400 AF Storage)
Full Restoration on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Most Optimistic Scenario:
(Simple Restoration on Cheapest Land,
2 ft of bounce, and 12,600 AF Storage)
Notes:
3.4%
3.4%
4.3%
4.3%
1. Reductions in peak flood stage are assumed to be directly related to reduced flood damage.
2. Nonflood-related benefits of wetlands are not considered here.
34
The value of nonflood-related wetland benefits (on an annual per acre level) required for
alternative wetland restoration-storage options to break even, range from $9 to $67 in the Maple
Watershed and from $21 to $97 in the WRW (Table 10). The higher end values ($67 and $97)
are associated with the ‘full’ wetland restoration options, which are the most likely restoration
alternatives that will provide a full range of wetland functions.
In the upper Great Plains a limited amount of wetland valuation research has been
conducted (Hubbard, 1989; Leitch and Hovde, 1996; and Roberts and Leitch, 1997). The results
of these studies indicate that combined user, owner, and societal values of selected wetlands in
the region (including flood control values) range from $50 to $326 per acre per year with an
average value of $140 (Leitch and Hovde, 1996). From this present study, gross annual floodrelated benefits of wetlands (gross flood reduction benefits divided by 20 years and the acres of
restored wetlands) range from $15 to $22 per acre in the Maple Watershed and $11 to $24 per
acre in the WRW.
This would seem to imply that if the nonflood-related benefits of wetlands are
considered, some of the cheaper wetland restoration options to reduce flood damage could be
economically feasible. However, this is a premature conclusion for three reasons. First, existing
estimates of the nonflood-related benefits of wetlands have focussed on only a few individual
wetland locations, and there is no guarantee that all of the wetlands in the Maple or WRWs have
similar characteristics. Second, if large numbers of wetlands were restored in these watersheds,
then the per acre value of wetland benefits would likely decline significantly due to the law of
diminishing marginal returns (there is a finite number of wetland acres that birds or
recreationists can utilize).
Finally, many of the nonflood-related wetland benefits are comprised of consumer
surplus values (not necessarily associated with actual money) making the provision of this public
good difficult to finance. It may be that only full wetland restoration will provide substantial
wetland function values, which is still infeasible due to their high costs.
In summary, it is unlikely that the inclusion of nonflood-related wetland benefits would
make wetland restoration-storage projects in the RRV economically feasible. However, more
research is needed regarding the valuation of wetland benefits. Of particular interest is how per
acre wetland values change when large numbers of wetlands are restored, and whether it is valid
to transfer wetland benefit estimates across time and space. Additional research is also needed to
compare nonflood-related wetland function values among different types of restored wetlands
(i.e., simple restoration, wetlands with outlets, and full restoration).
35
Table 10. Required Values of Other (Nonflood-Related) Wetland Benefits in Order for
Wetland Restoration with Full Environmental Services to be Feasible
Net Benefits of
Wetland
Required Annual Per Acre
Restoration for Value of ‘Other’ Wetland
Flood Control Benefits for Restoration to
(20 Years)
Break Even
Upper Maple Watershed
(2,700 Acres of Upper Wetlands Restored )1
Simple Restoration
(1 ft bounce, 2,700 AF storage)
Simple Restoration on Cheapest Land
(1 ft bounce, 2,700 AF storage)
Restoration with Outlets
(2 ft bounce, 5,400 AF Storage)
Restoration “
“
on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Full Restoration
(2 ft bounce, 5,400 AF Storage)
Full Restoration on Cheapest Land
(2 ft bounce, 5,400 AF Storage)
Most Optimistic Scenario:
(Simple Restoration on Cheapest Land,
2 ft of bounce, and 5,400 AF Storage)
- $1 million
$19
- $ 873,000
$16
- $1.1 million
$21
- $960,000
$18
-$3.6 million
$67
- $3.4 million
$64
- $1 million
$9
- $5.9 million
$43
- $4.6 million
$32
- $6.2 million
$48
- $5 million
$37
- $11.4 million
$97
- $ 10.2 million
$86
- $3.3 million
$21
Upper Wild Rice Watershed
(12,600 Acres of Upper Wetlands Restored )
Simple Restoration
(1 ft bounce, 12,600AF storage)
Simple Restoration on Cheapest Land
(1 ft bounce, 12,600 AF storage)
Restoration with Outlets
(2 ft bounce, 25,200 AF Storage)
Restoration “
“
on Cheapest Land
(2 ft bounce, 25,200 AF Storage)
Full Restoration
(2 ft bounce, 25,200 AF Storage)
Full Restoration on Cheapest Land
(2 ft bounce, 25,200 AF Storage)
Most Optimistic Scenario:
(Simple Restoration on Cheapest Land,
2 ft of bounce, and 25,200 AF Storage)
36
Chapter 4. The Feasibility of Impoundment-Storage Programs
The use of impoundments to store water in low-lying agricultural fields with outlet
control devices is closely related to and often confused with wetland restoration activities. In
this chapter, impoundments for flood control will be explained and their economic feasibility in
reducing flood damage will be evaluated.
4.1. An Introduction to Impoundments for Flood Control
Impoundments utilizing outlet control devices can store more water than restored
wetlands (usually about 4 AF of water per acre of impoundment versus the 1 to 2 AF assumed
for restored wetlands) primarily because they are designed and managed solely for the purpose of
flood control. Impoundments are most likely to be constructed in low-lying areas and their size
is expected to be relatively large in order to take advantage of economies of scale. When used in
an area of seasonal flooding such as the RRV, their water levels would likely be drawn down
significantly well in advance of flood events.
Impoundments for flood control purposes have been used for several years in the Devils
Lake region of North Dakota and are currently being proposed for use in the WRW in
Minnesota.
In North Dakota, the state government through the Available Storage Acreage Program
(ASAP) has, since 1996, paid upland farmers to store water on their fields in order to prevent
additional flooding in the Devils Lake basin. ASAP stored approximately 8,000 AF of water in
1996, 22,000 in 1997, and 21,000 in 1998. This storage has had the effect of reducing inflows
into Devils Lake by approximately 40,000-50,000 AF and kept the lake from rising about four to
five inches (NDSWC, 1998, 1999). The average size of an impoundment was 87 acres, with a
range in size from 2 to 858 acres.
The ASAP program pays farmers up to $50 per acre annually to store water, which is
higher than published rental rates in the region (and the rental rates used to evaluate the
feasibility of wetland restoration in the Maple and Wild Rice Watersheds). This price premium
is likely a result of the uncertainty associated with the longer term effects of water storage on
farmland ecology and because farmers are responsible for much of the required impoundment
construction and maintenance activities. In fact, as noted from ASAP accounting documents,
most impoundment sites incurred zero or minimal ($4 to $15 per acre) structural construction
costs. More information concerning the details of the ASAP program is contained in Appendix
B.
In Minnesota, the Wild Rice Watershed Management Board (WRWMB) is currently
developing a pilot project utilizing natural water storage areas in the upper watershed to reduce
local and watershed flood damage. They are currently identifying natural water detention sites
that are linked to downstream flood damage and where only minor structural changes and
improvements are required to impound water.
37
As the project has just recently been proposed, no specific impoundment cost data have
been obtained. However, according to Houston Engineering (1999), a break-even cost estimate
of $1,000/AF has been made. Also, the project intends to purchase land from farmers based on
tax assessment values of agricultural land while criteria for the design and construction of the
water storage sites will be based on the ‘Minnesota Wetland Restoration Guide’ (1992). More
information about this proposed impoundment-storage project is also contained in the Appendix
B
4.2. The Feasibility of Impoundment Storage in the Maple and Wild Rice Watersheds
To evaluate the economic feasibility of using impoundments to reduce flooding in the
Maple and Wild Rice sub-watersheds of the RRV, the following assumptions will need to be
made.
First, the land area available for impoundments is assumed to be equal to the amount of
potential wetland restoration analyzed in the Maple and Wild Rice Watersheds (2,700 acres and
12,600 acres, respectively). This allows direct comparisons with the feasibility of impoundments
and wetland restoration options. It also permits the utilization of existing hydrological modeling
results in the Maple Watershed (Bengtson and Padmanabahn, 1999). In reality, a great deal of
additional land is likely to be available for impoundments in each of the watersheds. However,
our focus here is on the relative economic efficiency of impoundments in reducing flood damage
(i.e., a benefit-cost ratio), and it is assumed that an increase in the number of impoundment acres
would be associated with a proportional increase in costs and benefits.
Second, based on the experiences of the Devils Lake and Wild Rice impoundment
programs, impoundments in this analysis are assumed to have a storage capacity (bounce) of 4
feet per surface acre. And, this storage is assumed to reduce peak flood stage as in the same way
as wetland storage (Table 3).
Third, based on a summary of construction costs by Eppich, Apfelbaum, and Lewis
(1998) and previous estimates of the costs of restoring large wetlands with outlet control devices,
the cost of such impoundments are assumed to be $200 per acre plus land rental costs
Finally, land rental costs are the same as used in renting cropland for wetland restoration
and are based on reported rental rates by the National Agricultural Statistics Service (NASS) in
the Maple Watershed and by county assessors in the WRW. Evaluations of impoundments are
made using average rental values and lower cost (cheaper) land rentals.
The total cost of impounding 2,700 acres in the Maple Watershed over 20 years is $1.8
million or $1.7 million using lower priced land (Table 11). With storage of 10,800 AF of
water annually, the annual per acre foot cost of storing water is $9 on regular priced land and $8
on cheaper land. In the WRW, the total cost of impounding 12,600 acres over 20 years is $7.4
million and $6.5 million, if only lower priced land is utilized. Because such impoundments
would store 50,400 AF of water annually, the annual cost per AF stored is $7 (regular land
prices) and $6 (on cheaper land).
38
Table 11. Cost of Impoundment-Storage in the Maple and Wild Rice Watersheds
Annual Rent 2
Construction
Costs
(Year 1)
Total Costs
(20 Years) 3
Annual Cost
per Acre Foot
Stored
$108,000
$95,00
$1.3 million
“
$1.8 million
$1.7 million
$9
$8
$403,000
$334,000
$6 million
“
$7.4 million
$6.5 million
$7
$6
Upper Maple Watershed (2,700Acres)1
Impoundments using Average Land Prices
Impoundments using Cheapest Land Prices
39
Upper Wild Rice Watershed (12,600 Acres)1
Impoundments using Average Land Prices
Impoundments using Cheapest Land Prices
NOTES:
1. Impoundment acreages are hypothetical and expected to be potentially much higher and each acre of impoundment is expected to
store 4 AF of water.
2. Average annual rent in the upper Maple Watershed is $40 and $35 (cheap land) while in the Wild Rice
Watershed, land rents are $32 and $26 (cheap land).
3. Present values calculated using a 5% discount rate.
Again, this reduced flood damage is extrapolated to a hypothetical 20-year period in the
future by assuming that they will repeat themselves twice and that annual average values occur
each year in the future. Therefore, reduced 20-year flood damage associated with impoundment
storage is $1.6 million in the Maple Watershed and $4.5 million in the WRW (Tables 12 and 13).
Therefore, the benefit-cost ratio for using impoundment to reduce flood damage in the
Maple Watershed is 1:1.2 for regular priced land and 1:1.1 for cheap land, while in the WRW the
benefit-cost ratios are 1:1.7 and 1:1.5 (cheap land).
These benefit-cost ratios of impoundments indicated that costs are approximately equal to
benefits. It is likely, therefore, that impoundments for flood control have the potential to be
feasible. Such feasibility is likely to occur when land can be rented or purchased at prices
markedly lower than watershed averages, when construction costs are lower than $200 per acre,
and when there are direct hydrological relationships between impoundments and downstream
flooding. The inclusion of additional (nonflood-related) wetland benefits are not included here
because it is unlikely that any will be provided by impoundments which are subject to seasonal
drainage.
Finally, it is interesting to note that two cases of actual impoundment-storage programs
being undertaken in the RRV (the Devils Lake ASAP Program and in the proposed WRW
impoundment demonstration program), closely mirror the above scenarios for impoundmentstorage feasibility (impoundments on low cost lands and which are limited in scale and are sitespecific).
40
Table 12. Historical and 20-Year Expected Reductions in Flood Damage Due to Impoundment-Storage in the Maple
Watershed
Total Damage
($ millions)
Peak CFS & Stages (ft)
41
Type of Flood Event
(Frequency)
Reduced Flood Damage with
2,700 Acres of Impoundments
(4 ft bounce, 10,800 AF
storage)
Notes:
1989
1992
1993
1994
1995
1996
1997*
1998
$0.3
981
8.4 ft
$0.1
710
7.3 ft
$12.4
3,770
12.7 ft
$0.5
3,040
11.5 ft
$0.9
1,830
10.1 ft
$1.8
3,860
12.3 ft
$0.8
1,730
9.9 ft
High
High
Low
Medium
High
Low
$19.4
4,060
12.6 ft
Very
Low
$25,500
$8,500
$458,800
$22,500
$76,500
$66,600
$523,800
$68,000
NPV
(20Years)
High
$1.6 million
- Flood stage at Enderlin, ND, is 9 feet.
- No major flood damage recorded in 1990 or 1991.
- Hydrological relationships from a study in the Maple Watershed (Bengtson and Padmanabahn, 1999).
- From Table 3, Storage with 4 feet of bounce reduces peak flood stage by 8.5% (high-frequency floods), 4.5% (medium-frequency floods),
3.7% (low-frequency floods),and 2.7% (very low-frequency floods).
- Historical flood damage based on estimates by Kjelland (1999).
- Assumption of direct (linear) relationship reductions in flood stage (ft) and flood damage ($).
- *1997 Flood damage includes Grand Forks damage associated with flows from the watershed.
Table 13. Historical and 20-Year Expected Reductions in Flood Damage Due to Impoundment-Storage in the Wild Rice
Watershed (Based on hydrological modeling in the Maple Watershed)
42
1989
1990
1993
1994
1995
1996
1997*
1998
Total Damage
($ millions)
$2.6
$0.6
$15
$2.1
$0.9
$3.3
$76.6
$8.7
Peak CFS & Stages
5,480
1,100
3,680
2,600
3,200
5,750
10,600
6,550
Low
High
Medium
High
High
Low
Very Low
Low
$96,200
$51,000
$675,000
$178,500
$76,500
$122,100
$2,068,200
$321,900
Type of Flood Event
(Frequency)
Reduced Flood Damage with
12, 600 acres of
Impoundments
(1 ft bounce 50,400 AF
storage)
Notes:
- Flood stage at Hendrum, MN, is 17 feet.
- No flooding in 1991 and 1992.
- Hydrological relationships from a study in the Maple Watershed (Bengtson and Padmanabahn, 1999).
- From Table 3, Storage with 4 feet of bounce reduces peak flood stage by 8.5% (high-frequency floods), 4.5% (medium-frequency floods),
3.7% (low-frequency floods),and 2.7% (very low-frequency floods).
- Historical flood damage based on estimates by Kjelland (1999).
- Assumption of direct (linear) relationship reductions in flood stage (ft) and flood damage ($).
- *1997 Flood damage includes Grand Forks damage associated with flows from the watershed.
NPV
(20
Years)
$ 4.5
million
Chapter 5. Summary and Conclusions
This study evaluated the economic feasibility of restoring wetlands and constructing
impoundments in order to reduce flood damage in two sub-watersheds of the RRV. The benefits
and costs of the following storage options were evaluated: simple wetland restoration, wetland
restoration with outlet control devices to increase storage capacity, wetland restoration with the
provision of full environmental services, and finally, the construction of impoundments with
outlet flow structures.
Construction costs were estimated from wetland restoration guidelines and the
experiences of previous water storage projects in the region. Land rental values were based on
rental value surveys in North Dakota and county tax assessments in Minnesota.
The expected benefits of storage programs were based on expected reductions in
historical (1989-1998) flood damage both within and downstream of the watersheds extrapolated
over a hypothetical 20-year period in the future. Specifically, reduced peak flood stage
associated with alternative levels of wetland restoration- and impoundment-based storage
options, were based on hydrological modeling estimates in the Maple Watershed by Bengtson
and Padmanabahn (1999). With the absence of stage-damage curves, it was assumed that
reduced peak flood stage reduced monetary flood damage proportionally. Reduced flood
damage was extrapolated and discounted for a hypothetical 20-year period in the future meaning
that the historical wet cycle of the last 10-year cycle (which included a ‘100-year’ flood) was
assumed to continue in the future.
This study utilized site-specific biophysical and socioeconomic data and a variety of
assumptions that were justified by previous studies and the existing literature. Most of the
assumptions used were either beneficial or neutral to the cause of using wetland restoration to
reduce flood damage. These include the assumptions that the recent wet cycle (1989-1998) will
continue for the next 20 years, and that reductions in peak flood stage was assumed to reduce
historical flood damage proportionately. These assumptions, which increase the potential
benefits of wetland and impoundment programs, strengthen or provide additional confidence in
the major conclusion this study: that large-scale wetland restoration programs are not an
economically feasible way to reduce flood damage in the RRV.
None of the wetland restoration options evaluated were economically feasible. Benefitcost ratios ranged from 1:1.4 for the most optimistic scenario (simple, low cost, and high
storage), to 1:4.1 for more complex restoration (intended to provide a full range of wetlandbased goods and services). Similarly, wetland restoration options would need to reduce peak
flood stage and related damage by between 3.4% to 10% to break even. The inclusion of
additional (nonflood-related) wetland benefits did not make wetland restoration economically
feasible. More research on this topic is warranted, especially with regard to the creation of
nonflood-related wetland benefits when large numbers of wetlands are restored across entire
watersheds and/or regions.
Finally, the use of impoundments to store water and reduce flood damage was evaluated.
Impoundments can store more water than wetlands but they are not likely to provide many
43
additional goods and services. Impoundments were found to be more cost effective in reducing
flood damage than wetlands, but with benefit-cost ratios ranging from 1:1.1 to 1:1.7, they also
were not considered economically feasible.
In conclusion, neither wetland restoration alternatives, nor the construction of
impoundments are considered economically feasible methods to store water and reduce flood
damage in the RRV.
However, it is possible (although not evaluated fully in this present study) that such
storage options could be feasible if implemented on a site-specific basis. This would likely
involve cases when storage sites can be procured at below average rental rates in locations with
direct hydrological impacts on downstream flooding, especially when they provide significant
levels of additional (nonflood-related) goods and services. For this reason, more research is
warranted regarding strategies to improve both the valuation of the goods and services provided
by wetlands and the site-specific modeling of the interactions between wetland storage and
flooding.
44
References
Bengtson, M., and G. Padmanabahn. 1999. A Hydrological Model for Assessing the Influence of
Wetlands on Flood Hydrographs in the Red River Basin. Report Submitted to the
International Joint Commission. Civil Engineering Department at North Dakota State
University, Fargo.
Carlson, G. 1999. The Economic Effects of the 1997 Flood on the Red River Valley. Master’s
Thesis, University of North Dakota, Department of Geography, Grand Forks.
Eppich, D., S. Apfelbaum, and L. Lewis. 1998. “Small Wetlands Use for Stormwater Runoff
Management in the Red River of the North Basin.” In: Compendium of Technical and
Scientific Advisory Committee Working Papers. Report Prepared in Support of the Red
River Basin Damage Reduction Workgroup.
Hammer, D. A., B. P. Pullin, T. A. McCaskey, J. Eason, and V.W. Payne. 1993. “Treating
livestock wastewater with constructed wetlands.” In Constructed wetlands for water
quality improvement. Edited by Gerald Moshiri, Boca Raton, Fl. Lewis Publishers, Inc.
Hey, D., and N. Philippi. 1995. “Commentary on Flood Reduction Through Wetland
Restoration: The Upper Mississippi River Basin as a Case History.’” Restoration
Ecology 3(1), 1995.
Houston Engineering, Inc. 1999. Personal Communications. Fargo, North Dakota.
Houston Engineering, Inc. 1999. Flood Storage Easements Pilot Program Proposal. Fargo,
North Dakota.
Hubbard, D. 1982. “Surface Area-Volume Relationships of Wetland Basins in the Interior of
the Coteau Des Prairies.” Proceedings of the South Dakota Academy of Science Vol. 61.
Hubbard, D. 1989. “Wetland values in the prairie pothole region of Minnesota and the
Dakota’s. Biological Report 88(43). Brookings, SD: U.S. Fish and Wildlife Service,
Cooperative Research Service.
IJC. 1997. Interim Report of the International Joint Commission Red River Basin Task Force.
Red River Flooding, Short-Term Measures. December 1997.
IJC-NDSU. 1999. The Collection of GIS-Based Data in the Maple (ND) and Wild Rice (MN)
Sub-Watersheds of the Red River Valley. Report compiled by the Agricultural
Economics Department, North Dakota State University for the Red River Basin
Taskforce of the International Joint Commission. Fargo, North Dakota.
International Coalition for Land/Water Stewardship in the Red River Basin. 1989. Land and
Water Guide. Moorhead, Minnesota.
45
Kjelland, M. 1999. Unpublished Master’s Thesis. Department of Agriculture Economics.
North Dakota State University, Fargo.
Krenz, G., and J. A. Leitch. 1993. A River Runs North: Managing an International River. Red
River Water Resources Council. Fargo, North Dakota.
Leitch, J. A., and B. Hovde. 1996. “Empirical valuation of prairie potholes: Five case studies.”
Great Plains Research 6:25-39.
Ludden, A, D., Frink, and D. Johnson. 1983. “Water Storage Capacity of Natural Wetland
Depressions in the Devils Lake Basin of North Dakota” Journal of Soil and Water
Conservation 38(1):45-48.
McCombs-Knutson. 1984. Water Resources Engineering/Planning Program for the Red River
of the North Basin in Minnesota. Prepared by McCombs-Knutson Associates, Inc. for
the Lower Red River Watershed Management Board (LRRWMB), May 1984.
Meyer, A. J. 1998. Estimating the Effect Wetlands Have on Flood Hydrographs, Through
Computer Simulation. Master’s Thesis, Department of Agricultural Economics, North
Dakota State University, Fargo.
Miller, R. 1999. Hydrologic Effects of Wetland Drainage and Land Use Change in a Tributary
Watershed of the Minnesota River Basin: A Modeling Approach. Master’s Thesis,
University of Minnesota, St. Paul.
Miller, J. E., and D. L. Frink. 1984. Changes in Flood response of the Red River of the North
Basin, North Dakota-Minnesota. Water-Supply Paper 2243, U.S. Geological Survey,
Alexandria, Virginia.
Minnesota Board of Water and Soil Resources. 1992. Minnesota Wetland Restoration Guide.
St. Paul, Minnesota.
Moore, I, and C. Larson. 1980. “Hydrologic impact of draining small depressional watersheds.” Journal of Irrigation and Drainage. Proceedings of the ASCE, 106(IR4):345363.
North Dakota State Water Commission. 1996. UPDATE: Governor’s Emergency Plan for
Devils Lake. Bismarck.
North Dakota State Water Commission. 1997. UPDATE: Governor’s Emergency Plan for
Devils Lake. Bismarck.
North Dakota State Water Commission. 1998. UPDATE: Governor’s Emergency Plan for
Devils Lake. Bismarck.
46
North Dakota State Water Commission. 1999. UPDATE: Governor’s Emergency Plan for
Devils Lake. Bismarck.
Red River Management Board. 1993. Hydrologic Analysis of Restored Wetlands. Internal
Report (author unknown), December, 17, 1993.
Renner, R. 1999. “Wetland Projects Help Reduce Flooding in North Dakota.” Waterfowl 2000,
12(1) page 7.
Roberts, L. A., and J. Leitch. 1997. Economic valuation of some wetland outputs of Mud Lake
Minnesota-South Dakota. Ag. Econ. Report #381, Department of Agricultural
Economics, North Dakota State University, Fargo.
Sierra Club. 1997. Red River Rampage: How restoring wetlands and moving homes from
floodplains can reduce future flood risk. A Report by the Sierra Club (Midwest Office)
and the Clean Water Network, May, 1997.
Sierra Club. 1998. Red River Valley: Future Flooding or Sensible Solutions? How Basin Wide
Coordination and Wetland Protection Can Reduce the Risk of Flooding in the Red River
Valley. Report by the Agassiz Basin Group of the Sierra Club, Sheridan WY, August 3,
1998.
Sip, R. L. 1998. An Economic Assessment of Wetland Mitigation in Northwest Minnesota.
Master’s Thesis, Department of Agricultural Economics, North Dakota State University,
Fargo.
Terry, K., and L. Aadland. 1997. Unpublihsed DNR Memorandum dated August, 1997.
U.S. Army Corps of Engineers. 1976. Natural Valley Storage: A partnership with Nature. New
England Division, Waltham Massachusetts.
U.S. Army Corps of Engineers. 1978. Interim Feasibility Study, Red River of the North Main
Stem, Hydrologic Data. St. Paul District, St. Paul, Minnesota, 49 p.
U.S. Army Corps of Engineers. 1980. Red River of the North Reconnaissance Report-Wild Rice
Marsh Rivers Subbasin. St. Paul District, St. Paul, Minnesota.
U.S. Army Corps of Engineers. 1994. Sharing the Challenge: Floodplain Management into the
21st Century. Report of the Interagency Floodplain Management Review Committee to
the Administration Floodplain Management Taskforce. Washington, DC.
U.S. Army Corps of Engineers. 1998. 404 Permit for Maple River Dam Draft Environmental
Impact Statement. Omaha District, Nebraska.
47
Appendix A: Abbreviations Used in the Report
AF
Acre Feet
ASAP
Available Storage Acreage Program
BWSR
Board of Water and Soil Resources
CACFDAS
Computerized Agricultural Crop Flood Damage Assessment System
CCJWRD
Cass County Joint Water Resources District
DEIS
Draft Environmental Impact Statement
DNR
Department of Natural Resources
EBI
Environmental Benefits Index
FEMA
Federal Emergency Management Agency
GIS
Geographical Information Systems
NDSWC
North Dakota State Water Commission
NWI
National Wetlands Inventory
RIM
Reinvest In Minnesota
RRV
Red River Valley
USFWS
United States Fish and Wildlife Service
USGS
United States Geological Society
WRW
Wild Rice Watershed
WRWMB
Wild Rice Watershed Management Board
48
Appendix B:
Impoundment-Storage Programs in North Dakota and Minnesota
1) The Devils Lake ASAP Program in North Dakota
In the Devils Lake area of North Dakota, the Governor’s Emergency Plan for Action,
which includes the Available Storage Acreage Program (ASAP), was initiated in 1996. The plan
is intended to help reduce flooding associated with high water levels in Devils Lake, which is
located in northeastern North Dakota, approximately 90 miles west of Grand Forks, North
Dakota (NDSWC, 1997).
At the time of inception, the upper-basin storage component had a potential storage
capacity of approximately 75,000 AF, which could hypothetically reduce the lake level by
approximately one foot. The goal of the ‘smaller tract water storage’ portion of the ASAP
program is to store approximately 35,000 AF by creating smaller tracts of water storage on
available public and private lands. This part of the component is called the Available Storage
Acreage Program (ASAP).
ASAP’s inception was a joint effort between the North Dakota State Water Commission
and pertinent federal agencies having jurisdiction in water-related issues. The federal agencies
involved include: 1) Natural Resources Conservation Service (NRCS), 2) U.S. Department of
Agriculture (USDA), 3) U.S. Army Corps of Engineers (USACE), 4) U.S. Fish and Wildlife
Service (USFWS), and 5) Environmental Protection Agency (EPA). Under agreement by the
aforementioned authorized agencies, the newly created water storage areas and the expanded or
restored wetlands will not be regulated provided three criteria are adhered to.
The following guidelines and rules have been applied to the ASAP program:
1) One-year leases will be negotiated to retain floodwater. Lease extensions may be
available if funding is available and it is agreeable to the landowner.
2) Only land areas that contribute water to Devils Lake are eligible for ASAP.
3) The NDSWC evaluates sites on the basis of cost to implement, lease cost, and volume
of water stored. Since program funding is limited, areas holding the largest volumes
of water for the least amount of money will be given first priority. Payment will be
made only for acres flooded.
4) Approved participants will be offered ASAP contracts. The participant will be paid
the contract price after spring runoff was captured at the site verification is completed
by NDSWC staff.
5) For sites involving multiple landowners, all affected landowners must agree to
participate and are eligible for payment for any impacted land.
6) Water control structures will be earthen berms or drain plugs with or without gated
control at the landowner’s preference.
7) Control structures will be left in place after the agreement expires for landowners to
use as they wish. If removal of the structure is desired at the end of the lease, it will
49
be the responsibility of the landowner and should be reflected in the bid.
8) Landowners may use the land immediately adjacent to the impounded water as they
wish; there is no upland requirement.
9) ASAP does not provide or require the replanting of the water retention area after the
agreement expires.
10) Agreement has been secured to ensure nonwetland areas will not become classified as
jurisdictional wetlands.
11) Landowners who are interested in participating in ASAP should submit an application
to the NDSWC or the Devils Lake Joint Board. The application is nonbinding.
ASAP stored approximately 8,000 AF of water in 1996. Approximately 22,000 and
21,000 AF of water were stored, respectively, in 1997 and 1998 (NDSWC, 1998). As of January
15, 1999, it was estimated that inflows into Devils Lake were reduced by approximately 40,00050,000 AF, which kept the lake from rising about four to five inches (NDSWC, 1999).
The minimum lease payment for ASAP was set at $50 per acre (NDSWC, 1996).
Governor Schafer determined this payment level in December 1995 after hearing comments from
three public meetings. Actual payments are a function of the landowner’s bid and volume of
water storage. Although ASAP compensated landowners based on competitive bids, the need for
water storage was greater than the interest. Therefore, most landowners received the maximum
payment for water withheld (NDSWC, 1999). The maximum payment was set according to the
damage the volume of water would expect to have caused if added to Devils Lake. At that time,
75,000 AF of water added to Devils Lake would have caused a one-foot rise at a cost of $5
million, which equated to $60 per AF (NDSWC, 1999). The maximum payment was reduced to
$50 per AF as the basin became wetter and interest among landowners grew. This value is
approximately 170% higher than average rental rates in the area (as reported by the North
Dakota Agricultural Statistics Service). The difference between average rental rates and the
ASAP payments is considered a price ‘premium’ that farmers require due to uncertainty
concerning the potential effects of water storage on the long- term productivity and value of
agricultural land. However, this premium might be relatively high because apparently, many
farmers in the region knew in advance the maximum rental payments the state would be willing
to make.
Presently, however, the damage caused by a one-foot increase in Devils Lake would
equate to approximately 100,000 AF and cause an average of $25 million in damage (NDSWC,
1999). Current annual water storage in ASAP is approximately 20,000-22,000 AF. With the
current lake levels, costs beyond the current storage levels would likely increase rapidly and may
not be considered feasible (NDSWC, 1999).
Through 1998, approximately $2,578,000 has been spent on ASAP. An additional
$950,000 has been allocated for 1999 ASAP. Costs are primarily for payments to participants,
though secondary costs involve preparation of sites. Approximately $430,000 was spent on
water storage in 1996 with 1997 site renewal costing $403,000. Sites completed in the fall of
1996 cost $47,000, while sites originated in 1997 cost approximately $691,000 (NDSWC, 1997).
ASAP was allocated $1,150,000 for 1998 of which roughly $1,000,000 was spent (NDSWC,
1997, 1998).
50
2) The Proposed Wild Rice Storage Program
The Wild Rice Watershed Management Board (WRWMB) is currently developing a pilot
project utilizing natural water storage areas in the upper watershed to reduce local and watershed
flood damage. More specifically, the project identifies natural water detention sites in areas that
are linked to downstream flood damage and where only minor structural changes and
improvements are necessary to enhance the water storage capabilities at these sites. Flood
storage easements are then intended to be purchased which would involve regular flood-storage
activities.
According to Houston Engineering (1999), the primary project benefits would include: 1)
flood protection, 2) water quality improvement, 3) erosion control, 4) wildlife habitat
enhancement, 5) recreational opportunities, and 6) aesthetic enhancement.
Flood protection should be enhanced through the project's water storage sites, which are
intended to reduce peak flows downstream through runoff retention near its origin. Retained
runoff will then be slowly released, reducing peak flows, decreasing erosion, and reducing
downstream property damage. It is also hypothesized that a variety of related water quality,
wildlife, and recreational benefits will result from the project (Houston Engineering, 1999).
The specific rules of the easement involve farmers providing the WRWMB the right of
entry and exit to paid-for lands for the purposes of structural construction and maintenance and
the right to retain runoff on the land until a suitable time for controlled discharge.
Possible storage sites will be selected based on location in the upper watershed,
geophysical land characteristics, and overall cost effectiveness of the flood storage site. The
location should provide the maximum potential flood storage with the least amount of structural
improvements. Utilizing existing topography, soil characteristics, and natural water retention
areas will help to reach this criterion. The overall cost-effectiveness of each site will be
measured as a function of project costs and volume of water storage obtained. According to
Houston Engineering (1999), if overall costs are less than $1,000/AF of storage obtained, the
project could be deemed feasible. As a guideline, this measure would take into account the
entire project rather than be limited to individual detention sites within the project.
Easement acquisition will be a multi-step procedure contingent on previous steps:
1. Problem identification is the first step in the procedure and targets existing drainage
problems. Often landowners are the best source identifying drainage problems. Therefore
public advertising of the program is vital. In addition to landowners, township, county, state,
federal, and private organizations all can be beneficial in problem identification.
2. After drainage problems have been identified, the specific storage site(s) will be identified
and proposed. USGS quadrangle maps, aerial photos, and other methods will be essential for
this step in order to identify approximate flood pool sizes, affected areas, and affected
landowners. This is required in order to meet with landowners.
3. Once a problem and corresponding storage area has been identified, representatives from the
Watershed District will meet with the affected landowner(s) to determine interest in the
51
project. Though only a rough conceptual framework will be known at this point, enough
information should be available for a landowner to determine interest or lack of in the
program. Individuals and circumstances vary and, therefore, some may require more
information in order to feel comfortable with an informed decision. The main objective at
this stage is to gain an option for an easement or purchase agreement for the required land if
the land is deemed feasible before proceeding to the next step.
4. The option for easement or purchase allows the process to continue with assurance that the
landowner has agreed to the easement or purchase of the land if determined to be feasible.
This guarantees that future funds will not be expended studying unavailable sites. Upon
attainment of this option, a detailed survey of the site can be initiated, including preliminary
design, a cost estimate, and a hydrologic and hydraulic analysis.
5. Overall cost effectiveness of the site(s) in storing water will determine the decision to
continue or abandon the project. The cost estimate will need to include but not be limited to
construction, engineering, administration, legal counsel, land acquisition, permitting, and
meetings (Houston Engineering, 1999). A preliminary guideline of $1,000/AF of storage or
less will determine the cost effectiveness of the project.
6. If a decision to implement the project is determined, the option(s) for easement/purchase will
be exercised. Once legal obligations are finalized, final design and construction can be
implemented.
A variety of regulations, situations, and locations will likely be encountered with
potential water storage sites, including lands currently participating in government programs
such as the Conservation Reserve Program (CRP). Therefore, it is necessary to have a dynamic
rather than a uniform payment system. Following is a list addressing potential situations and
recommended actions:
1. Flood Storage Easement:
The easement is the primary proposed method of flood storage acquisition. The landowner
retains ownership of the property and may continue to use for agricultural and recreational
purposes. The easement will be purchased at a price not to exceed the County Assessor’s
Township Average Market Value available annually through the Minnesota Department of
Revenue, or the individual parcel assessed value as recorded by the county auditor (Houston
Engineering, 1999). The landowner will continue to pay property taxes on the land while the
easement will be transferred to the Watershed District for the life of the agreement.
2. Fee Simple Land Purchase:
In this situation, the land would become the property of the Watershed District with all
landowner rights and responsibilities being transferred from the landowner to the Watershed
District. Payment for the land would follow the same criterion previously outlined.
3. Flood Storage Easement on lands currently involved in CRP:
The land acquisition method will need to meet the usage requirements of the CRP contract.
CRP payments for individuals are based on the duration of the contract and the bid the
52
landowner had approved upon acceptance into the program. Due to this variation, flood
storage easements would be based on the value for adjacent land not enrolled in CRP or a
similar program. The price paid would follow the previously outlined criterion. In the event
the landowner prefers to sell the land parcel rather than granting an easement, the purchase
price would be the same as the easement price and the CRP contract would transfer to the
Watershed District (Houston Engineering, 1999).
It should be noted that there is some debate whether land enrolled in CRP can be used for
water storage. The main question focuses on whether water storage would be incongruent with
the accepted bid and resulting CRP contract. Currently, there is not a consensus on this issue. It
can be reasonably argued that water storage on current and new CRP contracts likely would not
be allowable within the framework of the contract as signed. However, expiring contracts that
are up for continuous renewal or future sign-ups may allow water storage if written into the
contract. The answer likely will come from the interpretation of how water storage is viewed
within the Environmental Benefits Index (EBI) of the CRP bid.
4. Flood Storage Easements on existing Reinvest In Minnesota (RIM) program lands:
Acquiring flood storage easements on existing RIM lands would require coordination and
approval through the Board of Water and Soil Resources (BWSR). RIM program
requirements would need to be met in addition to approval of the overall flood storage plan.
Once again, the price paid would follow the previously outlined criterion.
Criteria for design and construction of the water storage sites will be based on the
“Minnesota Wetland Restoration Guide,” (1992), prepared by the Minnesota Board of Water and
Soil Resources. Though the guide addresses both flood control and wildlife production, flood
control is the primary objective of this project. Therefore, recommendations for flood control
will be emphasized though designs may vary from site to site and from the guide. Deviations
from the guide will be followed if deemed advisable by a licensed professional engineer.
Each design will depend on location, topography, available storage, and costeffectiveness. Earthen embankments and principal and emergency spillway systems will be the
primary methods for water control. The principal spillway controls inflow and outflow from the
detention site while the emergency spillway safely discharges runoff that exceeds the maximum
capacity of the site (Houston Engineering, 1999).
Monitoring Procedures:
Monitoring will be the responsibility of the Wild Rice Watershed District and consists of
inspections and maintenance. Specifically, inspections will be based on criteria set forth in the
“Minnesota Wetland Restoration Guide,” (1992). These criteria emphasize seasonal inspections
for three years following initial construction.
Inspections should also follow any flood events. Observations and corrective actions or
plans should be documented. Following the first three years, inspections should be performed
annually in May or June, after major flood events, or after any condition that may negatively
affect the integrity of the site.
53