Lake Weir Environmental Assessment
Phase 1 Data and Literature Search and Review
This report presents of summary of a literature and data review on the environmental
characteristics of Lake Weir. The purpose of this phase of the investigation is to provide
an understanding of the lake conditions and characteristics as well as the factors
influencing the health of Lake Weir.
A cursory field reconnaissance of the shoreline areas of Lake Weir, Little Lake Weir
(LLW) and the Sunset Harbor area (SSH) was performed on February 14, 2003.
Interviews were conducted with staff of the Marion County Parks and Recreation
Department, the Florida Fish and Wildlife Conservation Commission, Lake Weir
waterfront residents and other individuals with insights on Lake Weir. The most
comprehensive study of the lake to date was completed in 1992 and provided a
historical assessment of watershed and lake conditions and studied a wide range of
biological and abiologic parameters of the lake (Crisman et. al. 1992). The reader is
referred to this report for more in-depth information on the lake.
Phase 2 of this study will involve a more intensive, site specific field reconnaissance of
existing and potential recreational facility sites. The site assessments will be designed to
identify resource protection areas (RPA’s) as well as other site characteristics in order to
assist designers with the design and location of new or expanded water dependant
facilities and ancillary recreation activities.
BACKGROUND
Lake Weir is a large, somewhat circular shaped, relatively deep lake located
approximately 16 miles southeast of Ocala, Florida (See Figure 1). The rural town of
Oklawaha is located near the northern shore of the lake. The lake is located within the
Central Lakes Physiographic Division (Brooks) and the Sumter Uplands Province (White,
1970).
Lake Weir is located in a karst region of the southeastern United States. In this respect,
the area is underlain by a thick sequence of carbonates, particularly soluble limestone.
The lake is surrounded by sand hills and highly permeable sands. Therefore, drainage is
typically internal with little overland flow and creeks and streams are rare as is typical in
karst terrains. There is no direct inflow to Lake Weir other than from rainfall, surface
water drainage (runoff) within the basin and ground water flow. During high water
periods surface water would flow out of the lake into a loosely defined drainage way in
the northeastern portion of the lake to the Oklawaha River. However, in or around 1938
a weir structure was installed near this outfall which essentially raised the high water
level of the lake. According to the SJRWMD the outfall elevation is 57.4 feet NGVD.
Two aquifers are present in the Lake Weir area. The surficial aquifer exists in the
surficial sands and inter bedded clayey sand lenses. The surficial aquifer is underlain by
deeply weathered clays and clayey sands comprising the Hawthorn formation. The
highly permeable Eocene aged limestone underlying the Hawthorn Formation comprises
the Floridan Aquifer, the main drinking water source for the area. Potentiometric surface
maps of the area indicate that the elevation of the Floridan Aquifer in the area of Lake
Weir is approximately 45 feet NGVD (Rohrer, 1981), indicating that Lake Weir acts as a
recharge area to the aquifer.
1
Figure 1 Location Map Lake Weir, Marion County, Florida
The Lake Weir basin is made up of three distinct areas: Lake Weir proper; Sunset
Harbor (SH), which is located in the southwest corner of the lake; and Little Lake Weir
(LLW), which is connected to Sunset Harbor to the north via a canal. All three of these
bodies of water make up the Lake Weir lake system. According to the SJRWMD, the
Lake Weir drainage basin including lakes as shown in Figure 2 is approximately 13,650
square acres, of which almost half or 6,000 acres is surface water of lakes. Lake Weir
has a surface area of approximately 5,760 acres or 9 square miles and Little Lake Weir
has a surface area of approximately 300 acres. Therefore, the land portion of the basin
or watershed is approximately 7,590 acres.
2
3
Figure 2 Lake Weir Drainage Basin
Selected water chemistry parameters (data) as well as physical and biological
characteristics of the lake have been collected and studied on a limited basis since at
least 1956. Water quality data has been collected on a limited basis since 1968 and on a
regular basis with a standardized protocol as part of the Lake Watch Program since
1990. Water quality data combined with the physical attributes (morphometric features)
of the lake can provide valuable insight into the condition or health of a lake as well as
how stable or adaptable it is to changing conditions. Table 1 provides a summary of the
morphometric parameters of the lake.
TABLE 1
Morphometric Parameters of Lake Weir
(adapted from Brezonik and Messer 1975)
Lake Weir
Watershed Area (acres)
Lake Surface Area (acres)
Maximum Length (feet)
Maximum Width
Volume (U.S.gallons)
Maximum Depth (feet)
Mean Depth (feet)
Shoreline Development Index (DL)
Volume Development Index (DV)
Shoreline Length and Sinuousity
5760
17,390
16,405
38,750 x 106
34.1
Little Lake
Weir
300
4400 1
5600
1,400 x 106
21
Total
7,590
6060
NA
NA
40,150 x 106
20.7
1.7
1.8
Lake Weir is a large, relatively deep lake with steep sides and circular shape. A copy of
a bathymetric map produced by Florida Lakewatch is provided as Figure 3. LLW is
somewhat shallow, triangular shaped lake. Both lakes have very linear (non-sinuous)
shorelines. Shoreline Development Index (DL) is relative indication of how “circular” a
lake is and is based upon a comparison of the shoreline length to the circumference of a
circle. Lake Weir has a DL of 1.7. The smallest possible DL of 1.0 indicates a purely
circular lake. Brezonik (1975) indicates that the lakes are most likely of solution origin
and resulted in the coalescing of three sinkhole-type features as is common with many
Florida lakes.
The Fetch is the distance across the lake in any direction. Lake Weir is a very large lake
and has a fetch of approximately 3.3 miles. This large fetch allows wind driven waves to
build. Wind can influence the oxygen and heat distribution on the lake. Wind is very
important for deeper lakes, since many deeper lakes have a shallow and deep layer of
water that may be separated by a sharp temperature difference referred to as thermal
1
Maximum length and width of Little Lake Weir was determined by author from USGS Quadrangles and
GIS mapping
4
Figure 3 Bathymetric Map of Lake Weir, Sunset Harbor and Little Lake Weir
5
stratification. Since the bottom layers typically become oxygen depleted, it is important
for stratified lakes to periodically mix these layers and wind is one of the more important
influences on mixing of these layers. Studies of Lake Weir have indicated that there
appears to be no thermal or oxygen stratification and this may be due to the large fetch
and the regular influence of wind on keeping the lake waters circulating.
Lake Weir has an approximate volume of 38 billion gallons of water or 118,900 acre-feet
of water. Certainly, this large volume allows for a more stable lake in terms of water
chemistry and temperature.
The vegetated littoral zones (the band of the lake shoreline to where the rooted aquatic
vegetation ends) of lakes are one of the most important areas since they protect
shorelines from erosion, buffer wave action, provide food and shelter for aquatic
organisms, trap sediment, and absorb nutrients. The majority of Lake Weir has a
characteristically short littoral zone principally as a result of the steep sides of the lake.
Therefore, alterations to the littoral zone could have a significant impact on the health of
the lake.
WATER LEVELS
Lake water level is an extremely important lake parameter. Water level affects not only
the volume of the lake and the characteristics of the shoreline, but also play an
extremely important role in biological processes. Fluctuating lake water levels are a
necessary function of a healthy lake. High water conditions help to disperse seed
sources and allow water to periodically reach upper elevation wetland areas that are
only periodically inundated. Under these conditions nutrients and sediment can be
removed from the water and fish and other organisms can capitalize on newly available
areas to exploit for food and other resources. However, these functions are no longer
available when these wetland areas have removed or been replaced by residential lawns
and other uses. Low water levels expose shoreline vegetation, help oxidize
accumulated organic sediments and expose new areas for fish bedding and plant
propagation thereby expanding the important littoral zone.
Recreational activities can also be impacted as a result of fluctuating water levels.
Extremely high waters can cause shoreline erosion, property damage and make access
to water dependant facilities difficult. Extremely low water levels similar to thos
experienced on Lake Weir for the past few years can create access problems at (dock
and ramp) facilities, create shoaling and make navigation problematic or dangerous in
shallow areas.
Water levels on Lake Weir are recorded at a USGS gage (02238800) along the
northeastern shore of the lake (see Figures 4 & 5). Period of Record Maximum water
level on Lake Weir was recorded at 59.6 feet NGVD, in January 1938 (prior to weir). The
POR maximum (mean monthly) water level since the weir has been in place was
recorded on 59.25 feet. NGVD, in September 1960. Anecdotal information provided by
Cristman et. al. indicates that the water level was originally around 61 feet NGVD in
1883. A review of the POR data indicates that water levels on Lake Weir have been on
a severely declining trend since at least 1987 (See Figure 6).
6
Figure 4 Lake Weir Gage Location
Figure 5 Photo of Lake Weir Gage
7
Figure 6 Period of Record Water Level Lake Weir
Since there are no direct surface water inputs into the lake, then rainfall and recharge
have the most influence on water levels in the lake. In an examination of the period of
record (POR) water levels Cristman et. al. (1988) reported that since 1943, lake surface
water levels have closely reflected the previous years rainfall.
Minimum flows and levels are regulatory lake level guidance levels (40C-8 F.A.C.) and
were first established (recommended) by the SJRWMD for Lake Weir in 1997. These
levels were then reevaluated in 1999 based upon additional information and field data
(vegetation transects):
Minimum Frequent High
Minimum Average
Frequent Low
1997
57.4
56.3
55.2
1999
57.2
56.4
54.9
LAND USE / LAND COVER
Land uses and the vegetation types within the watershed are the strongest influences on
the nutrient inputs to a lake. Man-induced changes within the watershed such as land
clearing, changes in agricultural uses and practices, industrialization and urbanization
can introduce sediment laden storm water runoff, pesticides, toxins and nutrients, alter
the littoral zone and ultimately create short-and long-term alterations in the water quality
of the lake.
8
Crisman (1992) was able to develop a chronology of potential nutrient source inputs to
the lake by examining changes in the land use practices and patterns within the Lake
Weir watershed. These were supported by the sediment data referenced later in this
report. Anecdotal information indicates that the dominant land covers within the basin in
the late 1800’s were pine forest and hammock. Crisman indicated that a photograph of
the southeastern shoreline of Lake Weir from 1900 showed dense hardwood hammock
vegetation as well as cypress stumps in the littoral areas.
Major deforestation occurred in the mid to late 1880’s, creating land for pasture and
citrus groves and wood for homebuilding. Crisman estimates that over half of the land
within the watershed was cleared of its pine forest in the late 1880’s. Citrus groves
were well established by 1883, however, major freezes in 1894 and 1984 killed most of
the citrus trees, which may have released nutrients. Citrus groves appeared to peak at
4200 acres in 1964, but were reduced to approximately 170 acres of living groves after
the 1984 freeze. The amount of pastureland appeared to peak in 1957 and in 1985.
The weir structure was installed in 1938 and may have had a large influence on lake
levels, flushing of the lake as well as how
the lake responded to nutrient inputs. An
examination of early maps indicated that the
lake appeared to be connected to the
Oklawaha River at the lakes northeast
corner by a baygall (forested wetland
swamp) or intermittent stream prior to 1938.
The dominant land cover in the Lake Weir
watershed in 1975 was agricultural lands,
principally mature citrus groves estimated at
12.2 km 2 (3,000 acres) or approximately
55% of the watershed. Wetland and Forest cover each made up approximately 17% of
the watershed and approximately 7% was
urban/suburban (Brezonik, 1975).
Residential areas made up only 1% of the
watershed in 1940, however had increased by a
factor of 10 by 1985, most of which occurred after
1964 (Crisman 1992). The associated road
network (length of roads) increased by 200% in
the northeast corner of the watershed from 1970
to
1977. Dredging is another alteration
typically associated with urbanization
that can have unintended water quality
consequences. The canal between Little
Lake Weir (LLW) and Sunset Harbor
(SH) was first dredged between 1949
and 1957 and then lengthened and
widened by 1964. The canals and bridge
9
access to Bird Island were created sometime between 1957 and 1960 (Crisman 1992).
There is also some indication that sand was actually mined from the lake by the Lake
Weir Washed Sand Company.
A recent land use land cover map of the watershed (1999) based upon SJRWMD data is
provided as Figure 8.
WATER QUALITY
Selected water chemistry parameters as well as physical and biological characteristics of
the lake have been collected and studied on a limited basis since at least 1956. Water
quality data has been collected on a limited basis since 1968 and on a regular basis with
a standardized protocol as part of the Lake Watch Program since 1990. Brezonik and
Messer (1975) performed an analysis of the lake in 1975, utilizing data collected in 19691970 and 1974-1975 and Crisman et. al. (1992) provided an in-depth analysis of the lake
biotic and abiotic characteristics and the potential causes of historical eutrophication.
The later study went so far as to analyze/extrapolate historic conditions within the basin
reported in the late 1880’s (from Shackelford, 1883).
Numerous studies have indicated that water quality of Lake Weir is “GOOD”. Brezonik
and Shannon (1971), in their study of 55 central Florida Lakes, classified Lake Weir as a
clear-soft water lake based upon six basic water quality parameters (pH, Alkalinity,
acidity, conductivity, color and calcium). In addition, turbidity values from Lake Weir
were in the lowest third of the 55 lakes (Brezonik and Shannon, 1971). The lack of
hardness and low alkalinity implies that there is no direct connection with the Floridan
Aquifer and no significant spring flow into the lake. The low color values can be traced
to the lack of extensive adjacent swamps and pine flatwoods (Brezonik and Messer
1975) as well as prevalence of nutrient poor, sandy soils in the basin.
Nutrients such as phosphorous and nitrogen are important water quality parameters that
are necessary for biologic productivity. Studies indicate that Lake Weir is a
phosphorous limited lake, similar to many of Florida’s water bodies. This occurs when
the nitrogen to phosphorus concentration ratio is greater that 30. A phosphorous limited
water body is one in which
more nitrogen added to the
system
does
not
significantly increase the
primary
productivity
or
eutrophication of the lake
since nitrogen levels have
exceeded thresholds and
more than enough is
available for plant growth.
However, under this scenario, relatively small increases in phosphorous can result in
significant increases in plant productivity and create large algae blooms. It should be
noted that phosphorous is taken up or removed from the
10
FIGURE 8
11
water column in adjacent wetlands and by the aquatic macrophytes in the littoral zone
(Messer 1975, in Crisman 1992).
Sediment mixing and re-suspension can result in phosphorous being reintroduced into
the water column. This can be caused by large waves from the wind fetch as well as by
boating activity. Lake Weir’s morphometry, including its narrow littoral zone and deep
“bowl-shape” help to minimize these effects (Crisman 1992).
Bird waste can also contribute phosphorous to a lake, although in many cases this is
though to be minor. One study of 33 Florida lakes found that bird abundance and
species richness of birds correlated well with lake area (size) and total chlorophyll a. It
has been reported that significant rafts of gulls have been observed on Lake Weir.
These birds apparently fly in from the nearby landfill on a regular basis and may be a
significant source of phosphorus and ultimately result in increased chlorophyll a
concentrations in the water column.
Lake Weir was originally on the State of Florida’s Impaired Waterbody (“303(d)”)
planning list for zinc, copper, lead and silver. It is important to note that, these potential
parameters of concern (with the exception of copper) did not make the final “verified list”
sent to the U.S. EPA, most likely because these parameters showed up as isolated
incidents in water quality sampling and therefore did not meet the statistical
(repeatability) requirements for final listing.
However, nutrients (Trophic State Index) were listed as a parameter of concern for Lake
Weir and Lake Weir outlet and copper was listed as a parameter of concern for Lake
Weir on the final verified list2. These parameters were listed as a medium priority and
2007 is the target year for developing TMDL standards (Total Maximum Daily Loads),
which would include public hearings by FDEP as they develop standards.
It should be noted that copper was added to the verified list for Lake Weir because the
standards (EPA acute thresholds) were exceeded in 2 out of 21 samples in the past 7.5
years. These occurred in 1996 and 1997 with no exceedances in 1995 and 1997.
Furthermore, no samples have been collected since 1998.
The following criteria are listed by EPA as the nutrient standards (items b and c apply to
Lake Weir because of its color):
“Lakes or lake segments will be listed for nutrients if:
a) for lakes with a mean color greater than 40 platinum cobalt units, the annual
mean TSI for the lake exceeds 60, unless paleolimnological information indicates
the lake was naturally greater than 60, or
b) for lakes with a mean color less than or equal to 40 platinum cobalt units, the
annual mean TSI for the lake exceeds 40, unless paleolimnological information
indicates the lake was naturally greater than 40, or
c) for any lake, data indicate that annual mean TSIs have increased over the
assessment period, as indicated by a positive slope in the means plotted versus
time, or the annual mean TSI has increased by more than 10 units over historical
values."1
2
USEPA 2003. “DECISION DOCUMENT REGARDING DEPARTMENT OF ENVIRONMENTAL PROTECTION’S
§303(d) LIST AMENDMENT SUBMITTED ON OCTOBER 1, 2002 AND SUBSEQUENTLY AMENDED ON MAY 12,
2003”. Prepared by the Environmental Protection Agency, Region 4 Water Management Division June 11, 2003.
(http://www.epa.gov/region4/water/tmdl/florida/florida303d_update.pdf)
12
Eutrophication and Trophic State
Eutrophication is a natural process that describes a lakes nutrient enrichment, increasing
lake productivity and general lake aging (Addy, K. 1996). In general, “eutrophication is a
result of excessive nutrient and organic input to a lake and is characterized by increases
in phytoplankton biomass, macrophyte biomass, nuisance algae blooms, loss of water
clarity from increased primary
production, and loss of oxygen
in bottom waters” (US EPA).
The trophic state of a water
body is a reference to its
biological productivity, and is
based principally upon its
nutrient levels or relative nutrient
enrichment, sometimes referred
to as its relative eutrophication.
Climatic,
hydrologic
and
morphologic
factors
also
influence trophic state. At one
extreme, a remarkably clear, low
nutrient poor lake, that maintains
a high dissolved oxygen content
is in a trophic state of
oligotrophy or referred to as an
oligotrophic lake (or ultraoligotrophic).
At the other
extreme, a lake rich in nutrients,
with a high biologic productivity
with much species diversity, sometimes characterized by high algal content is referred to
as a eutrophic lake 3. A lake where the nutrient levels are so extreme as to have virtually
continuous algal blooms, depleted oxygen content, and a resultant low diversity of
species that can endure these extreme conditions is termed hyper-eutrophic.
Mesotrophic lakes are those where conditions fall in between oligotrophic and eutrophic.
A lake whose trophic state appears to be out of character or out of sync with its
watershed may be termed dystrophic. Many ponds and lakes are naturally eutrophic.
Source: Florida Lake Watch
Cultural eutrophication is typically used to described the response to accelerated input of
nutrients and organic material resulting from human activities in lakes and their
watersheds, over and above what the lake can naturally/normally process. From a
human perspective, eutrophication problems might include loss of aesthetic appeal,
decreases in desirable gamefish, loss of accessibility due to increased macrophyte
production, and increased cost of treating drinking water.
Based upon a paleolimnological assessment of the lake sediments Crisman (1992)
indicated that the lake appears to originally have been an oligotrophic lake.
However, since at least 1970, Lake Weir has been in a mesotrophic state. That
study also indicated that three primary watershed events adversely impacted past
3
Eutrophic is of greek derivation meaning “well fed”
13
trophic state. These included: land clearing in the basin in the late 1800’s,
installation of the weir in 1938 and expanded human settlement following World
War II. Furthermore, he indicated that the lake appeared to return to baseline
conditions within 20-30 years after the first event, but this trend was not evident
after the other two, more recent periods.
According to Crisman (1992) the largest threat to cultural eutrophication of Lake
Weir is nutrient enrichment from
expanding human population,
particularly from storm water
runoff and septic systems. Vacant
and agricultural lands also may be
a significant contributor.
In Florida, two common rating
methods have been used to describe
or rate lake conditon or relative
ecological health. The Trophic State
Index (TSI) is based primarily on
water quality parameters and the
Lake Condition Index (LCI) adds a biotic component by including macroinvertetebrate
diversity along with the water quality (nutrient) parameters.
Trophic State Index
The Trophic State Index (TSI) was developed as a method of classifying a lake based
upon the lake’s chlorophyll concentration, Secchi depth (a measure of the water clarity)
total nitrogen and total phosphorus concentrations (FDER 1990). It is a modification of a
trophic classification system originally developed in 1977 (R.E.Carlson). It was originally
envisioned that a change of 10 units in the index would represent a doubling or halving
of algal biomass represented in the lake system. Regression analysis of data from 313
Florida Lakes were used to develop the indices for Florida Lakes and resulted in the
following values:
TSI
Good 0-59
Fair 60-69
Poor 70-100
According to FDEP the desirable upper limit (of the good classification) for the index is
set at 20 ug/l chlorophyll, which corresponds to a TSI index of 60. Doubling the
chlorophyll concentration to 40 ug/l results in an index increase to 70, which is the lower
limit for undesirable (poor) lake quality. Many authors caution in the association of water
quality descriptors with trophic state.
In order to determine the TSI the individual parameter TSI’s must first be determined.
Simplified version utilizing three components of total phosphorus (ug/l), Secchi depth
(meters) and Chlorophyll a (µg/l) as described in Carlson (1977) is
TSI SD = 60-14.41x ln(SD)
TSI Chla = 9.81 x ln(Chla) + 30.6
14
TSI TP = 14.42 x ln(TP) + 4.15
Where:
CHLA is Chlorophyll A concentration in µg/l; SD is Secchi Disk depth in meters; TP is Total Phosphorus in
mg/l, and ln is natural log;
A trophic state index has been developed for Florida Lakes (Brezonik and Shannon
1971) that was based upon a scale of 1-10. Lake Weir was included in that 1971 study
of 55 Florida lakes used to develop the index as detailed below. The TSI for Lake Weir
was calculated to be in the lower end of the Mesotrophic Range (3.3).
Hyper-eutrophic
Eutrophic
Mesotrophic
Oligotrophic
>10
7-10
3-7
2-3
The formula Brezonik and Shannon used for clear lakes like Lake Weir was:
TSI= [0.936(1/SD) + 0.827 (COND) + .907(TN) + 0.748 (TP) + 0.938 (TP) + 0.892 (CHLa) + 0.579(1/CR)] + 4.76
Where:
TSI = Tropic State Index, SD = Secchi Depth; COND= Conductivity; TN= Total Nitrogen; TP= Total
Phosphorous; CHLa = Chlorophyll a; CR = cation ratio
A review of the above-referenced reports and data collected by Lake Watch at Lake
Weir indicate that the TSI for the lake has been consistently in the upper end of the
Oligotrophic Range or the lower
end of the Mesotrophic Range or
an Oligo-Meso Trophic Lake .
Crisman (1992) indicated that
historical TSI for TP and Secchi
were lower than present and
historical TSI for CHLa and TKN
were higher than present.
Brezonik and Shannon (1971) in
their study of 55 Florida Lakes,
found that most eutrophic lakes
were shallow (had mean depths of
4m or less) and oligotrophic lakes
within the study groups were
deeper. Therefore, with a maximum depth of over 34 feet and a mean depth of over 20
feet, depth may be the largest factor controlling the trophic state of Lake Weir and may
account for the relative trophic stability of the lake.
Figure 6.1 Graphical Representation of Trophic State Index.
Source: http://lakeaccess.org/lakedata/datainfotsi.html
Several modifications or iterations of the TSI have been suggested by various authors. A
number of those modifications incorporate an assessment of the standing biomass of
aquatic macrophytes or percent volume of the lake infested (PVI) by aquatic
macrophytes. This biomass TSI was developed based upon the observation that there
15
are noted differences in the trophic condition of lakes that have a relatively large
biomass of aquatic plants from those that are dominated by phytoplankton and do not
necessarily have a large aquatic macrophyte infestation. Lakes with a large PVI typically
can assimilate nutrients more effectively and have more nutrients tied up in the aquatic
macrophyte biomass.
Lake Watch for Lake Weir reported percent area coverage of 26% (which seems
unusually high considering the large lake area) and a PVI of only 1.5% and a 44% PAC
and 3.5% PVI for Sunset Harbor (Lake Watch, June 25, 1992). A review of aerial photos
1940, 1957 and 1964 showed extent of aquatic macrophytes similar to modern times.
Water bodies such as Lake Weir that do not have a large PVI are either nutrient poor
(oligotrophic) and/or the nutrients are assimilated by the phytoplankton or algal
component and may exhibit a relatively higher chlorophyll a concentration as a result.
Therefore, the CHLa TSI for Lake Weir may not accurately reflect the trophic state.
Lake Condition Index
The Lake Condition Index (LCI) was more recently developed as a lake bio assessment
protocol to assess and monitor the ecological condition of Florida lakes (Gerritsen, J. et
al. 2000). LCI is based upon a more detailed analysis of lake conditions than the TSI
and combines the scores assigned for total phosphorous, total nitrogen, chlorophyll a,
macroinvertebrates present, and diversity of mactoinvertebrate community taxa.
That report, which included an assessment of 122 reference (base line, non-stressed)
and 84 non-reference (stressed) lakes within 36 lake regions of Florida, revealed the
lakes can be classified based upon geographic region, water chemistry and biological
(macroinvertebrate) species composition. Based upon these criteria the lakes were
divided into the following groups: acid-clear, acid-colored, alkaline-clear, and alkalinecolored. In addition, the report indicated that “benthic macroinvertebrate species
composition is most strongly affected by lake water color, and somewhat less by water
pH and the geographic ecoregion of the lake” (Gerritsen, J. et al. 2000).
The LCI for an individual lake is used to compare with the values or threshold of other
reference lakes within the same group (class) of lakes. The FDEP report (Gerritsen, J.
et al. 2000) recommends utilizing a chlorophyll-Secchi trophic index for colored lakes
and a specific benthic macroinvertebrate index for clear lakes (water color < 20 PCU) for
discriminating unimpaired reference lakes from stressed lakes. Lake Weir is
considered a clear (non-colored) lake, therefore, the benthic macroinvertebrate
index (categorical, using 95% metric scoring) should be used for the LCI. The
reader is referred to this report for more information on the assessment
methodology.
Benthic macroinvertebrates at Lake Weir were sampled by Crisman (1998) at seven
profundal stations (areas lacking rooted aquatic vegetation) monthly for a year. Two
community structures emerged: an amphipod dominated group and an insect dominated
group. Oligochaetes (bottom feeding worms) were relatively scarce indicating GOOD
Water Quality (Crisman et. al 1988). While Crisman did not use the LCI, he did suggest
that the mayfly Hexagenia, which was present in Lake Weir in considerable numbers,
might be used as a water quality indicator species, since it is sensitive to low dissolved
oxygen (DO) content. Maintaining dissolved oxygen content is a key component to a
16
healthy lake biota and a low DO would significantly reduce the population or reportedly
devastate this species. The data indicated that this macroinvertebrate was most
abundant at Little Lake Weir, Sunset Harbor and the southern shore of Lake Weir.
A paleolimnologic study of the extremely eutrophic Lake Apopka (Shumate, et. al. 2002)
revealed that the cladoceran community of macroinvertebrates appeared to change in
the sediment profile, just below a sediment discontinuity layer (SDL) associated with a
shift in the trophic state of the lake in the late 1940’s. Based upon this information,
monitoring the cladoceran community profile may be useful in predicting early changes
in trophic state on Lake Weir. However, it should be noted that there are many
differences between Lakes Weir and Apopka. Lake Weir is a large deep lake and Lake
Apopka is a large, but relatively shallow, polymictic lake. Even so, it has been strongly
suggested “that increased trophic state may manifest itself as changes in the benthic
assembledge before it is detectable as increased chlorophyll or reduced (secchi)
transparency” on clear, non colored lakes such as Lake Weir (Gerritsen, J. et al. 2000).
The methodology for determining the LCI is too detailed to elaborate in this document
and the reader is referred to the study for more information (Gerritsen, J. et al. 2000).
However, it is important to note that the LCI study proposed the following thresholds for
Benthic LCI in clear lakes (in Ecoregion 75 – Southeast Coastal Plain):
Very Good
Good
Poor
Very Poor
Clear Acid
44
30
15
<15
Alkaline clear
50
35
18
<18
FISH
Recreational fishing and maintaining a healthy fish population as part of the food web is
important on Lake Weir. Studies indicate that Lake Weir has a normal assemblage of
fish for the size of lake, trophic state and pH range (Crisman 1992). Fish reported by
FFWCC present in Lake Weir in 1985 included largemouth bass, various sunfish, black
crappie, bullheads and threadfin shad among others. The latter is an important prey fish
for game fish. In general, fish production is closely linked to phytoplankton which are at
the base of the food web (Ryder et al. 1974). Increased eutrophication from nutrient and
organic inputs generally results in increases in phytoplankton biomass which can be
helpful to fish population up to a certain level. Excessive nutrient input and
phytoplantkon response can have a detrimental effect on fish populations by producing
nuisance algae blooms, a resultant loss of water clarity from the increased primary
production, and an increased oxygen demand which can result in oxygen depletion in
the water column.
The lake experienced a major crappie die-off between 1982 and 1984. Researchers
have studied many potential factors but are still unsure of the cause and have indicated
that the populations have not returned to previous levels.
Angler surveys and fish creel studies revealed that fishing on Lake Weir, in terms of
angler effort and success is pretty much near the Florida and national average of
17
approximately 4 hours per trip (Sam McKinney, FFWCC personal communic ation
3/24/03). He also indicated that night fishing is a frequent activity on Lake Weir and
should be considered in any boat ramp or recreational facility design.
SEDIMENT
The substrate of Lake Weir was originally sand but now as much as a meter of flocculent
organic material has accumulated on the bottom (Crisman 1992). Analysis of cores
taken from the north shore of Lake Weir indicated a uniform accumulation rate of
approximately 0.017 g/cm2/year from approximately 1780 to 1938 (utilizing Isotopic
Lead 210 analysis). Accumulation rates almost doubled after the weir was installed
(1938). Accumulation rates varied but exhibited a general increase over the historic rate
from 1939 until 1946. A sweeping decline in accumulation rates was observed by
Crisman from 1947-1980, then increasing slightly after 1980. Crisman also found
increasing phosphorous levels in the core in
recent times, including an apparent doubling
in 1938, again associated with the weir
installation. Other studies indicate that there
is little evidence to indicate that cultural
factors have played an important influence
on the chemical composition of the lake
(Brezonik and Messer 1975). He concluded
however, that accumulation was more
closely related to human population than to
watershed land use (Crisman 1992).
That study also analyzed pollen, algae and nutrients within the sediment cores. Pine
pollen exhibited good correlation in the cores and reflected an abundance of pine forest
in the watershed prior to 1900 and a decreasing trend from 1900 to 1980. Recent small
increases in the past three decades were most likely due to replanting or conversion of
citrus to pine in response to freeze losses. Algal species exhibited four distinct periods
within the core that were associated with changes in the watershed. These included
elevated algal core abundance associated with major land clearing within the basin
around 1900, the installation of the weir in 1938, and rapid population growth associated
with high TP in 1987. A brief period of low algal abundance as well as a shift in species
dominance was associated with 1980, and was thought to be associated with high water
levels.
CONCLUSIONS
Overall, Lake Weir can be classified as an Oligo-mesotrophic lake with generally good
water quality. The lake is considered a deep, clear (non-colored), soft-water lake. The
Lake was most likely historically an Oligotrophic lake but has more recently moved into
the lower range of mesotrophy. Nutrient analysis indicates that the lake is a
phosphorous limited lake indicating that small inputs of phosphorous can have dramatic
changes in the nutrient response. The biotic components, particularly the
macroinvertebrate profile appear to be representative of good water quality. However, a
review of land use changes in combination with the sediment profile and historic water
quality data indicate that the lake is sensitive to changes within the watershed, and has
responded somewhat negatively to land clearing and urbanization. These negative
responses include: increase in occurrence or severity of algae blooms, reduced water
clarity, reduction in the macroinvertebrate diversity or alterations in the ratio of the
18
favorable vs. unfavorable macroinvertebrates.
It is suspected that the Lake has
rebounded after many historic land use change events and remained in the oligomesotrophic range primarily due to the morphologic characteristics, particularly its depth
and water volume and in part due to the vegetated littoral fringe. Increases in population
/ urbanization of the water shed and particularly the lake edge threaten to reduce or alter
the littoral zone vegetation, increase nutrient inputs from storm water runoff, fertilizers
and septic systems. Aquatic macrophytes in the littoral zone act as a buffer between the
land and open water of the lake and intercept and trap sediments, stabilize shoreline and
offer protection from erosion, provide habitat and shelter for aquatic animals and uptake
and process nutrients. The littoral fringe on Lake Weir is narrow in most areas of the
lake.
Cristman (1992) indicated that “Given the fragile nature of the vegetated littoral
zone in Lake Weir, increased boating activities associated with expanded
population could have a marked negative impact on the lake”. He further
indicates that management practices should be implemented which protect this
“vegetated nearshore fringe”. It was recommended that: septic systems be
replaced with a centralized sewer system; vegetated shorelines be protected by
“no wake zones”; residents should be prohibited from altering or removing littoral
zone plants; docks other water dependent structures should be limited in size,
number and density, and; vegetated swales and retention ponds should be
incorporated for intercepting agricultural and residential run off. Furthermore, that
these policies should be implemented as part of a comprehensive watershed
management for the lake.
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Carney Island Recreation Area
Resource Protection Area Assessment
A cursory boat-based inspection of the overall shoreline of Lake Weir, Little Lake Weir and Sunset Harbor
with emphasis on county facilities (Hope Ramp, Carney Island and Hampton Beach Park) was performed
on February 14, 2003 with representatives from the Marion County Parks and Recreation and an aerial flyover of the lake was performed on February 14, 2003. A preliminary, limited scope land and water based
Resource Protection Area (RPA) Assessment was performed at the Carney Island Recreation Area in May
2003 in order to assist planners with site suitability for locating recreational based facilities. The results of
that assessment are detailed in this section of the report. This RPA assessment and this report is intended to
provide preliminary information for park planning-related siting of facilities and is not intended to replace
or be used for site specific detailed design and permitting of facilities.
Water-based RPA assessments are generally used to locate and identify significant benthic, aquatic or
submerged resource areas in need of protection. These assessments are an important of component of site
planning and permitting for water dependant structures proposed on Sovereignty Submerged Lands
(SSL’s). The results of the assessments typically are scrutinized by the pertinent regulatory agencies
during the permit application review process and are used to potentially avoid, or mitigate for potential
impacts to important RPA’s.
Water-based Resource Protection Areas (RPA’s) are generally defined as live “corals; marine grassbeds;
mangrove swamps; salt-water marsh; live oyster bars; archaeological and historical sites; endangered or
threatened species habitat; and, colonial water bird nesting sites.” (Chapter 18-21.003 (54) F.A.C.). In
accordance with the Sovereignty Submerged Lands (SSL) Management policies of the State of Florida
found in Chapter 18-21 Florida Administrative Code (F.A.C) activities on SSL shall be designed to
minimize or eliminate adverse impacts and shall not result in significant adverse impacts to SSL and
associated resources. Furthermore, activities resulting in significant adverse impact shall not be approved
unless there is no reasonable alternative and adequate mitigation is proposed (Chapter 18-21.004(2)(6) and
21.004(2)(i) F.A.C.).
For the purposes of this study, land-based RPA’s would be considered natural, native or sensitive habitats
such as the xeric sandhill vegetative community or wetlands, or those habitats that support listed
(Endangered, Threatened or Species of Special Concern) plants or animal or have a high likelihood to
support these species.
Water-Based
Water-based RPA’s are classified in a hierarchical method primarily on their relative ecological importance
and are primarily designed to categorize marine-based resources:
RPA 1 “…have resources of the highest quality and condition for that area. These resources may include,
but are not limited to corals; marine grassbeds; mangrove swamps; salt-water marsh; oyster bars;
archaeological and historical sites; endangered or threatened species habitat; and, colonial water bird
nesting sites.” Chapter 18-21.003 (54) F.A.C.
RPA 2 are resource areas “…in transition with either declining resource protection area 1 resources or new
pioneering resources within resource protection area 3.” Chapter 18-21.003 (55) F.A.C., and
RPA 3 “… are characterized by the absence of any significant natural resource attributes Chapter 1821.003 (56) F.A.C
The highest level of protection is generally afforded to mangroves, seagrass beds and live coral. In the case
of lakes, rivers and other fresh water resources level of protection is generally associated with littoral zones
20
(near shore areas characterized by erect, floating-leaved or emergent aquatic vegetation), areas of desirable
submerged aquatic vegetation (SAV) such as fresh water grass beds (species such as tape grass –
Vallisneria americana and strap-leaf sagittaria - Sagittariaa kurziana) and areas that support listed species.
Littoral zones and fresh water grass beds are extremely valuable, unique and productive ecosystems that are
intrinsically linked to the aquatic food web. Littoral zones and SAV provide important functions including:
protecting the shoreline from erosion; maintaining water quality by trapping sediments, and processing
nutrients; holding and stabilizing sediments; and serving as food, shelter and critical nursery areas for
juvenile fish and invertebrates including commercially important species as well as endangered and
threatened species. A study of Lake Weir indicated that the vegetated littoral zone is essential to the
well being of the lake and suggested that management practices should be implemented which
protect this fragile vegetated nearshore fringe (Cristman 1992).
The water based RPA assessment was conducted by performing a shallow draft watercraft survey of the
entire shoreline and diver snorkel surveys at selected areas of the near shore area around Carney Island
Recreational Area (CIRA). A key objective of the water-based field survey was to identify and locate any
RPA 1 as well as evaluate the shoreline areas characteristics necessary for locating water dependant
facilities such as piers, docks and boat ramps proposed for CIRA. The characteristics evaluated included as
presence or absence of littoral vegetation, evidence of previous disturbance, substrate type, relative slope
and depth (adequate for boat ramps and watercraft mooring)
RESULTS
Results of the water-based assessment revealed consistent shoreline conditions over the majority of the
Carney Island Recreation Area eastern shore (shore that faces Lake Weir). In this respect, the majority of
the eastern shore was characterized by a shallow
sloping bottom, typically not reaching depths of
6 feet until approximately 100 feet from shore.
A parallel band of emergent aquatic vegetation
comprising the littoral zone dominated the
shoreline area. Interspersed within the littoral
zones are small areas where the emergent
vegetation is absent and the area is dominated by
shallow open water with a sand bottom (beach
flats).
Moccasin Beach is long stretch of
shallow beach flats along the southeastern shore
where boaters, water skiers and jet skiers
congregate, anchor and picnic. It was observed
during this field reconnaissance that a large
portion of Moccasin Beach was returning to
emergent littoral zone, perhaps in part due the return of normal water levels on Lake Weir. The littoral
zone along the eastern shore was dominated by bullrush (Scirpus sp.), maidencane (Panicum hemitomon)
spikerush (Eleocharis sp.) and buttonbush (Cephalanthus occidentalis). Overall, a snorkel survey revealed
no significant grass beds anywhere along the eastern shore.
Substrate material along the eastern shore was principally fine sand with minor organic concretions
periodically encountered where wetlands were located along the shore. Fresh water clams were noted to be
very prevalent in the littoral zone and
extending lakeward of this zone. The
density of clams was significant and more
than this author has observed in anywhere
else in Florida
Apple snail (Pomacea paludosa), eggs were
noted on the emergent vegetation. The apple
snail a very important resource for the lake
21
because it feeds primarily on peryiphyton, thereby removing algae and other detrital plant matter from the
water. Apple snails and their eggs also provide an important food source for fish, turtles and alligators as
well as wading birds such as the limpkin and white
ibis
Overall, two areas along the eastern shore
exhibited evidence of previous impacts or were
identified as areas where the littoral vegetation was
sparse or absent. In order to reduce future impacts
to the littoral zones it is advisable to locate water
dependent facilities in these areas. These areas
included a site where a reported irrigation line had
run down to the lake. This area is identified from
the water by remnant wooden supports for the
irrigation pipe and a “gap” in the littoral vegetation
and from an aerial photo by two concentric sandy white disturbance “rings”.
The second area is in and around the old Coke Plant citrus loading dock. Remnant pilings are located in this
area and a gap in the littoral zone is located immediately south. However, neither of these sites provide
steep enough slopes or deep enough water at present near the shore for a boat ramp or dock without
modifications or (in the latter case),
extending out the structure to reach
sufficiently deep water. Such modification
might include dredging to create slopes
necessary for boat access.
The only submerged vegetation noted along
the eastern shore included some minor
amounts of Brazillian elodea (Egeria densa)
and Illinois pondweed (Potamogeton
illinoensis).
The elodea is a naturalized
sometimes nuisance submerged aquatic and
would not be considered an RPA 1 or 2.
Pondweed, if it was found in significant
quantities or beds would be considered an
RPA 1 or 2.
The northern portion of the western shoreline of CIRA faces Little Lake Weir and the southern portion of
the western shoreline is defined by a navigational canal connecting Little Lake Weir with Sunset Harbor.
The existing beach area is located in this
area. The areas adjacent to the beach were
evaluated for potential future expansion of
the beach. The substrate in the area was
mostly sand, with slightly more organics
that the Lake Weir shoreline.
The characteristics of the canal are similar
to other fresh water canals in Florida: the
substrate consists of detrital muck and
floating leaved and emergent aquatic
plants. Single family residential homes
and canal with seawalls, rip rap and
retaining walls are present along a large
portion of the opposite (western) edge of
the canal.
22
The southern shore of CIRA faces Sunset Harbor. The westernmost portion of this shoreline is
characterized by a combination of floating leaved and emergent aquatic vegetation, similar to that found in
the canal and described above. The eastern portion makes a transition to more emergent aquatic vegetation
and less floating leaved aquatics. Substrate characteristics include an organic (muck) surface from a few
inches to a few feet deep along the majority of the shoreline and littoral zone. Again, the near shoreline /
littoral areas were shallow. There were no areas along the southern shore or western shore fronting the
canal that are favorable for facility development due principally to the presence of wetlands, lack of sizable
adjacent uplands as well as other site conditions.
An evaluation of the area to the west of (behind) Lemon Point revealed very steep submerged slopes
Apparently this area is the site of a submerged deep feature (deep
hole) which may represent the location of a submerged sinkhole or
deep (former) spring feature. The organic mucks in the area and
lack of water clarity would suggest that the feature, if a spring,
may no longer be active. The Lemon Point area does have
adjacent upland areas, and because of the steep slope does appear
to be favorable for boat ramp development. In fact it was the only
area identified along the shoreline where depths were sufficient to
support a boat ramp with little modification. However vehicular
access to the southern portion of the site would be problematic
(see below) and the “point” area appears to be too restrictive to
site appropriate turn around areas for de boating. In addition, if
this area is indeed a sinkhole, the slopes and depths may be too
excessive for a ramp.
Land Based.
The land based assessment and review of the associated land use
land cover maps revealed that the CIRA can be divided into a
northern portion that is dominated by uplands and a southern
portion that is dominated by wetlands with “islands” of upland
areas connected by a trail system.
Northern CIRA
A review of the 1999 Land Use / Land Cover (LU/LC) data provided by the SJRWMD indicates that the
dominant land cover in the northern portion of the site includes: abandoned tree crops, fallow crops, upland
mixed (hardwood/coniferous) forest and citrus
groves, comprising just over 200 acres. The RPA
assessment revealed that citrus groves are no longer
present on the CIRA and many of these areas have
been converted to planted pines and as such do not
represent native or sensitive habitats and provide
little, if any, habitat for listed species. Interspersed
within the planted pine areas are some minor areas of
mixed
23
24
upland hardwoods, minor fallow field areas and remnant citrus trees under the planted pine canopy. A few
gopher tortoise burrows and one active tortoise (a species of special concern) was noted in the northern
portion of the CIRA. However, it appears that they are sporadically distributed, limited principally to the
more xeric, fallow field portions of the site and of a relatively low density.
The northeastern -most parcel, comprising approximately 40 acres, is labeled as citrus groves by the 1999
SJRWMD LU/LC map and was predominantly planted pine at the time of the assessment. The extreme
northwestern portion of CIRA comprising approximately 40 acres as well as a (100 foot wide) strip of land
along the northeastern shore is correctly labeled as upland mixed (hardwood/coniferous) forest. The
northwestern tract was not field reviewed during this assessment since no intensive use or facilities were
proposed. However, a review of aerial photos reveals that this may be one of the few larger remaining
tracts of in-tact mixed forest in the general area
and therefore may be a unique ecological parcel.
The upland “near shore” areas within
approximately 100 feet from the Lake Weir
(eastern) shore are dominated by upland mesic
forest with large diameter trees including
southern live oak, hickory and southern
magnolia with frequent sabal palms, providing a
esthetically pleasing tropical character.
Topographically, these near shore forested areas
are characterized by a very steeply sloped scarp,
in some cases they are near vertical. This steep
near shore area is present along the northeastern
shoreline and well as the southeastern shoreline to the north and south of Moccasin Beach. The trees and
other vegetation provide stability to the slope and prevent erosion. The steep slope presents design
challenges to the construction of water-dependent facilities or other potential proposed structures
contemplated to start in the higher upland and access the shore, particularly their ability to meet the
American with Disabilities Act (ADA) design requirements. In this respect, such structures would require
long switchback ramps and platforms or be significantly cut into the banks to meet ADA requirements.
Stairs could be used in these slope restrictive areas if alternative locations for ADA compliant facilities
could be provided. Either of the designs would require stabilization of the slope areas to insure stability and
prevent erosion.
The RPA assessment identified two areas within these
slope-restrictive shorelines where there were previous
trails, prior impacts or existing cuts in the slope and might
provide the best location for access from the upland to the
Lake Weir shoreline. These areas would be more
favorable for boardwalk access sitting due to the lesser
slope or previous impacts. One such area is located in the
northeastern most parcel and is located at a site where a
reported irrigation line had run down to the lake. This area
is identified from the water by remnant wooden supports
for the irrigation pipe and a “gap” in the littoral vegetation
and from an aerial photo by two concentric sandy white
disturbance “rings”. The second area is located near the
southern end of Moccasin Beach. At this location a more
gently sloping foot trail leads from a rest shelter at the top
of the “bluff” down to the sandy shoreline.
A wetland area and pond (sometimes) referred to as Lake
Weir Pond is located in the adjacent out parcel. This pond
25
has a forested fringe and appeared to have been used for a water source for irrigation of the adjacent citrus
groves. As such much of the ecotonal edge appeared disturbed at the time of the RPAA and exotic or
nuisance vegetation such as primrose willow (Ludwigia peruviana) and paper mulberry
(Broussonetia papyrifera) were noted around the pond. A high water pop-off was present at the
southeastern end of the pond, where during high water events, water flows overland for a short distance and
then into a depresional “swale” area. This swale area runs south onto the CIRA, appears as a forested
wetland on the LULC Map and terminates just north of the former Coke plant and the existing day use
drainage retention area (DRA) with no apparent outlet. (It is not known if a connection to Lake Weir exists
off-site to the north).
This area was scrutinized during the land-based RPA assessment since the boat ramp and associated
parking facilities are proposed to be located in this generally area of the existing day use and DRA and
northward. This purported wetland area was extremely dry with little if no evidence of hydric soils or
hydrologic indicators at the time of the assessment. An elevated road bed lies along the eastern edge of the
“wetland swale”, therefore this area did not appear to connect to Lake Weir at this location (on site).
Evidence indicates that this area on-site only received water periodically during extreme high water events
and may act as an overflow area for Lake Weir Pond and therefore may not be a jurisdictional wetland.
However, it is recommended that a juris dictional determination be performed to resolve this issue prior to
final facility design.
Southern CIRA
The southern portion of CIRA is dominated by wetland forest, shrub and marsh communities. A series of
upland islands linked by narrow walking trails through the wetland areas. These trails were most likely
historically used to maintain the citrus groves on the upland islands. Similar to northern portion of the
CIRA the southern “upland islands” were previously citrus groves and evidence of citrus trees are still
present. However, unlike the northern “converted groves” the southern groves have not been as completely
converted to planted pines, but have either become fallow forest, fallow fields, or are currently mixed
upland forest. It is estimated, based upon the 1999 SJRWMD Land Use Land Cover Map, that there are
approximately 320 acres of wetland in the southern portion of the site.
High intensity use or development of the southern portions of the site would most likely require that the
trails be expanded to accommodate vehicular traffic. Since these narrow trails cross through wetland areas,
then such expansion or access would result in wetland impacts and require that the associated
Environmental Resource Permits (ERP) be obtained and wetland impacts mitigated. For these reasons,
sitting boat ramps and higher intensity use facilities in the southern portion of the CIRA were dismissed as
impracticable
It was noted that there is an extensive but incomplete
ditch (and adjacent spoil berm) located in the
wetlands in the southwestern portion of the CIRA.
This feature may have been used for irrigation or
started as a potential navigation canal but never
completed and appeared to “dead end” at or be
blocked by the island trails or ditch blocks. It appears
that this ditch and berm may have hydrologically
altered or isolated some of the wetlands in the
southern portion of the site. A cursory assessment
revealed that the altered wetlands appear to be drier
and shrubbier, being invaded by more facultative
upland species and appear to be inundated only
during extremely high water levels on Lake Weir.
Installing culverts under the trails at the ditch and removing ditch blocks and the berm could potentially
provide an opportunity to restore hydrologic exchange to these wetlands. These wetland areas would then
have the opportunity to provide more area to provide important wetland functions such as trapping
26
sediment and taking up nutrients.
This scenario may be employed to compensate for wetland related
impacts encountered or contemplated on-site (such as for the boat ramp parking area or to later enhance
access to the southern portion of the site). Alternatively, it may be possible to fund the hydrologic
restoration of the Carney Island southern wetlands by the creation of a regional wetland mitigation bank.
CONCLUSIONS
No significant submerged Resource Protection Areas were identified as a result of this assessment. The
littoral fringe of the shore Lake Weir along Carney Island was identified as an important RPA because of
the environmental and water quality functions associated with the littoral zone. Increased value and
importance should be associated with the littoral zone at Carney Island because of the relatively small
surface area or percentage of the total lake surface area occupied by littoral zones. Additionally, shorelines
in the other residential and agricultural areas of the lake are more at risk due to development pressures and
potential shoreline alterations.
Furthermore, this assessment revealed that there are no ideal areas along the eastern shore of Carney Island
on Lake Weir to locate ramps and docks due principally to the shallow sloping shoreline. Ramps and dock
will require engineering design that may call for dredging in order to make these facilities permittable. In
order to reduce the impact to the littoral zones this assessment did identify two areas where prior
disturbance within the littoral zones are present and suggests that these areas be used for such facilities.
In order to mitigate for impacts in these areas it is suggested that the remaining vegetated littoral fringe
along Carney Island be protected from future perturbation. One such method would be to place PVC signs,
buoys or other barriers making these no entry areas. Providing mooring facilities at one or two select areas
should also redirect boat traffic and mooring away from sensitive shorelines. An additional method would
be to provide floating deck moorings for personal watercraft (jet skis) in the “facility” area, so that they do
not enter or pass through the littoral zone to reach the shore.
27