Upper Snake River Basin
Water Stewardship Assessment
4/15/2014
Upper Snake River Basin Water Stewardship Assessment
1. EXECUTIVE SUMMARY
1.1
PURPOSE
Concerns about the adequacy of water supplies in the Upper Snake River Basin date nearly from the
start of the first irrigation withdrawals in the late 1800s. Considerable documentation describes the
development of irrigated agriculture and the resultant complexities of surface water and ground
water management in the area, particularly at the basin scale. This report presents a view of these
challenges through a particular lens—companies with significant but indirect agricultural
dependency.
The purpose of this report is to assess the major water resource challenges and opportunities
within the Upper Snake River Basin. This water resource assessment is then evaluated from the risk
perspective of companies that depend on agricultural products. There is considerable interest in
both fostering sound water stewardship and mitigating possible supply chain risks for companies
that source crops in the region. We propose recommendations towards achieving both these goals.
Importantly, we also identify key stakeholders that must be engaged throughout the
implementation of water stewardship activities.
1.2
BASIN REVIEW
The Upper Snake River Basin is characterized by one of the largest and most productive aquifers in
the country. Even in the absence of development, the Eastern Snake Plain Aquifer (ESPA) is highly
connected to surface water, both gaining from and losing water to streams and creeks throughout
the aquifer.
Within this complex hydrologic backdrop developed one of the most productive agricultural
regions in the country. Beginning in the late 1800s, extensive irrigation systems were built to
compensate for inadequate growing-season precipitation. With the construction of major
reservoirs, agriculture expanded quickly in the first half of the 20th century. Agricultural
development has created a highly modified water balance within the basin, diverting large volumes
of surface water for irrigation and incidentally increasing aquifer storage in the process.
By the 1950s, new pump and irrigation technology allowed farmers to more easily irrigate cropland
with ESPA groundwater. In the 1970s and 1980s, improvements in irrigation efficiency reduced
incidental recharge from surface irrigation. Periods of severe drought also occurred in the past
several decades. These events reversed the trajectory of aquifer storage and began a trend of
aquifer depletion that continues today. Declines in ESPA storage levels have in turn resulted in
decreased discharges from groundwater to surface water.
In light of declining aquifer storage, the Conjunctive Aquifer Management Plan (CAMP) was
developed by the State of Idaho to comprehensively manage the basin to mitigate future water risk.
The plan proposes implementation of specific mitigation activities over the next 30 years, including
aquifer recharge, groundwater to surface water conversion, and demand reduction.
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Upper Snake River Basin Water Stewardship Assessment
1.3
SUSTAINABILITY ASSESSMENT
As a result of declining ESPA discharges to springs and streams, surface water users have begun to
face significant water shortages. In order to protect their water rights, these surface water users
have sought regulatory relief through the curtailment of junior water rights held by ESPA
groundwater users. The outcome is an environment of increasing water supply insecurity,
particularly for groundwater users.
Growers in the Upper Snake River Basin face a number of additional water-related risks in addition
to water scarcity.
•
•
•
Water quality concerns continue to grow in the basin, particularly regarding nutrient and
sediment pollution in the Twin Falls area.
Fish and wildlife are increasingly vulnerable to decreased stream flows and reduced water
quality.
Future climate change is expected to increase water scarcity through decreased snowfall
and increased temperatures.
The complexities of conjunctive (both surface and ground water) management necessarily tie the
fates of all water users in the basin. While groundwater-dependent users are already being
impacted, all water users in the basin will face increasing uncertainty—whether due to decreased
water availability or the impacts of potential future litigation and regulation.
1.4
WATER STEWARDSHIP RECOMMENDATIONS
For companies engaged in water stewardship in the agricultural supply chain, the most immediate
question is how to mitigate anticipated water resource impacts in order to reduce risks to growers.
We identify four categories of possible water stewardship activities: stakeholder engagement,
water quantity mitigation, water quality improvement, and fish and wildlife protection. These
categories correspond to the major sources of risk. Within these categories, there are on-field and
off-field opportunities to implement water stewardship activities.
Implementation of the CAMP, already in its fifth year, has established a clear set of water resource
management priorities and determined the primary measures for implementation. As feasible,
corporate water stewardship activities should be aligned with this effort, leveraging existing
stakeholder buy-in to achieve outcomes that both reduce supply chain risks and support CAMP
objectives.
A key conclusion of this assessment is that improvements in irrigation efficiency must be
considered carefully with regard to potential impacts—both beneficial and adverse. For
groundwater users, there are likely limited opportunities for significant efficiency gains. For surface
water users, changes in irrigation practices could further exacerbate water shortages. Such changes
need to be considered with respect to overall basin sustainability, local hydrologic conditions, and
the significance of co-benefits such as pollution mitigation.
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Upper Snake River Basin Water Stewardship Assessment
Outlined below are general water stewardship actions that can be developed by companies to
support supply chain risk mitigation in the Upper Snake River Basin. These recommendations are
intended to guide the development of more detailed stewardship planning efforts.
(1) Clarify water stewardship objectives relative to the identified categories of water risk and the
scale of desired sustainability outcomes.
(2) Engage stakeholders to develop a coordinated action plan for corporate water stewardship
activities in the basin.
(3) Coordinate with the CAMP implementation process and multi-stakeholder committee to ensure
alignment of objectives.
(4) Assess water supply sources and on-field practices for supply chain connected growers to
determine risk mitigation potential.
(5) Prioritize on-field water use activities that maximize co-benefits such as reduced pollutant
loading or increased stream flows.
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Upper Snake River Basin Water Stewardship Assessment
CONTENTS
1.
EXECUTIVE SUMMARY .............................................................................................................................. 2
1.1
1.2
1.3
1.4
2.
INTRODUCTION ........................................................................................................................................... 6
2.1
2.2
3.
Watershed overview ................................................................................................................................... 7
Water resources......................................................................................................................................... 10
Water use ..................................................................................................................................................... 16
Water administration and management............................................................................................ 20
PART II: SUSTAINABILITY ASSESSMENT AND STEWARDSHIP PLANNING..........................26
4.1
4.2
4.3
5.
Overview ......................................................................................................................................................... 6
Approach.......................................................................................................................................................... 6
PART I: BASIN REVIEW ............................................................................................................................... 7
3.1
3.2
3.3
3.4
4.
Purpose............................................................................................................................................................. 2
Basin review.................................................................................................................................................... 2
Sustainability assessment .......................................................................................................................... 3
Water stewardship recommendations.................................................................................................. 3
Sustainability assessment ....................................................................................................................... 26
Stewardship planning ............................................................................................................................... 32
Conclusions .................................................................................................................................................. 41
REFERENCES ................................................................................................................................................ 44
Prepared by The Nature Conservancy with support from the General Mills Foundation.
Special thanks to Rob Van Kirk from the Henry’s Fork Foundation who contributed significant
review and discussion to support this report.
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Upper Snake River Basin Water Stewardship Assessment
2. INTRODUCTION
2.1
OVERVIEW
This report presents a sustainability assessment and stewardship plan for the Upper Snake River
Basin in Idaho. The Upper Snake River Basin was selected due to its significance as a major growing
region in a basin with apparent water availability concerns. Part I provides an overview of water
resources in the Upper Snake River Basin. This section of the report also describes the governance
and management landscape. Part II presents an assessment of water resource sustainability relative
to current and future risks. The report then reviews the major types of stewardship activities that
could mitigate this water risk. The report concludes with recommendations for companies that
recognize the value in corporate stewardship for mitigating water risk.
2.2
APPROACH
The Upper Snake River Basin is undeniably a complex water system, whether in terms of hydrologic
processes or water allocation. Describing the full complexity of the basin and its management is
beyond the scope of this report. In defining the purpose of this document, we have chosen an
approach that focuses on identifying the key challenges most relevant to corporate water
stewardship and supply chain considerations in the Upper Snake River Basin.
The original proposal for this assessment focused on the eastern plain area from Rexburg to
American Falls. However, hydrologic and administrative boundaries generally include a larger
geographic area. Accordingly, the available information and data sources reported here generally
refer to Upper Snake River Basin at large or the Eastern Snake River Plain Aquifer.
For this assessment, we have utilized reports and research from key institutions in the basin
including Idaho Department of Water Resources (IDWR), U.S. Geological Survey (USGS), and the
University of Idaho. We have also consulted expert opinion from key stakeholders involved in the
science and management of the basin.
The results and recommendations presented in this report are intended to describe the range of
available opportunities for corporate water stewardship. Additional planning processes will be
necessary to further define specific stewardship actions.
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Upper Snake River Basin Water Stewardship Assessment
3. PART I: BASIN REVIEW
3.1
WATERSHED OVERVIEW
3.1.1 Basin at a glance
The Idaho segment of the Upper Snake River Basin1 extends from basin headwaters at the
Wyoming border to King Hill, where the river emerges from a deep canyon incised into lava rock.
Major hydrologic components include the Snake River, the Eastern Snake River Plain Aquifer
(ESPA), Malad River drainage, and Salmon Falls Creek (Figure 1). The basin covers an area of
approximately 35,800 square miles in eastern Idaho—more than 40% of the state—with the ESPA
itself comprising 10,800 square miles of that total (Van Kirk 2008, Konikow 2013).
More than 500,000 people live in the Upper Snake River Basin. The most recent State inventory of
the basin indicates that the population is increasing at a modest annual rate of 1-2 percent (IWRB
1998).
The climate is arid to semiarid with sagebrush and bunch grasses dominating the natural
landscape. Within the eastern plain, annual precipitation is low (8 to 10 in.). Precipitation during
the growing season is negligible with the system largely dependent on winter and early spring
precipitation in tributary watersheds. Mountain ranges north and east of the ESPA receive 40 to 60
inches of precipitation annually, primarily as snowfall (IWRB 1998, USGS 1992). A smaller but still
significant amount of precipitation falls on mountain ranges to the south. Regional and global
climate variability also drive precipitation (Van Kirk 2008). Several periods of widespread drought
have occurred in the past 100 years including periods of severe drought in 1987–1992 and 2000–
2007 (USACE 2009, Wise 2010).
One of the most prominent hydrologic features of the Upper Snake system is the strong connection
between surface and ground water. Tributaries to the north and east of the ESPA (approximately
from Ashton to Sun Valley) terminate on the eastern Snake Plain and infiltrate into the large
volcanic rock aquifer. The Snake River itself alternately contributes to and receives water from the
aquifer, depending on water table elevation and underlying geology.
The Idaho segment of the Upper Snake River Basin is defined hydrologically as the region draining to the USGS gauge at
King Hill. Using this area allows for the full accounting of inflows and outflows within the basin, including groundwater. A
more restricted area upstream of Milner dam is also referred to as the “upper Snake River”. This area corresponds to the
administrative boundaries for all points of diversion and storage upstream of Milner dam. In this report, the “Upper Snake
River Basin” will refer to the larger area extending from headwaters to King Hill.
1
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Upper Snake River Basin Water Stewardship Assessment
Figure 1. Map of the Upper Snake River Basin within Idaho. Also shown are Snake River tributaries and the ESPA
boundary (solid black line). From Idaho Department of Water Resources (IDWR).
3.1.2 Agriculture and industry
Agriculture and related agricultural services remain the primary economic drivers in the basin with
an estimated $10 billion in goods and services generated annually. Agriculture is both the largest
sector of the area economy and the biggest consumptive user of water. In the upper Snake basin,
there are nearly 2.9 million acres of harvested cropland which includes more than 2.4 million acres
of irrigated land. 2 The four largest crops by annual harvested area are hay, wheat, barley and
potatoes (Table 1).
2
Derived using county-level data from the 2007 USDA Census of Agriculture.
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Upper Snake River Basin Water Stewardship Assessment
Crop
Acres harvested
Percent of total
Hay
917,567
32%
Wheat
664,789
23%
Barley
459,753
16%
Potatoes
289,680
10%
Corn
248,032
9%
Sugar beets
150,065
5%
Beans
42,782
1%
Other
121,723
4%
Table 1. Annual crop totals by acre harvested for the primary agricultural crops in Upper Snake River Basin
counties (2007 USDA Census of Agriculture).
Figure 2. Estimated growing locations for the region’s major crop types in the Upper Snake River Basin. Cropland
estimates are for the year 2012 and provided by the USDA Cropland Data Layer Program.
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Upper Snake River Basin Water Stewardship Assessment
Throughout the basin, hay and grains dominate the agricultural landscape (Figure 2). Adjacent to
and downstream of American Falls Reservoir, sugar beets, beans and corn are also important
commodities.
In addition to agriculture, dairy production and aquaculture are also important to the regional food
production industry. According to current estimates, the aquaculture industry in Idaho ranks as one
of the largest in the country producing 75% of domestically farmed trout. In the Upper Snake River
Basin, aquaculture facilities are concentrated in the Thousands Spring reach area near Twin Falls.
These businesses are highly dependent on sufficient and high quality spring discharge from the
ESPA (Slaughter 2012).
Major hydropower facilities also exist in the Upper Snake River Basin accounting for roughly a third
of the state’s hydroelectric production (total capacity is approximately 700 megawatts) (IWRB
1998). The largest hydropower facilities by total capacity are shown in Table 2. Hydropower
production is dependent primarily on reservoir operations and spring and early summer runoff.
Additional hydropower facilities further downstream on the Snake River are also dependent on
basin flows.
Facility name
Palisades
Stream
Snake River
Capacity (MW)
176.6
American Falls
Snake River
92.3
Bliss
Snake River
75.0
Lower Salmon
Snake River
60.0
Milner
Snake River
59.5
Twin Falls
Snake River
43.7
Upper Salmon
Snake River
34.5
Gem State
Snake River
23.4
Malad
Malad River
21.7
Table 2. Major hydroelectric facilities by total capacity in the Upper Snake River Basin (after IWRB 1998).
3.2
WATER RESOURCES
3.2.1 Water availability
Surface water
Within the basin, surface water processes are highly modified from base or natural flow conditions.
Natural streamflow conditions that were once driven primarily by snowmelt have since become
carefully managed through diversions and reservoir operation in order to satisfy water user rights
(Van Kirk 2008).
In terms of total discharge, the headwaters of the Snake River account for the majority of
streamflow within the Upper Snake River Basin (Figure 3). The Henrys Fork is also an important
tributary to the system accounting for more than a quarter of average annual discharge. Additional
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Upper Snake River Basin Water Stewardship Assessment
tributaries along the perimeter of the ESPA account for the remainder of streamflow within the
system.
Figure 3. Schematic representation of the relative contribution of average annual discharge within the Upper
Snake River Basin, where thicker blue lines indicate greater reach discharge (from Cosgrove 2006).
Natural surface flows are driven primarily by mountain snow accumulations with the majority of
rainfall being lost as evapotranspiration (Van Kirk 2008). Under natural streamflow conditions,
discharges are highest in the late spring during snowmelt and lowest during fall and winter. The
result of flow regulation for irrigation and power generation purposes has been the augmentation
(increase) of base flows while peak flows have been diminished.
The largest storage reservoirs within the basin are located along the main stem of the Snake River
(Table 3). More than two-thirds of all reservoirs in the basin are operated by U.S. Bureau of
Reclamation, primarily serving purposes of irrigation and flood control. Additional objectives
include power generation, municipal and industrial withdrawals, recreation, and instream flows for
fish and wildlife. The management of storage reservoirs (i.e. the timing of filling and spilling) is
highly dependent upon the seniority of water rights. Additional discussion on water rights
administration is provided later in this report.
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Upper Snake River Basin Water Stewardship Assessment
Reservoir
Completed
Stream
Purpose
American Falls
1978
Snake River
Palisades
1957
Snake River
Jackson Lake
Blackfoot
Salmon Falls
Island Park
Lake Walcott
Henrys Lake
1916
1911
1911
1938
1906
1910
Snake River
Blackfoot River
Salmon Falls Creek
Henrys Fork
Snake River
Henry's Lake Outlet
Ririe
1976
Willow Creek
Oakley
Milner
1916
1906
Goose Creek
Snake River
Irrigation, Power
Irrigation, Flood,
Power, Recreation
Irrigation, Flood
Irrigation, Municipal
Irrigation
Irrigation
Irrigation, Power
Irrigation
Irrigation, Flood,
Recreation
Irrigation
Irrigation, Power
Storage (ac-ft)
1,672,600
1,200,000
847,000
350,000
182,700
135,200
95,200
90,400
80,500
77,400
50,000
Table 3. Reservoirs in the Upper Snake River Basin with storage greater than 50,000 ac-ft, listed in order of
decreasing storage (after IWRB 1998).
Groundwater
Geologically, the ESPA is characterized by a history of volcanic activity. Following periodic episodes
of explosive volcanism associated with the Yellowstone hotspot, basaltic lava flowed across the
plain, becoming interspersed with gravel and ash. These basalt-dominated layers are highly
permeable to water and have created the conditions for one the largest and most accessible
aquifers in the United States (Konikow 2013). Wells drilled in the area indicate that the effective
aquifer depth is approximately 800-1,200 feet. Below this depth, geologic layers become
increasingly dense with less water storing capacity.
While generally considered to be highly permeable and unconfined, there remains considerable
heterogeneity within the aquifer geology (Garabedian 1992). Gravel and sand dominate the fringes
of the aquifer plain and are also associated with deposits of silt and clay. These deposits are less
permissive of water movement and can lead to locally isolated areas of perched or confined water
tables. Even in the central region of the Eastern Snake Plain dominated by basaltic rock, water
movement is non-uniform. Groundwater flow or conductivity tends to be the greatest along the
direction of lava flows and within basalt layer gaps. The general trajectory of water flow is
southwesterly but actual flow directions and velocities are highly dependent upon localized
geologic conditions (Figure 4). This is important to note when considering water management
actions since the timing and magnitude of specific hydrologic outcomes are not readily
generalizable.
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Upper Snake River Basin Water Stewardship Assessment
Figure 4. Generalized directions of groundwater flow in the ESPA area (from Graham and Campbell, 1981).
Due to the highly permissive underlying geology, the ESPA is a dynamic system with continual
fluxes in water storage. In contrast to confined or fossil aquifers, the ESPA water balance is
significantly influenced by recharge pathways. Aquifer recharge is dominated by incidental
recharge through irrigation losses—tributary underflow, precipitation, and streamflow seepage
also playing an important role. With irrigation losses accounting for more than half of the annual
aquifer recharge, the overall picture of the ESPA is a highly modified system influenced heavily by
agricultural water use practices.
Surface and groundwater interaction
The dominant hydrological characteristic of the basin is the dynamic interaction of surface and
groundwater. Along the length of the Snake River within the basin, the river and its tributaries
alternately gain and lose water between the larger ESPA and smaller perched aquifers. Additionally,
the direction and magnitude of these interchanges are often dependent upon stream flow volumes
and water table elevations. These patterns of surface and groundwater interaction have been well
described (IWRB 1998). But while the general patterns of connectivity are understood, the complex
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Upper Snake River Basin Water Stewardship Assessment
interactions of location, stream flow, and groundwater levels mean that predicting the impacts of
water management activities is highly context specific. For example, groundwater recharge
activities may actually augment stream flow rather than contribute to aquifer storage.
In addition to surface water interactions, the ESPA also feeds important springs near the American
Falls and Thousand Springs reaches of the Snake River. Discharge from these springs is
significant—Thousands Springs alone accounts for almost 40 percent of ESPA discharge (IWRB
1998). Below Milner dam, these springs can account for the entire flow within the Snake River.
Discharge at these springs is directly dependent upon aquifer storage, with higher discharges
occurring at higher aquifer storage levels.
3.2.2 Water quality
Surface water quality
In keeping with other water resource elements of the basin, the view of surface water quality
concerns is similarly mixed in the Upper Snake River Basin. In general, pollutants increase in
concentration in the downstream direction throughout the basin (Clark 1994). In particular,
pollutant concentrations are the highest at the mouths of tributary basins and in the reach between
Milner and King Hill (also known as the Middle Snake River).
In terms of pollutant types, nutrients, sediment, and pesticides are the most common contaminants
and all three are highly associated with agricultural practices. Farm fertilizer application
contributes more than two-thirds of the total budget for both nitrogen and phosphorous. Similarly,
evidence indicates that on-field practices can have significant impacts on sediment loads (IWRB
1998). Reservoirs act as sediment and nutrient sinks, concealing the full impact of land use
practices.
The most recent spatial data set available from the Idaho Beneficial Use Reconnaissance Program
(BURP) indicates that more than 70% of assessed streams and lakes do not meet beneficial use
criteria. 3 Of these assessed streams, more than 5,000 miles of streams are listed as 303(d) impaired
waters requiring determination of formal pollution limits. Causes for impairment determinations
include sediment, nutrients, pesticides, dissolved oxygen, thermal modification, habitat alteration,
and flow alteration. Several pollutant limits have already been developed for reaches throughout
the basin. The first pollutant limits or TMDLs (total maximum daily loads) were established for
reductions in total phosphorous with a recent status update report indicating that concentrations
have decreased very little (IDEQ 2013). Additional limits are expected to be phased in for other
pollutants including nitrogen and flow alteration.
A basin perspective indicates that agriculture is a major driver of water quality concerns in addition
to other point sources such as livestock production, food processing, and aquaculture operations.
The scale of these water quality impacts is heavily dependent on streamflow and connected aquifer
Beneficial use criteria are established by the State for specific stream reaches and lakes. Categories of beneficial use
include water supply, aquatic life, recreation, wildlife habitats, and aesthetics (IDEQ 2014).
3
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Upper Snake River Basin Water Stewardship Assessment
spring discharge. Considerable work remains for adequately mitigating pollutant concerns and the
agricultural sector will likely be an important stakeholder in this effort.
Figure 5. Current status (2010) of streams and lakes in the Upper Snake River Basin. Waters determined to be “not
supporting” of one or more beneficial use categories are highlighted in red. Data from IDEQ.
Groundwater quality
National, state, and regional groundwater quality programs have conducted monitoring in the
Upper Snake River Basin with most of the sampling focused on the Eastern Snake River Plain.
Overall groundwater quality in the basin is considered to be good in large measure due to the sheer
size of the aquifer and the relatively high recharge rate. However, there exist localized areas of
water quality pollution.
The vulnerability of groundwater supplies to pollutants is dependent on four primary drivers:
water table elevation, recharge or infiltration rate, soil type, and land use activities (IWRB 1998). A
review of the ESPA by Idaho’s Department of Environmental Quality (IDEQ) in 1991 found that
areas of greatest vulnerability were irrigated cropland with shallow or perched aquifers
underneath. Compounding concern about these most vulnerable areas is the fact that most
domestic wells source water from shallower groundwater depths.
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Upper Snake River Basin Water Stewardship Assessment
Nitrate levels are a particular concern across the ESPA with possible sources including fertilizers,
decaying organic matter, livestock facilities, and sewage discharge (IWRB 1998). Areas most
affected are located along the aquifer margins and the Thousand Springs area. The springs in
particular have been a focal area for continued monitoring after the observance of increasing
nitrate levels during the 1990s (IDEQ 2006). Estimates of nitrogen loading indicate that fertilizer
application and other agricultural activities may contribute more than half of total nitrate loads.
Other pollutants of concern in the ESPA are pesticides related to agriculture. Statewide monitoring
projects have focused on locations with both groundwater vulnerability and pesticide use.
Monitoring results in the Magic Valley area (near Twin Falls) indicated the detection of pesticides at
several well locations (ISDA 2009). The USGS National Aquifer Water Quality Assessment (NAWQA)
program has conducted a more comprehensive look at water quality in the ESPA (Frans 2012). Well
sampling beginning in 1992 has monitored 87 different pesticides. At least half of the sampled wells
indicated the presence of pesticides. The herbicide atrazine was the most commonly detected
pesticide, found in both domestic and public-supply wells. However, well samples indicated
contaminant levels were significantly below health concern thresholds.
3.3
WATER USE
3.3.1 History of water use
The history of water use in the Upper Snake River Basin is closely intertwined with American
settlement and the development of irrigated agriculture. Beginning with the 1862 Homestead Act,
national policy has driven the establishment of one of the country’s most significant agricultural
areas within an otherwise semi-arid landscape (Slaughter 2004). Even before the advent of federal
irrigation development programs, more than 300,000 acres of the basin were irrigated by surface
flow diversions (largely in the Henrys Fork, Upper Snake River, and Wood Rivers) (Garabedian
1992). By the early 1900s, diversions for irrigation demand were large enough to deplete entire
reaches of the Snake River (IWRB 1998). After passage of the 1902 Reclamation Act, land
development policy was buttressed with the construction of reservoirs, providing the necessary
enabling conditions for the agriculturally productive Upper Snake River Basin of today.
By the middle of the 20th century, most of the significant reservoir storage had been developed (Van
Kirk 2008). By this time, more than 500,000 acres were farmed using surface water diversions for
primarily flood and furrow irrigation. Total diversions were roughly 8 to 10 million acre-feet with
much of the irrigation water infiltrating into the aquifer or returning as stream flows (Garabedian
1992). An elaborate system of canals—primarily unlined with high leakage rates—had been built to
carry surface water to irrigated land. During this period, total ESPA storage actually increased
above baseline levels due to incidental infiltration of excess canal leakage and irrigation water.
Around this time, two significant changes in water use occurred. The first development was an
increase in the use of groundwater. Some of this groundwater was used to irrigate new farmland; in
other areas, farmers switched from surface to ground water supply (Figure 6).
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Upper Snake River Basin Water Stewardship Assessment
Figure 6. Historical changes in surface and ground water acreage in the ESPA (from Cosgrove 2006 after
Garabedian 1992).
Concurrent with increasing use of ESPA groundwater was a transition from gravity to sprinkler
irrigation. This increase in sprinkler irrigation was initially attributable primarily to groundwater
users but gained adoption by surface water users as well (Garabedian 1992). Irrigation application
efficiencies significantly increased while maintaining crop production levels (IWRB 1998). In part
as a result of these efficiency gains, surface water diversions began to decrease in the 1970s and
this trajectory continues today. These decreased surface water diversions have in turn decreased
the flow of irrigation-related infiltration to the aquifer.
The net result of these two changes—increased groundwater abstraction and decreased recharge
incidental to surface irrigation—has been a significant shift in the trajectory of ESPA storage.
Previous agricultural practices had steadily increased the available groundwater supply through
infiltration of surface water into the aquifer. Mid-century changes in irrigation practices
precipitated a decline in aquifer storage for the first time since major farming activities began in the
basin. This continuing trajectory of aquifer storage is well evidenced through changes in aquifer
storage elevations since 1980 (Figure 7).
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Upper Snake River Basin Water Stewardship Assessment
Figure 7. Map showing groundwater elevation changes in the ESPA from 1980–2008 (from IWRB 2011).
3.3.2 Current water use
Agriculture remains the largest water user—both in terms of total withdrawal and consumptive
use—within the Upper Snake River Basin (Figure 8) (ESPA CAMP 2009). Currently, there are some
2.4 million acres of irrigated land in the basin including 2.1 million acres within the ESPA boundary
(Van Kirk 2008, ESPA CAMP 2009). Approximately 1 million acres are irrigated with surface water
upstream of Milner Dam and another 0.8 million acres are irrigated with ground water from the
ESPA. The remainder (0.6 million acres) is irrigated with a combination of surface and ground
water including tributaries on the perimeter of the ESPA.
In terms of total volume, an estimated 10.1 million acre-feet is withdrawn annually for irrigation
(Van Kirk 2008). More than half this total volume—about 6.6 million acre-feet—returns to the
system as aquifer recharge or return flows. The consumptive fraction of irrigation water use is
estimated at 3.7 million acre-feet annually, or roughly a third of total withdrawals.
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Upper Snake River Basin Water Stewardship Assessment
Figure 8. Estimates of sector water withdrawals for all 24 counties within the Upper Snake River Basin. Left panel
shows surface and ground water withdrawals in millions of gallons per day (Mgal/d) where numeric values indicate
total (surface plus ground) withdrawals. Right panel indicates sector withdrawals relative to overall surface and
ground water totals. Data are estimates from the USGS National Water Use Information Program in 2005.
Domestic, commercial, municipal, and industrial (DCMI) water use accounts for approximately
400,000 acre-feet annually (IWRB 1998). This figure includes a wide range of activities including
household use, public supply, food processing including sugar refining and potato processing, Idaho
National Engineering and Environmental Laboratory (INEEL) water use, and a range of commercial
water users. Fish hatcheries are the largest DCMI water user throughout the basin (235,000 acrefeet in 1995). Relative to agriculture, DCMI is a small water user though projections expect this use
to increase with future population growth (IWRB 2009).
Basin irrigation flows
Volume
(million acre-feet)
WITHDRAWALS
Surface water in Water District 1
7.3
Groundwater from ESPA
1.2
All other surface and ground water
1.6
Total
RETURNS
10.1
Infiltration to ESPA
4.0
Other irrigation returns
2.6
Total
6.6
Table 4. Mean irrigation related flows within the Upper Snake River Basin from 1958-2007 (after Van Kirk 2008).
While irrigation continues to be the primary water user in the basin, other non-consumptive water
users are also economically significant (Van Kirk 2008). Hydropower generation is also important
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Upper Snake River Basin Water Stewardship Assessment
water user and factors significantly in the management of reservoirs (Van Kirk 2008). Additionally,
an economically important recreational fishing industry is dependent upon surface water flows,
particularly in the upper tributaries of the basin (Loomis 2006).
3.4
WATER ADMINISTRATION AND MANAGEMENT
3.4.1 Water rights
Historically, water rights were established simply by meeting beneficial use requirements. 4 Since
1963 for groundwater and 1971 for surface water, water rights can only be established through a
formal permitting and licensing procedures (IDWR 2014). Following the prior appropriation
doctrine, Idaho manages rights according to the “first in time is first in right” approach typical of
many western states (Tuthill 2013). Under this system, water is delivered in order of decreasing
priority where the oldest water rights have the highest priority.
In 1987, IDWR began administering an adjudication process to formally define all water rights in
the Upper Snake River Basin including historical or beneficial use rights. Since 1992, the Idaho
Department of Water Resources has maintained a moratorium on the processing and approval of
water development permits in the Snake River Basin above Weiser (IWRB 1998). The basin is
considered closed, precluding the addition of new significant water users (some exceptions exist for
domestic, stock, and municipal users).
In the Upper Snake River Basin, three categories of water rights exist: natural flow, storage water,
and groundwater. Within the basin, more senior natural streamflow rights are located
predominantly in the Magic Valley area downstream of Milner and in the Henrys Fork Basin. Almost
all groundwater rights are junior to both natural flow and storage water rights. Each type of water
right is administered differently:
•
•
•
Natural flow rights refer to diversions of natural stream or spring flows and are
quantified in terms of instantaneous stream discharge (cubic-feet per second).
Storage water rights refer to surface water stored in and released from reservoirs.
Storage water rights are quantified in terms of annual storage (acre-feet per year).
Groundwater rights are quantified in terms of pumping rates (cubic-feet per second).
Water rights are additionally defined with regard to the purpose, season of use, point of diversion,
and place of use. For most irrigation water rights, water use is restricted to the growing season
from April through October. While water rights are generally associated with real property rights, it
may be possible to transfer or change a right relative to the point of diversion, place of use, period
Beneficial uses include irrigation, stock-watering, manufacturing, mining, hydropower, municipal use, aquaculture,
recreation, and fish and wildlife (IDWR 2014).
4
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Upper Snake River Basin Water Stewardship Assessment
of use, or nature of use. Such changes require formal consideration by IDWR to ensure, among other
considerations, that the change does not injure other water rights. 5
Previously, surface water rights were managed separately from groundwater. Events in the 1990s
and early 2000s set in motion a shift towards joint or conjunctive management of both surface and
ground water. 6 The water rights adjudication process initiated in 1987 led IDWR to exercise
authority over groundwater rights administration in the Thousand Springs and American Falls
areas. Also around this time, concerns were growing about the impact of groundwater pumping on
spring flows, eventually culminating in legal petitions or “delivery calls” by senior surface water
users against groundwater users (Slaughter 2012).
As a result of these changes, both surface and groundwater diversions are now conjunctively
managed according to water right priority dates. In years when insufficient water is available to
meet all water rights, IDWR seeks to mitigate impacts to senior water users through an
administrative process that includes the possibility for negotiation, mitigation, or curtailment. In
this environment of water insecurity, groundwater users have sought to protect their rights
through litigation and mitigation (Slaughter 2012).
One avenue for groundwater mitigation has been the purchase of unused reservoir water (Whelan
2013). Storage water right holders can lease their rights into a State managed rental pool. Under
threat of curtailment, groundwater users have utilized this rental pool water to mitigate the
impacts of pumping on surface water flows in the Thousand Springs area (Patton 2012). While
rental pool water offers the opportunity to offset surface water discharge impacts, there is
considerable uncertainty with this approach. Such mitigation is dependent on adequate water
availability and subject to administrative restrictions including priority for certain users and point
of use locations (IDWR 2013).
The end result of the shift to conjunctive management is an environment of considerable
uncertainty and risk. The existing administrative and legal tools offer incomplete, and costly,
remedies for addressing these conflicts.
3.4.2 Water institutions and management
There are a number of institutions, both state and private, that are responsible for the management
and delivery of water resources. Described below are the key organizations that play an active role
in basin water management activities.
IDWR utilizes a complex spreadsheet tool based on aquifer modeling data in order to determine the hydrologic impacts
resulting from any proposed water right change.
5
The legal basis for conjunctive surface and ground water management is codified in the 1951 Idaho Ground Water Act
which called for restrictions where groundwater abstraction affects senior water rights or is in excess of natural recharge
rates.
6
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Upper Snake River Basin Water Stewardship Assessment
Idaho Department of Water Resources
The Idaho Department of Water Resources (IDWR) is the primary State agency responsible for the
management of water resources. IDWR manages a number of programs including comprehensive
basin planning, minimum stream flow assessment, water project financing, water supply banks and
water rentals. In the Upper Snake River Basin, IDWR also oversees the delivery and distribution of
water through the authority of water districts.
Idaho Water Resources Board
The Idaho Water Resource Board (IWRB) was created by the Idaho Legislature in 1965. Comprised
of eight members appointed by the governor, the Board was initially charged with development and
implementation of the state water plan. In 1974, the Board and the existing Department of Water
Administration were combined to form the present-day Idaho Department of Water Resources.
The Board, with assistance from IDWR Planning and Technical Division staff, is involved in court
appeals, adoption of administrative rules, water bank administration, state water planning, and
negotiations with the Federal government and Indian Tribes.
Bureau of Reclamation
The US Bureau of Reclamation manages eight dams through its Upper Snake Field Office: Little
Wood River, American Falls, Grassy Lake, Island Park, Jackson Lake, Minidoka, Palisades, and Ririe
Dams. Reclamation manages these dams primarily for irrigation purposes (based on water rights)
but also considers secondary factors such as flood control, hydropower, fish and wildlife, and
recreation (Van Kirk 2008). Reservoir operation rule curves can have significant impacts on stream
flow in reaches throughout the basin.
Water is stored in the reservoir system and accrued to storage water rights according to the prior
appropriation system. Generally, water is stored in the highest-elevation reservoirs first regardless
of where the water right is held. To the greatest extent possible, downstream reservoirs are
depleted first, regardless of the physical location of the water right. If and when a storage right is
exhausted, the user may obtain and use additional storage water, if available, through the Upper
Snake rental pool. The practice of storing water as high in the system as possible throughout the
year maximizes water availability and minimizes the probability that water will be spilled at Milner
Dam. 7
State water districts
The State has created water districts, overseen by Watermasters, which are responsible for
delivering water to ditches, canals, and other diversion points (Tuthill 2013). Water District 1 is the
largest in the state and includes most of the Upper Snake River Basin upstream of Milner Dam.
Actual water allocations are determined on a daily basis utilizing a computer-based system to
manage the more than 300 diversion points (IDWR 1997). The general procedure is to “calculate
The Snake Basin has historically been managed according to the “two rivers” concept, whereby all flows upstream of
Milner dam are managed independently of those downstream. The result is to effectively set a zero flow target at Milner
dam (Tuthill 2013, Van Kirk 2013). Additionally, this has important implications for the management of water rights
whereby upstream appropriations are managed independently from those downstream.
7
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Upper Snake River Basin Water Stewardship Assessment
natural flows, allocate those flows in order of priority… and then determine stored water used and
storage supplies remaining”.
Beginning in 2002, water districts have also been created for the management of groundwater
distribution. Watermasters in these districts are responsible for diversion monitoring and
enforcement of mitigation or curtailment actions (Tuthill 2013).
Irrigation districts
One of the oldest formal water user groups, irrigation districts primarily serve to develop irrigation
projects including construction of canals and other infrastructure (IDWR 2014). These districts also
oversee the delivery of water to irrigation users. An important distinction is made between state
authorized irrigation districts versus canal companies which are private corporations with the
primary function of delivering water to shareholder members. In the Upper Snake River Basin,
there are at least 10 irrigation districts and nearly 100 private irrigation companies (Van Kirk
2013).
Ground water districts
Similar to irrigation districts, ground water districts are organized groups of groundwater users
having state authority to construct and operate water resource projects (Tuthill 2013, IDWR 2014).
One of the primary purposes of ground water districts is to “develop and operate mitigation plans
designed to mitigate” adverse impacts to senior water uses caused by groundwater abstraction.
Such mitigation activities typically include the acquisition of unused water and the implementation
of aquifer recharge projects. Nine ground water districts have been established within the ESPA.
3.4.3 Conjunctive Aquifer Management Plan
With projections of decreasing aquifer storage and growing conflicts between senior and junior
water users, the State legislature directed the Idaho Water Resources Board to develop a
comprehensive management plan for the ESPA. The Conjunctive Aquifer Management Plan (CAMP)
is the result of this process and describes the goals, objectives, and proposed implementation
actions for aquifer management (IWRB 2009). The plan recommendations reflect the perspectives
of a broad group of stakeholders and serve to balance feasibility constraints with improvements in
water management outcomes, focused primarily on securing adequate water supply for all users. 8
The CAMP establishes short and long-term targets for managing water use within the ESPA towards
“stabilizing and improving spring flows, aquifer levels, and river flows” (Table 5). This phased
implementation process reflects the complexity of the system and the need to carefully monitor the
impact of implemented measures. The short-term or Phase I target is an annual increase in aquifer
storage by 300,000 acre-feet within the first 10 years of implementation. The long-term target for
aquifer storage is an annual increase of 600,000 acre-feet by 2030.
It is important to note that environmental objectives (including environmental flows) are not well defined within the
context of CAMP (Whelan 2013). Allowance is made within adaptive management provisions for further defining
environmentally-related activities and outcomes.
8
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Upper Snake River Basin Water Stewardship Assessment
The cost estimate for implementing Phase I is estimated at $70–100 million over 10 years.
Achieving the long-term objective is estimated to cost more than $600 million. Importantly, the
CAMP recommendations are largely unfunded with proposed water user funding still under
development. There exists considerable interest in developing alternative funding mechanisms to
achieve these objectives including participation from private businesses (Tuthill 2012).
Action
Ground to surface water conversion
Managed aquifer recharge
Demand reduction
Surface water conservation
Crop mix modification
CREP and other fallowing
Buy outs and buy downs
Weather modification
Short-term annual target
(thousand acre-feet)
100
100
50
5
40
No target
50
Long-term annual target
(thousand acre-feet)
100
150-250
250-350
No target
Table 5. Summary of proposed activities and associated annual hydrologic targets for CAMP short- and long-term
objectives (after IWRB 2009).
The most recent progress report on CAMP implementation indicates that more than $52 million has
been spent on aquifer management activities since plan inception (IWRB 2013). Activities
amounting to more than 175,000 acre-feet per year have been successfully implemented. These
activities are comprised primarily of managed aquifer recharge (117,111 acre-feet per year on
average) with contributions from ground water conversion and demand reduction (Table 6).
Importantly, not all management activities will have equivalent outcomes on aquifer storage. There
is continued debate regarding the impact of aquifer recharge activities with some experts indicating
that recharge activities above American Falls may not significantly increase long-term storage
(Kruesi 2012).
Irrespective of the quantitative outcomes to date, the CAMP process has been highly successful in
demonstrating the feasibility of a collaborative and comprehensive approach to water management
in the Upper Snake River Basin. The State and other stakeholders have made significant time and
monetary investments to develop this plan. Where previously water user groups were atomized
and uncoordinated, the State has successfully implemented an established planning and
implementation framework supported by a diverse group of stakeholders. This effort presents an
ideal opportunity to engage in water stewardship within the basin—indeed, successfully
implementing water stewardship activities outside of this framework would likely be difficult.
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Upper Snake River Basin Water Stewardship Assessment
Table 6. Progress on CAMP implementation from 2009–2012. Note that volumes are not necessarily reflective of
direct increases in aquifer storage levels (from IWRB 2013).
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Upper Snake River Basin Water Stewardship Assessment
4. PART II: SUSTAINABILITY ASSESSMENT AND STEWARDSHIP
PLANNING
4.1
SUSTAINABILITY ASSESSMENT
Given the complexities of hydrology and management within the basin, it is not possible to point to
a single sustainability metric. Rather, it is necessary to consider physical water resource constraints
(water quantity and quality) within the greater sociological context (regulation, management, and
economic development) in order to characterize the future of water within the upper basin.
Highlighted below are the most significant water-related impacts expected to affect agricultural
production throughout the basin.
4.1.1 Aquifer depletion
Assessment of the sustainability of the Upper Snake River Basin reveals a system which has been
characterized as over-allocated except in years of above average precipitation (Whelan 2013). The
water budget deficit is most readily revealed by the trajectory of ESPA groundwater levels. Since
the 1950s, groundwater levels have been declining at an annual rate of at least 200,000 acre-feet
(Table 7). The current shortfall is likely even larger given the trajectory of increasing groundwater
abstraction, decreasing incidental surface water infiltration, and decreased water availability 9
(Figure 9).
Aquifer storage flows
Volume
(million acre-feet)
INFLOW
Irrigation infiltration
4.0
Tributary underflow and river seepage
2.2
Eastern tributaries
0.7
Total
OUTFLOW
6.9
Spring discharge
5.9
Groundwater pumping
1.2
Total
7.1
NET CHANGE
-0.2
Table 7. Estimated average annual water budget for the Eastern Snake River Plain Aquifer (ESPA) from 1958-2007
(after Van Kirk 2008). Updated estimates for current values would show a greater annual deficit due to smaller
values for irrigation infiltration and spring discharge and larger values for pumping.
9
In addition to changes in water use, aquifer storage is also highly responsive to drought conditions (IWRRI 2004).
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Upper Snake River Basin Water Stewardship Assessment
Figure 9. Cumulative change in aquifer storage for the ESPA from 1912-2008 (figure from IWRB 2013).From 1952–
1980, aquifer storage declined by 204,000 acre-feet per year. Since 1980, aquifer storage has declined by
approximately 220,000 acre-feet per year (from IWRB 2013).
If current trends in water use and availability continue, it can be expected that aquifer storage
levels will return to pre-irrigation levels by 2035. 10 Beyond that point, continued groundwater
abstraction will deplete aquifer storage below even pre-irrigation levels.
4.1.2 Water user conflict
In terms of risk, aquifer depletion is not the most immediate concern as total storage is estimated to
be at least 200-300 million acre-feet, roughly the size of Lake Erie (IDEQ 2006b). Rather, it is
departure from peak aquifer storage levels and the consequent effects on surface water users that
is primarily driving management concerns. While total aquifer storage levels remain above preirrigation levels, the decrease in cumulative storage has already impacted water users dependent
on ESPA spring discharges. It is estimated that changes in water use practices have collectively
decreased spring discharge and stream flows by more than 1.4 million acre-feet annually since the
1950s (Johnson 1999, IDWR 1997). In particular, groundwater pumping is estimated to have
depleted annual discharges by 900,000 acre-feet.
The situation is further affected by inter-annual precipitation variability, with wet and dry years
driven by decadal climate patterns and long-term climate change (Van Kirk 2008). In years with
above average precipitation, few shortages exist for any water users (Van Kirk 2013). In average or
below average years, curtailment or other mitigation is necessary in order to ensure the fulfilment
of more senior surface water rights.
This assumes that changes in water use and availability continue. It is more probable that a new equilibrium or steady
state will be reached where water use practices stabilize. However, changes in availability will still impact aquifer storage.
10
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Upper Snake River Basin Water Stewardship Assessment
Water rights were appropriated in accordance with the prevailing hydrologic conditions at that
time. As such, water rights are necessarily dependent upon these historical water balance
conditions. In the case of some natural flow users, fulfillment of their water right allocations is
directly dependent upon adequate ESPA spring discharge which is in turn driven by groundwater
elevations. The decline in aquifer levels since the 1950s has had the effect of reducing spring and
stream flows and consequently impacting the ability of surface water users to utilize their full water
rights (Figure 10).
Figure 10. Spring discharges below Milner Dam are driven by ESPA storage levels and have been heavily influenced
by irrigation returns flows infiltrating into the aquifer. Since 1950, spring discharges have begun decreasing as
groundwater use and irrigation efficiency increased (from Clark 1998).
That groundwater pumping has contributed to the decline in aquifer storage and the consequent
decreases in spring discharge is not disputed. Given the detailed hydrologic monitoring and
modeling developed for management of the ESPA, it is even possible to estimate the magnitude of
these impacts attributable to groundwater pumping. However, groundwater abstraction is not the
only factor causing the decline in aquifer levels. As discussed previously in History of water use,
changes in irrigation practices have caused declines in incidental groundwater recharge and played
a part in declining aquifer levels.
Conflict first culminated in 1993 when spring water users near Hagerman formally petitioned
IDWR requesting curtailment of water withdrawals from junior water users (IWRRI 2012). Since
then, several litigious actions have been brought forth including a contentious 2005 petition made
by aquaculture businesses in the Thousand Springs area (Poppino 2008). That delivery call
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Upper Snake River Basin Water Stewardship Assessment
threatened to curtail groundwater irrigation for more than 50,000 acres of farmland. The case was
ultimately brought before the Idaho Supreme Court which ruled in favor of the aquaculture
businesses, reaffirming the primacy of priority appropriation irrespective of the severity of adverse
economic impacts on junior groundwater pumpers (AP 2011). The organization representing these
groundwater users was ultimately able to mitigate pumping impacts through the purchase of one of
the aquaculture businesses for an undisclosed but likely sizeable fee (Poppino 2011).
While three of the largest legal actions between surface and groundwater users have recently been
settled, the prospect of future conflicts is almost certain without major changes in water
management. Groundwater users in the Upper Snake River Basin operate under continuous threat
of curtailment depending on surface water use and seasonal precipitation availability. As aquifer
levels continue to decline, water users both directly and indirectly dependent on spring flows will
face increasing water resource risks. The complexities of conjunctive management necessarily tie
the fates of all water users in the basin, both surface and ground water. While groundwaterdependent users are already being impacted, all water users in the basin will face increasing
uncertainty—whether due to decreased water availability or the cost and uncertainty of future
litigation and regulation.
Another major downstream water user, Idaho Power, also holds significant natural flow water
rights with priority senior to many groundwater irrigators in the Upper Snake River Basin. The
result of a complex settlement between the State of Idaho and Idaho Power, the Swan Falls
agreement specifies seasonal minimum stream flows in order to protect hydropower water rights
for Idaho Power (IDWR 2012). Groundwater users in the Swan Falls “Trust Water Area” have rights
subordinate to these minimum stream flows (Figure 11). As aquifer storage levels continue to
decline with corresponding decreases in ESPA discharges, groundwater users could also face
curtailment in order meet these minimum stream flow obligations. The impacts of such curtailment
would be far reaching, affecting all groundwater users with a priority date after October 25, 1984.
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Upper Snake River Basin Water Stewardship Assessment
Figure 11. The Swan Falls agreement potential curtailment area if minimum stream flows at Murphy gage are not
met. From IDWR 2012.
4.1.3 Fish and wildlife impacts
In addition to supporting water-dependent businesses, aquifer-fed spring discharges are also
important for supporting aquatic wildlife including sensitive fish and mollusk species (IWRB 2008).
Beyond the immediate vicinity of the spring creeks and estuaries, this water is also important for
maintaining summer base flows and improving water quality in the reach below Milner dam (IWRB
2008b). Wildlife species in this reach are vulnerable to several water quality threats including
nutrient pollution, increased sediment, and elevated water temperatures. ESPA springs discharge
cool, clean water that dilutes water pollutants while supplementing low summer stream flows
when aquatic wildlife is most vulnerable. Additional stream reaches are also impacted by irrigationrelated water diversions (see Surface water), including the operation of surface water reservoirs
(Van Kirk 2008).
The cumulative effect of water resource management over the previous century has been a
decrease in native trout populations and an increase in nonnative fishes. Instream conditions
deteriorate significantly from headwaters to the basin outlet at King Hill, driven by both decreasing
flows and declining water quality (Figure 12) (Clark 1998).
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Upper Snake River Basin Water Stewardship Assessment
Figure 12. Assessment of fish population integrity or quality as compared to natural conditions in the Upper Snake
River Basin. Instream conditions generally decline from headwaters to the basin outlet (from Clark 1998).
Most environmental actions to date have been focused on migratory fish habitat conditions in the
Lower Snake River below King Hill (Van Kirk 2008). 11 As water stress in the basin continues to
increase and water quality further degrades, aquatic wildlife is likely to garner greater attention
including the possible need for mitigation or remediation. While attribution of specific
environmental impacts is highly dependent on local parameters, the overall result is greater
uncertainty with regard to water availability. Given the economic importance of maintaining the
overall health of aquatic wildlife in the Snake River, it is likely that environmental considerations
will continue to play an important role in balancing competing interests (IWRB 2009).
4.1.4 Water quality pollution
From the perspective of water security, there is significant potential for increased restrictions in
order to mitigate or control water quality impairment. While water quantity issues dominate
concerns in the Upper Snake River Basin, water quality impacts are also significant. As presented in
Water quality, agriculture has significant impacts on water quality, delivering increased nutrient
Stemming from the Nez Pearce agreement and biological opinions first issued in 2005, USBR now actively manages
reservoir operations to improve habitat for listed and critical fish species (USBR 2013).
11
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Upper Snake River Basin Water Stewardship Assessment
and sediment loads into streams and creeks. Additional impacts on ground water quality, the
widespread presence of pesticides in particular, are also of concern.
Since the early 1990s, the growth of large algal mats and other invasive plants has prompted water
quality concerns in the Middle Snake River from Milner to King Hill (IDEQ 2013). Total
phosphorous TMDL was subsequently developed and point-source operations—primarily
aquaculture and municipal treatment facilities—have largely been successfully in reducing
phosphorous loading (EPA 2008). However, target phosphorous levels have still not been met.
The situation is further compounded by the impact of reduced spring discharges and consequent
stream flows. When developing the TMDL for this reach, IDEQ made assumptions regarding stream
discharges (IDEQ 2013). Since the TMDL was last revised in 2005, spring discharge and stream
flows have consistently been lower than predicted. The net effect is greater concentrations of
phosphorous relative to reduced flow volumes. This adds an additional dimension to water
resource management by specifically linking ground water quantity to surface water quality
impacts. The implications of this connection for conjunctive management are yet to be fully
understood.
To date, most activities to improve water quality have focused on point sources. However, some
programs, including several managed by USDA, have implemented a number of on-field activities to
mitigate water quality impacts throughout the ESPA and greater basin (USDA 2011). As water
quality targets continue to be exceeded, it is likely that greater attention will be given to the
development of more systematic mechanisms for controlling or mitigating agricultural runoff.
4.1.5 Climate change
Regional climate analyses indicate that water stress will increase in the Upper Snake River Basin as
a result of climate change (Hamlet 2007, IWRB 2012). Higher temperatures will increase crop
water demands and result in increased consumptive use (at current crop production levels). A
warmer climate will also drive a shift from snowfall to rain. The decreased snowpack is expected to
result in lower runoff in the summer and fall, essentially reducing the amount of stored water
available at these times of year. Additional storage mechanisms (e.g. new reservoirs or aquifer
recharge) will be necessary to offset this predicted deficit.
The cumulative impact of future climate change is expected to further increase pressure on farmers
and other water users in the basin. Irrigation demands will increase while peak growing season
water availability will decrease due to lower snowpack levels. These projections for climate-driven
changes in demand and availability have not been explicitly addressed within the CAMP (IWRB
2009). While the immediate concern in the basin is present day water availability, addressing
future climate-related risks will be important for ensuring the sustainable use of water resources.
4.2
STEWARDSHIP PLANNING
The most immediate question at hand is how to mitigate the anticipated water resource impacts
described previously in order to reduce risks to growers and their sourcing companies. Mitigation
could span a range of activities, from informing policy or management to directly supporting the
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Upper Snake River Basin Water Stewardship Assessment
implementation of on-field practices or technology. Implementation of the CAMP, already in its fifth
year, has established a clear set of water resource management objectives and describes the
primary means and measures for effecting this change. The major opportunity then is to engage
within or augment this established framework, leveraging existing stakeholder buy-in in order to
achieve outcomes that both reduce supply chain risks and support CAMP objectives.
Outlined below are four categories of possible entry points into the corporate water stewardship
landscape within the Upper Snake River Basin: stakeholder engagement, water quantity mitigation,
water quality improvement, and fish and wildlife protection. These categories generally correspond
to the major sources of risk discussed above. Importantly, we consider the significance of these
possible stewardship activities relative to the CAMP objectives, which is necessary for ensuring
coherency with broader basin objectives and overall water resource sustainability.
4.2.1 Engaging with stakeholders
Align objectives with the CAMP process
An important step for the development of any water stewardship activities in the Upper Snake
River Basin is to engage with the established CAMP implementation process. A carryover from the
original CAMP Advisory Committee, the Implementation Committee includes representatives from
a variety of water user groups, business interests, municipalities, government agencies, and
nongovernmental organizations.
Engaging with the existing CAMP process offers several important advantages for developing
corporate stewardship activities including multi-sectoral stakeholder participation, a long-term
vision of sustainable water resource planning, and an adaptive planning approach. By coordinating
with this established authority, companies engaging in water stewardship activities can both
validate proposed actions and leverage existing partnerships to better facilitate project
implementation. While it may not be possible or necessary to affiliate directly with the committee,
there are several key partners that are already established within the CAMP process such as
growers and conservation groups (including TNC staff). These key partners can help facilitate the
consideration of specific corporate water stewardship activities within the context of CAMP
implementation.
Strengthen stakeholder relationships
While the ESPA CAMP is the most significant multi-stakeholder consortium in the basin, other
stakeholder groups and institutions also make important contributions to water management in the
basin. Where objectives align, companies should engage these organizations to leverage
opportunities for funding and implementation at scale. A brief overview of key stakeholder groups
and initiatives is described below.
Field To Market
The Field To Market effort tracks quantitative outcomes from changes in farming practices aimed at
improving a range of sustainability outcomes. Most relevant to the management of water resources,
the initiative is working with a group of growers to pilot farm practices that maintain or improve
yields while reducing water withdrawals.
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Upper Snake River Basin Water Stewardship Assessment
Continued support for the Field To Market initiative could be an important mechanism for
providing evidence that supports specific changes in water use practices. Scientific papers and
project reports based on activities implemented in locations outside of Idaho have limited capacity
to demonstrate efficacy or convince farmers. By collecting information about farm outcomes that
are directly relevant to other farmers in the Upper Snake River Basin, the Field To Market initiative
establishes a unique position of credibility.
Opportunities may exist to further expand grower participation and the relevancy of results from
the Field To Market initiative. For example, the initiative could pilot particular grower practices
(discussed below in Mitigating water quantity risk) that have immediate relevancy for CAMP
objectives. In particular, the initiative could develop projects that demonstrate the feasibility and
efficacy of reducing consumptive use requirements or improving water quality outcomes. By
linking Field To Market activities to the broader CAMP implementation effort, companies can better
bring to scale the adoption of important evidence-based grower practices.
200 Bushel Club
Besides the Field To Market initiative, other efforts are also underway in Eastern Idaho to optimize
crop production. The 200 Bushel Club challenges growers to increase wheat yields through
adopting new farming practices. While this yield goal may not be economically practical for most
wheat farmers, the information collected through this initiative may provide valuable insights into
particular farming practices that could sustain yields while reducing water use. Connecting with
these farmers may also be a strategic avenue for the future implementation of on-field measures
and practices to mitigate water resource impacts.
Water districts and other water user groups
Irrigation and Groundwater Districts represent the immediate water interests of participating
growers throughout the basin. These formally recognized water user groups have considerable
implementation capacity, both in terms of membership and financial support. Especially where
anticipated stewardship activities are located within these districts, it will be important to engage
directly with these groups outside of the CAMP process to ensure the alignment of objectives.
A private water user organization, Idaho Ground Water Appropriators (IGWA), represents at least
ten ground water districts and irrigation districts, municipal, commercial, and industrial
groundwater users including food processors (IGWA 2007). Particularly where stewardship
activities may focus on the actions of groundwater users, IGWA will be an important stakeholder.
Natural Resources Conservation Service
Under the administration of the USDA, the Natural Resources Conservation Service (NRCS)
manages a number of programs targeted towards improving water management in the basin. These
programs are already providing important funding to improve water management in the basin.
These programs are subject to change with new farm bill funding cycles, but some of the most
relevant programs include:
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Upper Snake River Basin Water Stewardship Assessment
•
•
•
•
•
The Conservation Reserve Enhancement Program (CREP) works with farmers to voluntarily
remove cropland from production. CREP is included as an important mitigation activity for
achieving CAMP objectives.
The Environmental Quality Incentives Program (EQIP) provides financial and technical
assistance to farmers that implement conservation practices to improve water, soil, and
other natural resources.
The Agricultural Water Enhancement Program (AWEP) provides financial and technical
assistance to farmers in order to reduce water use and improve water quality.
Conservation Innovation Grants (CIG) support the development and adoption of innovative
conservation technologies and practices for agricultural production.
The Cooperative Conservation Partnership Initiative (CCPI) provides funding for
conservation activities on agricultural land in priority areas.
Catalyzing new actors
The CEO Water Mandate is a U.N. Global Compact initiative that supports the private sector in
understanding and addressing their impacts on water resources (CEO Water Mandate 2013). The
Mandate has described the key elements for implementing corporate water stewardship. Within
this framework, an important concept is the recognition that a single company cannot make
impacts at scale without engaging other actors. Engaging in this collective action can be one of the
most important contributions of corporate water stewardship.
As one of the most significant growing regions in the country (see Agriculture and industry), the
Upper Snake River Basin has important supply chain connections to a number of food, beverage,
and dairy companies. To date, there is no organization that collectively represents the concerns and
interests of these companies. The Nature Conservancy is already engaged with one company that
has strong supply chain connections to barley production in the upper basin. It is anticipated that
other major companies are sourcing significant quantities of agricultural products within the basin.
While crops and commodity relationship types may differ, the opportunity for synergistic
investments in water stewardship should be more thoroughly explored. Companies with vested
interest in sustainably sourcing priority ingredientsare well positioned to act as such a catalyst for
collective action in the Upper Snake River Basin.
4.2.2 Mitigating water quantity risk
On-field activities
For companies engaged in water stewardship in the agricultural supply chain, there is strong
interest and capacity for improving on-field practices and technology towards improving yields and
sustainability outcomes. Activities in other watersheds facing water stress have demonstrated
success in changing irrigation practices (TNC 2012).
In the Upper Snake River Basin, hydrologic connectivity adds a layer of complexity to the simple
calculus of targeting reduced irrigation water withdrawals. In this case, less efficient irrigation
practices (flood irrigation) created the conditions which have ultimately become the water
management objectives of CAMP. So while there may be opportunities to decrease irrigation
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Upper Snake River Basin Water Stewardship Assessment
withdrawals, such decreases may not actually mitigate water scarcity and could even exacerbate
shortages. 12
There are three important implications of hydrologic connectivity related to irrigation water use
and practices:
(1) Changes in irrigation practices are unlikely to significantly increase overall basin water
supply. Reducing water application rates primarily results in a shift between surface and
ground water without increasing overall water supply.
(2) While water withdrawals may be reduced through more accurate application of irrigation
water (e.g. using drip irrigation versus sprinkler), the impact on consumptive water use 13 is
less certain (Contor 2013, Perry 2009). Determining these impacts will require local, fieldbased testing of irrigation practices to measure reductions in non-beneficial consumptive
water use.
(3) Reduced irrigation withdrawals can affect outcomes besides overall basin water quantity.
Localized impacts can include increased stream flow and reduced water quality. These “cobenefits” can be an important driver of changes in irrigation practices (Gleick 2012, Van
Kirk 2013).
With these constraints in mind, below are categories of on-field stewardship activities that could
support water resource sustainability.
Reducing ESPA withdrawals through irrigation efficiency gains
While improving irrigation application efficiencies is unlikely to significantly increase overall water
supply, reducing ESPA withdrawals may contribute to rebalancing groundwater storage in
accordance with CAMP objectives. Several in-field practices and technologies have the potential to
reduce groundwater withdrawals (Table 8). The possible impacts of implementing such efficiency
measures are several:
(1)
(2)
(3)
(4)
(5)
(6)
Increased aquifer storage levels.
Reduced fuel consumption and related expenditures for groundwater pumping.
Reduced reliance on and expenditures for rental pool water (currently $17 per acre-foot).
Reduced exposure to senior priority water user delivery calls.
Decreased incidental return flows and infiltration.
Increased consumptive use.
To understand this challenge, it is necessary to consider that sustainability is assessed at the basin scale. Reducing the
withdrawal requirements for a given farmer through better irrigation may reduce his or her exposure to water scarcity.
However, from the perspective of the basin at large, overall water availability is unchanged. Where in other locations
irrigation runoff is often considered lost or wasted, in the Upper Snake River Basin, this water will likely return to the
aquifer or stream and subsequently be used again.
12
Consumptive water is the fraction of water use that is evaporated or transpired, collectively known as
evapotranspiration (ET). Such ET may be categorized as either beneficial or non-beneficial related to the intended
purpose of the water use.
13
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Upper Snake River Basin Water Stewardship Assessment
Improved irrigation efficiency for ESPA groundwater users generally results in beneficial outcomes.
However, some impacts (5 and 6 above) could result in greater water stress. Reduced return flows
as a result of decreased irrigation application rates could lead to increased conflicts with senior
priority water users that are dependent on this runoff. Another potential adverse outcome, some
empirical studies have observed an increase in consumptive use or evapotranspiration as a result of
improved irrigation application (Contor 2013, Frederiksen 2011). It is important to recognize that
any potential for water savings is highly dependent upon local circumstances (e.g. return flow
pathways) with many of the benefits not directly attributable to water quantity outcomes (e.g.
energy savings and reduced pollutant runoff).
Measure
Crop mix changes
Crop residue (mulch) or
polymers
Costs
Potential water
application
savings
Moderate
0–20%
Low
0–5%
Other
benefits
Notes
Change rotations to
crops with lower
crop water demands
(e.g. grains)
Increases soil
water holding
capacity
Limit end of season
irrigation
Low to moderate
0–10%
Energy and cost
savings
Range of possible
approaches,
including sight/feel,
water budgeting or
soil moisture probes
Low Energy Precision
Application (LEPA)
Moderate to high
0–10%
Good for windy
environments
Proper tillage
needed to reduce
runoff
No- or low-till
Low to moderate
0–10%
Energy, labor and
cost savings;
Reduces erosion
Requires machinery
upgrades
Moderate
0–10%
Energy and longterm cost savings
Low
5–15%
Energy and cost
savings
Renozzling of sprinklers
Shut off end guns
Aim for low pressure
systems with
nozzles closer to the
crops
Lost income can be
offset by energy
savings
Table 8. Example activities with potential to reduce applied irrigation water relative to sprinkler irrigation.
Reported efficiency gains are illustrative and highly dependent upon field-level conditions. Note that reductions in
applied water are not likely to reduce consumptive use. Adapted from unpublished TNC report.
An additional consideration is that ESPA groundwater users may already be operating at a high
level of irrigation efficiency (Van Kirk 2013). The energy costs of pumping groundwater have
provided economic incentive for minimizing withdrawals. Additionally, the direct conveyance of
groundwater to irrigation systems further limits opportunities for water savings.
Groundwater withdrawal reductions should be focused within the boundaries of the ESPA or at
locations where ESPA groundwater connections exists. Outside of these areas, reductions in
groundwater withdrawals would not address aquifer storage levels while potentially impacting
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Upper Snake River Basin Water Stewardship Assessment
downstream surface water users. Notably, the capacity for more efficient irrigation application to
affect aquifer storage levels has not been included within the current CAMP. This omission is likely
due in part to feasibility constraints including high investment costs relative to any potential
reduction in groundwater withdrawals.
Reducing non-beneficial consumptive use
While the utility and significance of irrigation efficiency gains are situation dependent, the positive
impacts of reducing non-beneficial consumptive use are generalizable across the basin. Nonbeneficial consumptive use is that portion of evaporated or transpired water that does not directly
benefit the intended crop. For example, evaporation from canals or weed transpiration can be
considered non-beneficial consumptive use. With consumptive use accounting for an estimated
3.71 million acre-feet, efficiency gains could be significant.
The challenge is to target consumptive use without impacting yields or reducing return flows. In
general, consumptive use tracks closely with yields (Humphreys 2010). However, there are some
on-field measures that have been shown to reduce non-beneficial consumptive use while
maintaining yields. Such measures could include low energy precision application (LEPA)
irrigation, mulching, or use of soil conditioners. Other measures, such as end gun shutoff or deficit
irrigation, may also reduce consumptive use but at the expense of decreases in harvestable yield.
Annual evaporative loss savings
Efficiency
measure
No-till or mulch
LEPA
Percent reduction
Wheat GW
irrigation (ac-ft)
All ESPA GW
irrigation (ac-ft)
Evaporative loss
fraction
Overall GW
water use
4,000
25,000
22,000
132,000
13%
75%
1%
6%
Table 9. Illustration of potential scale of water savings from practices aimed at reducing non-beneficial
consumptive loss (i.e. evaporative loss). Values should be considered maximal projections of evaporative loss
reductions given full and well-managed adoption. Efficiency data from Yonts 2006.
As demonstrated in Table 9, addressing evaporative loss has variable capacity for mitigating nonbeneficial consumptive use. The figures presented here are illustrative and do not address a
number of specific assumptions or considerations. This exercise demonstrates that, even
considering all groundwater irrigation withdrawals across the ESPA, the capacity for addressing
water use through evaporative loss mitigation is limited. 14 Additionally, such mitigation is likely
very costly to implement relative to other alternatives.
Such water saving benefits are also highly dependent upon specific climate, soil, plant physiology,
and field management parameters (Balwinder-Singh 2011). For example, water savings from LEPA
14 Field-level evaporative losses from sprinkler irrigation in the basin are estimated to be 3% of total withdrawal (Van
Kirk 2013). Other studies have identified similar net evaporative loss rates when accounting for the beneficial
(temperature cooling) effects of canopy evaporation (Tolk 1995).
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Upper Snake River Basin Water Stewardship Assessment
could be reduced significantly if proper field management techniques (e.g. furrowing or other
infiltration measures) are not followed. Additionally, reductions in soil evaporation can be offset by
increases in crop transpiration. Efforts to more accurately quantify the effects of such practices as
implemented by growers in Eastern Idaho could help prioritize any investments made to reduce
this non-beneficial water use.
Transitioning from incidental to managed aquifer recharge
There are also longer term opportunities to leverage on-field irrigation and conveyance efficiency
gains towards improving water quantity outcomes in the basin. Canal seepage 15 and irrigation
infiltration are currently the dominant aquifer recharge pathways. However, the location, timing,
and volume of this recharge is wholly incidental. In certain areas of the Eastern Plain, this incidental
recharge only serves to increase aquifer levels in the short term as such recharge is quickly
returned to streams and rivers (Johnson 1999). Transitioning from incidental to managed aquifer
recharge has the potential to increase longer term aquifer storage to the benefit of springdependent water users (Van Kirk 2013).
Implementing such a planned transition would require significant coordination, including changes
to existing water rights administration. 16 However, as existing sources of managed aquifer recharge
water become fully appropriated and utilized, there will be greater pressure to identify new
recharge sources. For companies beginning corporate water stewardship efforts in the basin, there
is an opportunity to engage early in the development of these potential activities.
Off-field activities
While on-field activities follow most directly from the supply chain interests of companies, there
may be important opportunities for mitigating water supply risk through off-field investments.
Akin to carbon offsets, such mitigation can directly and quantifiably compensate for water use
impacts. Unlike many carbon efforts, water impact mitigation through aquifer recharge measures
offers locally attributable benefits. While located off-field, such investments would directly support
farmers by reducing the risk of delivery calls from senior to junior water right holders.
Aquifer recharge
Within the basin, there are several opportunities for water stewardship investments away from the
farm. These off-field activities have the greatest potential for significantly mitigating water supply
risks. To date, the greatest increases in aquifer storage have been achieved through aquifer
recharge activities (see Conjunctive Aquifer Management Plan) (IWRB 2013). Assuming all
aquifer recharge water is equivalent, it is also the least expensive activity for rebalancing aquifer
storage (Table 10).
15
Canal seepage is estimated to account for 25-50% of total withdrawal (Van Kirk 2013).
The “use or lose it” provision of water rights disincentivizes implementation of conservation measures for natural flow
water users. Under existing water law, water conservation is not considered a beneficial use.
16
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Upper Snake River Basin Water Stewardship Assessment
Mitigation activity
Volume
(acre-feet)
Total cost
($ million)
Unit cost
($/acre-feet)
Managed recharge
117,111
1.258
10.74
GW to SW conversion
15,950
5.631
353.04
Demand reduction (CREP)
43,644
42.986
984.92
–
1.213
–
Weather modification
Table 10. Estimates of aquifer storage increases and related costs from 2009 to2012 for CAMP activities. Note that
volumes are not necessarily reflective of actual changes in aquifer storage (after ESPA CAMP 2013).
Despite the zero-flow requirement at Milner dam, there remains unallocated water that flows past
Milner dam in years where precipitation exceeds natural flow and storage water right allocations
(the average annual spill at Milner is 1.8 million acre-feet though this varies significantly between
years) (IWRB 2011). IWRB has targeted this unallocated flow in particular for use in aquifer
recharge projects. However, a greater constraint to the expansion of aquifer recharge may be an
agreement with Idaho Power that limits annual managed recharge activities to 100,000 acre-feet.
Policy measures
Besides direct investments in aquifer recharge activities, there is growing support for the
development of a market for groundwater banking (O’Connell 2013). Groundwater banking could
leverage voluntary trading to achieve several important outcomes including an increase in the
productive value of water and promoting conservation and recharge activities. Through such a
market, private water users, particularly surface water canal companies, would be able to receive
compensation for managed recharge projects that improve aquifer storage. This market-based
pathway could allow access to mitigation offsets directly to individual growers or other parties.
To date, several feasibility studies have been commissioned to assess possible implementation
constraints. In additional to political considerations, the connectivity of surface and groundwater
introduces additional complexity. A prerequisite would be a mechanism for comparing equivalency
of groundwater rights relative to surface water impacts (Contor 2010).
4.2.3 Reducing water quality impacts
Improving surface and ground water quality is perhaps the greatest potential benefits from on-field
practices and technology. While overall water availability is the most significant water risk within
the basin, there is potential for regulatory actions regarding water quality pollutants that could
impact growers. Especially in the Middle Snake River where TMDL implementation has been
unsuccessful in reducing phosphorous pollution, there is the possibility for increased restrictions.
Within the Upper Snake River Basin, TNC has worked with farmers to implement a number of onfield best practices to improve water quality. Efforts at the Silver Creek Preserve near Hailey, Idaho
provide evidence for farm practices that reduce sediment and modulate stream temperatures. At
several other locations throughout the country, TNC has documented significant positive impacts
on water quality through changes in farm practices and management. The Field To Market initiative
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Upper Snake River Basin Water Stewardship Assessment
can also play an important role both informing the efficacy of particular field management practices
and catalyzing the adoption of proven practices.
Considerable funding opportunities exist to support the implementation of farm practices that
improve water quality outcomes. Where possible, federal and state resources should be leveraged
to extend the impact of corporate stewardship investments. TNC Idaho staff have experience
connecting farmers with these resources and can help facilitate this work.
4.2.4 Protecting fish and wildlife
Aquatic fish and wildlife, including the endangered Physa snail, face significant challenges related to
water quality impairment and habitat loss. The on-field activities discussed previously, including
those being implemented at Silver Creek, have significant potential to improve water quality for fish
and wildlife.
While there is also the potential to protect instream flows through reductions in irrigation
withdrawals, it can be difficult to link such activities to specific stream reaches (Van Kirk 2013).
Mitigating instream flows through the use of on-field practices and technology should be explored
on a case-by-case basis.
4.3
CONCLUSIONS
The Upper Snake River Basin presents considerable challenges for corporate water stewardship.
Connectivity between surface and ground water adds complexity to water management and risk
mitigation. Summarized below are the key components of water risk that are expected to impact
growers over the coming decades. These risks hold important implications for companies that
source agricultural products in the region. We also outline general stewardship actions that can be
taken by companies to mitigate supply chain risks in the Upper Snake River Basin. These
recommendations are intended to guide future discussion that should capture broader perspectives
on activities and outcomes.
4.3.1 Risk summary
(1) Changes in irrigation—namely increased groundwater pumping and decreased incidental
recharge—have depleted the ESPA from peak storage levels in the 1950s. This decrease in
aquifer storage has reduced ESPA spring outflows to surface water.
(2) In years of average or below average precipitation, groundwater irrigators are at risk of
curtailment due to delivery calls from more senior spring-dependent surface water users.
(3) Water quality impairment of surface and groundwater sources is a growing concern, with
agriculture a potentially significant source of pollution.
(4) Fish and wildlife are vulnerable to water quantity and water quality impacts that result from
agricultural activities. The risk of enforced mitigation actions for aquatic species protection,
including regulatory actions, will likely increase.
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Upper Snake River Basin Water Stewardship Assessment
(5) Future climate change is expected to increase water scarcity through the combined effects of
decreased snowpack and increased consumptive crop water use.
4.3.2 Next steps
(1) Clarify objectives and resources for corporate water stewardship in the Upper Snake River
Basin relative to water risks and sustainability outcomes.
Given the scale of the aquifer storage challenge (several hundred thousand acre-feet per year),
companies engaging in water stewardship activities should first define their objectives. These
objectives will help define the range of activities that can be considered and the level of
stakeholder engagement necessary. For example, objectives could focus on basin-wide
quantitative risk mitigation targets or could support continued piloting of field-scale
interventions.
(2) Engage stakeholders to develop an action plan for corporate water stewardship in the basin.
Once stewardship objectives have been clarified, it will be important to engage with relevant
stakeholders. Some of these key groups have already been identified in this report. Identifying
other partners, including other agricultural product sourcing companies, will be a necessary
follow up activity.
(3) Coordinate with the IWRB CAMP implementation process and committee to ensure alignment
of objectives.
The Conjunctive Aquifer Management Plan (CAMP) is the primary management mechanism for
addressing water challenges in the basin. Any stewardship plan objectives and actions should
be coordinated with this established multi-stakeholder organization to ensure the avoidance of
adverse outcomes. TNC committee participation presents a possible avenue for engaging the
IWRB and CAMP process.
(4) Assess supply chain grower practices, water use, and water rights.
Prior to developing strategies for improving on-field best management practices and
technology, it is necessary to better characterize current grower practices. The prevalence of
particular practices (e.g. end gun use or alfalfa rotations) will allow for projections of mitigation
impact and enable the prioritization of the most effective implementation actions. Field to
Market offers a solid foundation for capturing this kind of information from growers, but
understanding the range of practices applied by all growers will provide a critical baseline upon
which to strategize.
(5) Prioritize on-field activities with co-benefits.
Where water stewardship objectives include the implementation of on-field activities,
implementation should be targeted to practices and locations that maximize co-benefits such as
reduced pollutant loading or increased stream flows. Developing this prioritization
methodology will require more detailed information on basin conditions.
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Upper Snake River Basin Water Stewardship Assessment
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Upper Snake River Basin Water Stewardship Assessment
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