Bass Lake RehabilitationBass Lake Rehabilitation District Summer Intern Report . Prepared by: Nicole...
Transcript of Bass Lake RehabilitationBass Lake Rehabilitation District Summer Intern Report . Prepared by: Nicole...
Bass Lake Rehabilitation District Summer Intern Report
Prepared by:
Nicole Gabriel
University- Wisconsin River Falls Intern
August 2007
Table of Contents Abstract……………………………………………………………….1
Purpose………………………………………………………………..1
Background……………………………………………………………2
Introduction…………………………………………………...2
Geology of Bass Lake and the surrounding watershed……….3
Topography…………………………………………………...3
Soils…………………………………………………………...3
Groundwater Hydrogeology…………………………………..7
Aquatic Vegetation……………………………………………9
Bass Lake Fish ………………………………………………..9
Population…………………………………………………….10
Development………………………………………………….11
Shoreland Zoning in St. Croix County………………………..11
Recreational Use………………………………………………11
Sampling………………………………………………………………13
Sampled Parameters…………………………………………...13
Phosphorus…………………………………………….13
Nitrogen………………………………………………..14
Dissolved Oxygen……………………………………..15
Temperature……………………………………………15
Clarity………………………………………………….17
pH………………………………………………………17
Macroinvertebrates……………………………………..18
Sampling Procedures……………………………………………18
Water Quality Results…………………………………………..20
Macroinvertebrate Results………………………………………24
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Discussion……………………………………………………….28
Shoreline Inventory……………………………………………………..29
Discussion……………………………………………………….29
Shoreline Runoff Survey………………………………………………..30
Conclusion………………………………………………………………31
Recommendations……………………………………………………….32
References……………………………………………………………….33
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Table of Figures
Figure 1………………………………………………………………….2
Figure 2………………………………………………………………….4
Figure 3………………………………………………………………….5
Figure 4………………………………………………………………….7
Figure 5………………………………………………………………….9
Figure 6…………………………………………………………………11
Figure 7…………………………………………………………………13
Figure 8…………………………………………………………………14
Figure 9…………………………………………………………………16
Figure 10………………………………………………………………..17
Figure 11………………………………………………………………..19
Figure 12………………………………………………………………..20
Figure 13………………………………………………………………..21
Figure 14………………………………………………………………..22
Figure 15………………………………………………………………..24
Figure 16………………………………………………………………..27
Abstract
Bass Lake has been studied for many years by the Wisconsin Department of Natural Resources
(WDNR). Water quality monitoring on Bass Lake started in 1986 as a part of the WDNR Long
Term Trends Monitoring program. This summer the Bass Lake Rehabilitation District (BLRD)
wanted to do some of their own testing and hired an intern from the University of Wisconsin –
River Falls. The intern was supervised by the St. Croix County Land & Water Conservation
Department (LWCD). The lake was tested for nitrate, phosphate, pH, dissolved oxygen,
temperature, clarity, and macroinvertebrates. The BLRD also asked that an individual shoreline
inventory be taken for every land parcel. The tests and shoreline inventory helped to determine
the water quality of Bass Lake. Everything that was tested confirmed that Bass Lake is an
Outstanding Water Resource, but the phosphate level is too high and needs some attention.
Some serious action needs to be taken in trying to keep phosphate levels down in the lake. This
is something that can be done with home and land owner participation and something that will
benefit the lake for years to come.
Purpose
The purpose of the summer internship was to work with the BLRD and the LWCD to determine
the water quality of Bass Lake by testing for nitrate, phosphate, pH, clarity, and dissolved
oxygen, to survey individual shorelines, and to survey for stormwater runoff. All of these things
relate to the quality of Bass Lake. Along with the results of this study, Bass Lake volunteers
were trained to monitor the lake for years to come. Keeping a record of readings for many years
will allow the BLRD to know about problems or improvements to the lake and what, if anything
needs to be done.
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Background Introduction
Bass Lake is located in northwestern Wisconsin, in St. Croix County. It is a thermally stratified,
groundwater seepage lake (Figure 1) that is 416 acres
and has a maximum depth of 45 feet, according to the
WDNR in 2006. The Bass Lake watershed is 1,398
acres, which is relatively small compared to the lake
size. This is a three to one ratio and is a contributing
factor that leads to the quality of the lake.
Figure 1
Currently, Bass Lake is named an Outstanding Water Resource by the WDNR. An Outstanding
Resource Water is a surface water which provides valuable fisheries, hydrologically or
geologically unique features, outstanding recreational opportunities, unique environmental
settings, and is not significantly impacted by human activities (Wisconsin Administrative Code
NR 102.11). The one thing that threatens that is the phosphate concentrations. They have been
on an increase for many years now and some serious considerations need to be taken. The rapid
development on and close to the lake is causing problems with the quality of the water. The
increase in recreational traffic also contributes to the rising problem.
There have been many studies done on Bass Lake, all of which give different numbers for
acreage, depth, and water level. In 1992 there was a study done by the WDNR and the West
Central Wisconsin Regional Planning Commission that stated the lake was 441 acres and had a
maximum depth of 38 feet. According to a 2006 WDNR study the lake was 416 acres with a
maximum depth of 45 feet, and the WDNR website has Bass Lake as a 293 acre lake with a
maximum depth of 37 feet. The water level has fluctuated a lot in the past several years. The
lowest recorded level was in 1963 at 876.37 feet and the highest level was 888.25 feet in 1995.
This is a difference of 11.91 feet in 32 years (Konkel and Borman 1996).
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Geology of Bass Lake and the surrounding watershed
The rocks and soils that control movement and storage of groundwater in St. Croix County range
from the bedrock of Precambrian age to the glacial deposits, alluvium and soils of the Quaternary
age. Throughout most of the county the bedrock is overlain by glacial drift. The Bass Lake
watershed is overtop of a bedrock fault that runs from the northeast to the southwest through the
center of the lake (Figure 2). The bedrock that lies north and west of the fault is Cambrian
sandstone, the Trempealeau formation. This bedrock consists mostly of sandstone, shale,
siltstone, and dolomite. The bedrock that lies to the south and east of the fault is Ordovician.
The thickness of the glacial drift varies greatly, from 0’ on hilltops and road cuts to more than
450’ west of Bass Lake. The depth to the surface of the Bass Lake watershed varies from 0-200
feet (Figure 3).
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Figure 2
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Figure 3
Topography
The Bass Lake watershed has the characteristics of a typical end moraine of a glaciated area.
The watershed mostly is a rolling landscape with approximately 20% of the landscape as a C
slope (6%- 12%). Some of the gentler slopes in this category can be developed on with care, but
development of slopes approaching 12% can pose a serious problem with erosion and runoff.
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Steeper slopes in the D (12%- 25%) and E (20%- 35%) categories tend to ring the lake. About
266.8 acres of the watershed has a D slope and development is likely to cause major erosion and
runoff problems. Only about 62.9 acres of the Bass Lake watershed have E slopes, which many
of these are located on the heavily developed east bank of the lake (WDNR and West Central
Wisconsin Regional Planning Commission, 1992).
Soils
According to the St. Croix County Land Information Plan, an updated soil survey has not been
done since 1978 and will be done only when the NRCS schedule allows. There are three main
soil series that are within the Bass Lake watershed: Onamia, Chetek, and Burkhardt (Figure 4).
The Onamia series covers 12,818 acres of St. Croix County. This series also consists of gently
sloping to steep, well drained soils on outwash plains and areas of pitted outwash plains. It is a
fine loamy soil that lies overtop of sandy gravel. Native vegetation that is normally found
around this type of soil is white pine, sugar maple, and red oak. It has a moderate ability to hold
water and permeability is moderate in the subsoil and rapid in the sand and gravel.
The Chetek series covers 6,941 acres of St. Croix County. This series consists of sloping to
steep, somewhat excessively drained soils on knolls of pitted outwash plains. It is a course
loamy material that is overtop of sand and gravel. The native vegetation that is normally found
around this type of soil is red oak and white pine. The water holding capacity is relatively low
and permeability is moderately rapid in the subsoil and rapid in the substratum.
The Burkhardt series covers 16,936 acres of St. Croix County. This series consists of very deep,
somewhat excessively drained soils formed in 25 to 50 cm of loamy alluvium and in the
underlying sandy outwash. The native vegetation that is present in this series is mainly oak
savanna or native prairie grasses. The water holding capacity is low and permeability ranges
from moderately rapid in the loamy upper part to rapid in the underlying sand and gravel.
There are various individual soil types that are within these three groups. The most dominant
individual soil type in the Bass Lake watershed is OnD2, the Onamia-Antigo complex. The
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surface layer is mainly silt loam and loam, but is sandy loam on steep parts of the complex.
With this composition and with the typical slope (12%- 25%) runoff is rapid and the hazard of
erosion is severe. This is bad for agriculture and the absorption for septic tank fields is limited.
The next dominant soils type in the watershed is CoC2, the Chetek-Onamia complex. This has a
surface layer that is mainly sandy loam and loam, but with some small areas of silt loam and
loamy sand. This soil type is mostly found on the crests of knolls and has the tendency to be
more eroded than the Onamia soils. With the composition and slopes (6%- 12%) runoff is
medium and the hazard of erosion is moderate. There is some of this soil that is present on the
east side of the lake where there are slopes of 12%- 20% and this has very high potential for
rapid runoff and severe erosion.
The other soil type is found in the southern part of the watershed, which is BxD2, Burkhardt-
Sattre complex. This complex also is found near the crest of knolls and on steeper slopes. These
have a slope of 12%- 30%, which makes runoff and erosion rapid and severe.
The Emmert soil series is found in lesser amounts throughout the watershed. But is one to pay
attention to. This series occurs mostly on the eastern lakeshore and along the southwestern
shoreline. The eastern shoreline makes up the earliest and more densely developed areas. The
sandy makeup of the soil and the steep slopes limit road and septic tank absorption development
(WDNR and West Central Wisconsin Regional Planning Commission, 1992).
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Groundwater Hydrogeology
Bass Lake is a groundwater seepage lake that has no inlets or outlets and has little overland flow.
The only recharge that the lake gets is from groundwater inflow and precipitation. Evaporation
and groundwater outflow account for the loss of water from the lake. In the last four decades the
lake level has fluctuated by more than ten feet. In the early 1970’s high water levels flooded
many homes and roads. This lead to a study done by Rinaldo-Lee in 1978. The study used 32
wells to determine that groundwater flows to the west and ends up discharging into the St. Croix
River. The immediate area of Bass Lake has a more complex flow system tied to it. The
northern half of the lake is located in the regional flow through system; the southern half has
both the regional flow through system and a local recharge system to the upper glacial aquifer
(Figure 5). Most of the wells that were installed were destroyed or are now unstable, but in 1992
five wells on the south end of the lake remained useable and four wells were installed in
September of 1990 on the east side of the lake to determine groundwater inflow gradients
(WDNR and WCWRPC, 1992).
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Figure 5 (WDNR and WCWRPC, 1992)
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Aquatic Vegetation
An aquatic vegetation study of Bass Lake has been preformed annualy by Deb Konkel of the
WDNR. The results from the 1987-2006 study are attached as Appendix A. These results
indicate that there is a good species diversity. It also states that phosphorus levles have been on
the rise in the past few years.
Bass Lake Fish
Fish population surveys done by the WDNR have found a quality self-sustaining large mouth
bass and panfish fishery, which is supplemented by alternate year stocking of walleye
fingerlings. A copy of the DNR stocking report has been attached as Appendix B. The panfish
population that has been found includes bluegills, black crappies, yellow perch, and
pumpkinseeds. There are also northern pike, yellow and black bullheads, white suckers and carp
present (Engel, 1986). Bass Lake has had fish populations documented since 1953 with little
change occuring. Most years have shown a good populaiton of largemouth bass, walleye, and
panfish.
Mercury testing in fish has been done on Bass Lake. The WDNR focused their sampling efforts
on lakes that are popular with anglers, lakes that have a low pH or low alkalinity, areas where
mercury contaminated wastes have been dumped, or where long-term contaminant trends in fish
are being studied. With the size and different fish species present in Bass Lake, the WDNR
gives the following health advisories to the public:
• Women beyond their childbearing years and men may eat:
o Unrestricted- Bluegill, crappies, yellow perch, sunfish, bullheads and inland trout; o 1 meal per week- Walleye, pike, bass, catfish and all other species o 1 meal per month - Muskies.
• Women of childbearing years, nursing mothers and all children under 15 may eat:
o 1 meal per week - Bluegill, crappies, yellow perch, sunfish, bullheads and inland trout
o 1 meal per month - Walleye, pike, bass, catfish and all other species. o Do not eat - Muskies.
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Population
The number of people that now inhabit the Bass Lake area is greater than ever. In 1982 the West
Central Wisconsin Regional Planning Commission prepared a population projection for three
different places affecting Bass Lake (Figure 6) and the population from the U.S. Census Bureau
in 2000 was: St. Joseph- 3,436; Somerset- 2,644; St. Croix County- 63,155. The projection was
done again in 2004. According to the Wisconsin Department of Natural Resources Statewide
Comprehensive Outdoor Recreation Plan, St. Croix County has grown the most rapid at 44%
from 1990- 2004 and is projected to gain 22,680 residents between 2004-2020. This increase
will affect the amount of people living and recreating on Bass Lake.
Figure 6
POPULATION PROJECTIONS
1980 1990 2000 2010St. Joseph 2,180 2,657 3,150 3,760 Somerset 1,833 1,975 3,056 3,947 St. Croix County 43,260 50,251 64,853 79,093 (WCWPC, 1982)
POPULATION PROJECTIONS
2010 2015 2020 2025St. Joseph 4,172 4,456 4,746 4,957 Somerset 3,478 3,824 4,171 4,446 St. Croix County 80,779 87,967 95,202 100,806 (WCWPC, 2004)
Development
Most of the development on the east shoreline occurred during the 1950s. Building permits have
not been systematically collected or maintained by townships in the past and less than adequate
records have been updated by the Township of St. Joseph since 1979. According to St. Joseph
Township on August 27, 2007 there have only been about 3 new construction building permits
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and 5-10 major remodel building permits within the past ten years. The west side of the lake
contains most of the larger more wooded lots. These homes also tend to be year round homes
and the ones on the east side are more seasonal homes.
Shoreland Zoning in St. Croix County
The WDNR wrote NR 115 to meet the responsibilities of the Water Resources Act of 1966.
They did this to establish standards and criteria that must be met by county shoreland zoning
ordinances. St. Croix County defines a shoreland as all lands that fall within 300’ of a river or
stream or to the landward edge of the floodplain or within 1000’ of a lake, pond or flowage or
the St. Croix River. Appendix C has a copy of the St. Croix County Code of Ordinances as it
relates to shoreland zoning. Bass Lake and its watershed fall mostly within St. Joseph Township
and the northern half falls in Somerset Township. These two townships don’t have their own
shoreland regulations, so they must follow the county regulations. St. Joseph Township does
have regulations regarding lot size and number of residences on one given lot.
Recreational Use
Bass Lake is a heavily used recreation lake. It is located in the Mississippi River Corridor and
urban influences impact the region as visitors from the nearby Twin Cities metropolitan area
make use of the region’s recreational resources. Suburban development associated with the
greater Twin Cities metropolitan area in St. Croix and Pierce Counties continues to impact
recreation supply and demand across the region (WDNR Statewide Comprehensive Outdoor
Recreation Plan, 2005-2010). Both residents and non-residents use the lake for fishing, skiing,
and boating. Marty Engel of the WDNR has said that Bass Lake is felt to be a heavily used lake
in the area by local fish and game managers. This year a boat patrolman was hired to watch the
lake for people disobeying the law for the summer.
Sampling
Sampled Parameters
Phosphorus
Phosphorus occurs naturally in rocks and other mineral deposits. Figure 7 shows what the
phosphorus cycle looks like. During the natural process of weathering, rocks gradually release
phosphorus as phosphate ions which are soluble in water and the mineralized phosphate
compounds breakdown. In freshwater lakes it is considered the growth-limiting nutrient. When
levels are too high it causes algae blooms and this is what makes lakes eutrophic. Storm events
can cause the vertical infiltration of the phosphates into the groundwater system, but because of
soils affinity for phosphate, the soil mantle acts as a storage media. The non-point sources of
phosphates include: natural decomposition of rocks and minerals, stormwater runoff, agricultural
runoff, erosion and sedimentation, atmospheric deposition, and direct input by animals/wildlife.
Just one pound of phosphorus in runoff can result in 500 pounds of algae growth. Phosphates are
not toxic to people or animals unless they are present in very high levels. Digestive problems
could occur from extremely high levels of phosphate (Wilkes University).
Figure 7
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Ortho phosphate (PO4) is one of the types of inorganic phosphorus and is the most stable type of
phosphate. It is usually referred to as reactive phosphorus. This means that it is used by plants
and is produced by natural processes. This differs from total phosphorus (P), which entails all
three forms of phosphates in the environment: ortho phosphate, metaphosphate, and organically
bound phosphate. Phosphorus readings are taken in mg/L of phosphate. Since our readings were
in ortho phosphate, they had to be converted into phosphate. According to the EPA, in order to
convert ortho phosphate into phosphate, the PO4 needs to be divided by three.
Nitrogen
The nitrogen cycle in one of the most important processes in nature for living organisms (Figure
8). It makes up 78% of the Earth’s air and is an essential part of amino acids. Nitrate (NO3) is a
common inorganic form of nitrogen. Plants normally use nitrate as their source of the nitrogen
and so, nitrate is considered a nutrient for plants. Excessive concentrations of nitrate in lakes and
streams greater than about 5 milligrams per liter, depending on the water body, can cause
excessive growth of algae and other plants, leading to accelerated eutrophication or "aging" of
lakes, and occasional loss of dissolved oxygen. In most cases of excess nitrate concentrations,
the principle pathway of entering aquatic systems is through surface runoff from agricultural or
landscaped areas which have received excess nitrate fertilizer (USGS, 2007).
Figure 8
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Dissolved Oxygen
Dissolved oxygen is one of the best indicators of water quality. It can range from 0-18 mg/L and
it takes about 5-6 mg/L to support a diverse aquatic population. Oxygen enters the water by
direct absorption from the atmosphere or plant photosynthesis. The oxygen is used by plants and
animals for respiration and by aerobic bacteria which consume oxygen during the process of
decomposition. The oxygen reading tends to be lower in the early morning because
photosynthesis stops at night, stopping the production of oxygen, while animal/plant activity and
respiration continue. The level should increase during a normal sunny day, reaching a maximum
late in the afternoon. There are three main reasons why dissolved oxygen would decrease:
1. Increase in temperature, decreasing the amount of any gas that water can hold.
2. Respiration - All aquatic plants and animals use oxygen to respire, to break down food to
release the energy required for cellular activity. Even though plants photosynthesize and
produce oxygen during daylight hours, they, like animals, carry on respiration at night.
3. Decomposition - After death, all organisms decompose, and in this process the bacteria
use oxygen to break down the material. At times this can seriously deplete aquatic
oxygen, especially at night when the oxygen cannot be replaced.
(Chase, 1988)
Temperature
The rates of biological and chemical processes depend on temperature. Aquatic
organisms from microbes to fish are dependent on certain temperature ranges for their
optimal health. Optimal temperatures for fish depend on the species: some survive best in
colder water, whereas others prefer warmer water. Figure 9 shows just what temperatures warm
water fish prefer for different life stages. There are six main things that cause changes in
temperatures:
1. Weather
2. Removal of shoreline vegetation
3. Impoundments
4. Discharge of cooling water
5. Stormwater Runoff
6. Groundwater inflows
Figure 9
Species Life Stage Degrees (C°) Catfish Spawning 24 Incubate 29 Juvenile 32 Adult 32 Smallmouth Bass Spawning 18 Incubate 23 Juvenile 29 Adult 29 Largemouth Bass Spawning 21 Incubate 23 Juvenile None Given Adult 32 Bluegill Spawning 25 Incubate 34 Juvenile None Given Adult 32 Black Crappies Spawning 17 Incubate 20 Juvenile None Given Adult 27 Striped Bass Spawning 18 Incubate 24 Juvenile None Given Adult None Given White Bass Spawning 17 Incubate 26 Juvenile None Given Adult None Given Walleye Spawning 11 Incubate None Given Juvenile None Given Adult 28 (http://ndep.nv.gov/bwqp/file/recommended_temp_criteria06.pdf, 2006)
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Clarity
Water clarity is a measure of water quality related to chemical and physical properties. There are
two main parts related to clarity: true color (materials dissolved in water) and transparency
(materials suspended in water). The transparency is a good indicator of a lake’s algae presence.
Algae is natural and essential in water, but too much of it can cause some major problems. The
best times to test for water clarity with the secchi disc is between the months of June and August.
pH
The pH of water is a measure of the lake’s acid level. Hydrogen and hydroxide ions are what
make up water. The separation of these two ions allows water to be acidic, neutral, or alkaline.
The pH scale ranges from 0-14 making each range either an acid, neutral, or alkaline (Figure 10).
The largest variety of aquatic animals prefers a pH range of 6.5-8.0. pH outside this range
reduces the diversity in the lake, because it stresses the physiological systems of most organisms
and can reduce reproduction. Natural rainfall, exposed to C02 in the atmosphere, maintains a pH
of 5.6 in northwestern WI. Most fish could not reproduce in even the best rainfall if rainwater
pH were not raised by the chemical buffering of the carbonate system in streams, lakes and the
surrounding watershed.
Figure 10
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Macroinvertebrates
A macroinvertebrate is any insect without a backbone that can be seen by the naked eye. One
way to find out the water quality of Bass Lake was to look for indicator species. According to
the Merriam Webster dictionary an indicator species is defined as; an organism or ecological
community so strictly associated with particular environmental conditions that its presence is
indicative of the existence of these conditions. Macroinvertebrates are used in streams to
indicate good or bad water quality. The science isn’t as accurate for lakes. Macroinvertebrates
that indicate good water quality are those that need higher levels of dissolved oxygen and are not
tolerant of pollution. Macroinvertebrates that indicate bad water quality are those that can live in
lower levels of dissolved oxygen. The presences of macroinvertebrates that indicate bad water
quality only indicate bad water quality if they are the only types of macroinvertebrates found.
These “bad water” macroinvertebrates will live in high levels of dissolved oxygen as well as low
levels of dissolved oxygen.
Sampling Procedures
Water quality samples and readings were collected biweekly and weekly at four randomly
chosen sites from June 2007 to August 2007 (Figure 11). Phosphorus, nitrogen, dissolved
oxygen, temperature, clarity, and pH were sampled at these sites.
Water chemistry samples for phosphorus and nitrogen were collected every other week at each of
the four locations. They were collected in plastic containers and stored in a cooler with ice packs
for no longer than 24 hours. The samples were then taken to the UWRF chemistry lab and tested
for nitrate and ortho phosphate with a Hach DR/2400 meter. Each sample was tested following
the manual instructions (Appendix D). A 10ml sample was used for each test. The glass testing
tubes were washed out with distilled water after every use. A sample site was chosen randomly
for running duplicate tests. This helps ensure the accuracy of the results. The results were then
entered into an Excel spreadsheet and graphs were charted. Since the phosphorus was read in
ortho phosphate, it had to be converted into phosphate. According to the EPA, in order to
convert ortho phosphate into phosphate, the PO4 needs to be divided by three.
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Figure 11
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Dissolved oxygen, temperature, clarity and pH were sampled weekly at these sites. A YSI-55
meter was used at the lake’s surface for measuring dissolved oxygen and temperature. The meter
was calibrated and samples taken according to the manual instructions. Clarity depth was
measured using a secchi disc. The procedures outlined in the WDNR Citizen Lake Monitoring
Training Manual were followed for taking secchi disc readings. Transparency readings weren’t
taken every week due to bad weather and equipment problems. The pH was measured using an
Oakton double junction waterproof pHtestr 1. The meter was calibrated and samples taken
according to the manual instructions.
Macroinvertebrates were also collected to give an idea of just what was living in Bass Lake.
Sixteen traps were built out of plastic mesh and then filled with basalt rock (Figure 12). a long
string was then connected to each trap which was used to secure the trap to the shoreline. Eight
traps were put out at a time at four different locations (Figure 13). They were left for a week at a
time and then collected and sorted.
Figure 12
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Figure 13
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Water Quality Results
Eleven weeks of water quality data were taken at Bass Lake this summer (Figure 15). Appendix
E has a list of all the graphs associated with those results. These results are what determine the
lake to be Oligotrophic, Mesotrophic, or Eutrophic (Figure 14). The Merriam Webster
Dictionary defines these three terms as:
• Oligotrophic- having a deficiency of plant nutrients that is usually accompanied by an
abundance of dissolved oxygen
• Mesotrophic- having a moderate amount of dissolved nutrients
• Eutrophic- a body of water that becomes enriched in dissolved nutrients (as phosphates)
that stimulate the growth of aquatic plant life usually resulting in the depletion of
dissolved oxygen
Figure 14
Quality Phosphorus ChlorophyllSecchi Disc
Index ug/L ug/L ft. Oligotrophic Excellent <1 <1 >19 Very Good 1-10 1-5 8-19 Mesotrophic Good 10-30 5-10 6-8 Fair 30-50 10-15 5-6 Eutrophic Poor 50-150 15-30 3-4
(Konkel, 2006)
The phosphate readings that were found are the ones that show some concern. Just about every
time that ortho phosphate was tested, the readings were over the DNR recommended levels. Past
studies have shown that phosphorus has been on the rise since 1998. The highest ortho
phosphate concentration was over the HACH scale, which is 10.0 mg/L, the lowest was 0.05
mg/L, and the mean was 0.54 mg/L. These levels show Bass Lake to be in the Eutrophic status.
The concentrations of nitrate are all under DNR recommendations, 5 mg/L, and don’t show to be
a threat to the lake. The highest concentration was 4.91 mg/L, the lowest was 0.78 mg/L, and the
mean was 3.09 mg/L.
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Dissolved Oxygen levels are higher than the needed amount for living organisms to survive. The
highest reading was 9.63 mg/L, the lowest was 7.38 mg/L, and the mean was 8.52 mg/L. There
isn’t 11 weeks worth of dissolved oxygen readings due to a problem with equipment. The last
sampling day, 8/22/07, the DO meter was used to find the hypolimnon. It was found it to be
around 26-30 feet.
The secchi depth results are in the good range according to the Trophic Status table. All of the
secchi disc depths fall in the Oligotrophic or Mesotrophic status. The majority of these readings
fall into the Mesotrophic category. The highest reading was 13.25 feet, the lowest was 4.5 feet,
and the mean was 7.4 feet.
pH stayed around the same almost all summer. Theses results also match previous studies that
have been done and they show Bass Lake to be on the alkaline side. This puts Bass Lake in the
hard water category and these lakes tend to have more abundant aquatic plant growth.
Bass Lake water quality samples June - August 2007
Sample Locations Kelly's Swamp Site
1. Elevation 891 ft N 45° 04.664' W092° 38.818
3. Elevation 893 ft 45° 03.441'
W092° 38.807'
5. Elevation 891 ft 45° 03.712'
W092° 38.623' 2. Elevation 892 ft
45° 03.785' W092° 39.156'
4. Elevation 885 ft 45° 03.290'
W092° 38.803' Recommended phosphorus concentration from DNR for lake quality = .01mg/L Recommended nitrate concentration from DNR for lake quality= 5mg/L Nitrogen Equation: y= -0.39000806x + 38.6077357 *Used to convert the absorbancy number given by the Hach DR/2400 to mg/L Temperature Conversion: F°= 1.8(C°)+ 32 pH in Wisconsin lakes usually between 4.5-8.4
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Figure 15
Date Sample Location Time
Dissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
Nitrate (ABS)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 10:08 NA NA 77 38.59 0.07 0.02 Sample 2 9:55 NA NA 90 38.49 0.55 0.18 Sample 3 9:40 NA NA 74 38.6 0.07 0.02
6/12/2007
Sample 4 9:30 NA NA 72 38.59 0.05 0.02
Date Sample
Location TimeDissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
Nitrate (mg/L)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 1:07 NA NA 6/24 69 4.91 0.12 0.04 Sample 2 1:14 NA NA 6/24 81 1.32 0.3 0.1 Sample 3 1:27 NA NA 6/24 66 3.47 2.07 0.69
6/19/2007
Sample 4 1:35 NA NA 6/24 63 3.59 0.98 0.33
Date Sample
Location TimeDissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
Nitrate (mg/L)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 8:25 NA 25.4 63 2.22 0.28 0.09 Sample 2 8:41 NA 25.5 69 3.23 0.07 0.02 Sample 3 8:50 NA 24.8 54 4.64 1.04 0.35 Sample 4 9:00 NA 24.7 63 3.55 1.48 0.49
6/26/07
Duplicate #4 9:01 2.02 1.04 0.35
Date Sample
Location TimeDissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH
Sample 1 8:19 NA 23.4 78 9.4 Sample 2 8:31 NA 24.4 69 9.1 Sample 3 9:07 NA 24.3 69 9.1
7/5/07
Sample 4 9:16 NA 24.6 69 9
25
Date Sample Location Time
Dissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH Nitrate (mg/L)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 10:33 NA N/A 102 9.2 3.78 0.5 0.17 Sample 2 10:39 NA N/A 120 9.1 1.79 0.32 0.11 Sample 3 10:44 NA N/A 153 9.1 2.65 0.07 0.02 Sample 4 10:51 NA N/A 159 9.1 2.14 1.4 0.47
7/10/2007
Duplicate #2 10:40 2.84 0.1 0.7
Date Sample
Location TimeDissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH
Sample 1 10:11 8.84 24.6 N/A 9.4 Sample 2 10:25 8.77 25.1 N/A 9.2 Sample 3 10:33 8.51 25.1 N/A 9.2
7/20/2007
Sample 4 10:35 8.44 25.4 N/A 9.1
Date Sample Location Time
Dissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH Nitrate (mg/L)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 9:30 8.88 25.7 126 9.2 1.4 0.11 0.04 Sample 2 9:54 8.55 25.2 138 9.1 4.44 0.48 0.16 Sample 3 10:06 8.57 25.1 123 9.1 2.1 0.74 0.25 Sample 4 10:17 8.63 25.2 123 9.1 3.08 0.26 0.09
7/25/2007
Duplicate #4 10:17 2.69 0.39 0.13
Date Sample
Location TimeDissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH
Sample 1 11:20 9.22 26.5 N/A 9.4 Sample 2 11:30 9.63 26.7 N/A 9.3 Sample 3 11:42 8.87 26.7 N/A 9.2
8/4/2007
Sample 4 11:50 8.67 26.7 N/A 9.2
26
Date Sample Location Time
Dissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH Nitrate (mg/L)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 12:05 9.46 26.6 84 9.4 0.78 0.12 0.04 Sample 2 12:16 9.21 26.4 87 9.3 3.23 1.01 0.34 Sample 3 12:31 9.18 26.3 96 9.3 3.43 over over Sample 4 12:46 8.93 26.3 93 9.3 3.27 0.63 0.21
8/9/2007
Duplicate #2 12:16 2.69 0.96 0.32
Date Sample
Location TimeDissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH
Sample 1 10:52 7.86 24.8 78 9.3 Sample 2 11:15 8.1 25.1 75 9.2 Sample 3 11:27 7.85 25.3 87 9.2
8/17/2007
Sample 4 11:19 7.86 25.3 87 9.2
Date Sample Location Time
Dissolved Oxygen (mg/L)
Temp (C°) Transparency (in)
pH Nitrate (mg/L)
Ortho Phosphate
(mg/L)
Phosphate (mg/L)
Sample 1 12:17 7.38 22.2 N/A 9.4 3.08 0.09 0.03 Sample 2 11:54 7.74 22.5 N/A 9.3 4.21 0.16 0.05 Sample 3 11:40 7.85 22.4 N/A 9.3 2.96 1.03 0.34 Sample 4 11:45 7.5 22.6 N/A 9.3 3.96 0.79 0.26
8/22/2007
Duplicate #1 12:17 3.27 1.01 0.34
Macroinvertebrate results
Almost all of the macroinvertebrates found were indicators of good water quality. All of the
other macroinvertebrates that were found didn’t really have an effect on the water quality status
in terms of indicator role. Figure 16 will show macroinvertebrates that were found and if they
were indicators of good water quality. Appendix F has all of the numbers at each site that was
found.
Figure 16
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Discussion
All of the following testing results were good: pH, nitrate concentration, transparency, dissolved
oxygen, and temperature. Temperature plays a important role on a lot of the things that were
tested. The last day of testing, 8/22/07, the temperature dropped more than it had all summer.
This has to do with all of the rain storms that St. Croix County had endured. All of the
stormwater runoff caused the lake’s normal temperature to decrease. The storms also caused a
drop in secchi depth clarity. The dissolved oxygen dropped due to the storms because there had
been fewer sunny days compared to the rest of the summer. The aquatic plant life had not been
getting as much light as before. This reduced the amount of photosynthesis while reparation
stayed the same.
The high levels of phosphorus can be linked to the amount of aquatic plant life that exists in Bass
Lake. Phosphorus clings tightly to soil particles and vegetation. With the water level of Bass
Lake being low and the boater use being high, boat motors will stir up more sediment and soil
from the bottom of the lake and cause spiked levels of phosphate. There were a lot of very
windy days on the lake this summer and all the wind and wave action stirs up sediment. Not
allowing your land to have an adequate buffer zone allows for soil erosion, stormwater runoff,
and a greater amount of fertilizer, which in return adds more phosphorus to the lake. Any type of
building or road causes impervious surfaces. The percent of these items compared to your lot
size gives your impervious surface percent and it should not exceed 10%. In all actuality it
should stay around 1%-3%. Any time you can reduce this percent, you should. This can be done
by removing unneeded buildings or roads that are not in use.
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Shoreline Inventory In order to start this inventory, a master inventory sheet had to put in place. This inventory sheet
was made through research of other shoreline inventories that had been done at other places.
After this sheet was made a point system had to be developed for it. This delegated a certain
amount of points for each item according to the benefit of shoreline conservation.
There were 105 parcels of land that were inventoried this summer. Each parcel was given a
score based on how they rated on the monitoring sheet guidelines (Appendix G). This inventory
was done during the last week in June 2007 and the first week in July 2007. It was a visual
survey that was done by boat and some of the information was provided by home owners. The
inventory was also based off of studies done in the past and some guidelines put in force by the
WDNR. Lots were scored on the following:
• Shoreland buffer extending 35’ back from the Ordinary High Water Mark
• A viewing corridor of 35’
• Critical sites that were tested in 2005 by St. Croix County
• DNR regulations
o Structures in water per 50’ of shoreline
o Objects below Ordinary High Water Mark
There was a possible 98 points that could be earned. Nine lots scored 78 or above, forty nine lots
scored 77-58, twenty six lots scored 57-38, and twenty one lots scored 37 or below. A copy of
the individual surveys is located with the BLRD and LWCD.
Discussion
This survey ultimately told us that the majority of shoreline owners are keeping their shorelines
as natural as possible. There were some land owners that don’t seem to be very concerned about
the effects that they have on the lake quality due to things like; mowing all the way to the
shoreline, no natural vegetation between lake and home, allowing erosion to go into the lake, and
disobeying the DNR regulations for shoreline properties. This survey proved to be a good thing
for the BLRD to ask for this summer. We have received calls from people asking what they can
do to improve their score and future things that they could do. Neighbors have also been talking
to each other to compare scores and talking about what they can do to improve.
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Shoreline Runoff Survey On August 22, 2007 a visual survey was done to see just where runoff problems might be
occurring around the lake. These places were ones that might cause major runoff from storms.
They were evaluated and recommendations were given.
The first sight was at the east entrance of Awatukee Trail. There is a culvert that runs under the
road and over towards the lake. This was put there a long time ago when there was farmland on
the upper half of that road. It was assessed and the conclusion was that the drainage basin that
was on the other side of the culvert was deep enough to hold approximately 5 feet of water. This
basin would have to become very full, very fast before any overflow would occur.
The second sight was Bass Lake Trail. This runoff occurred form the gravel road that lead back
to a few homes. This gravel washout ran along the north side of 132nd Ave., but then started to
cut back to the other side of the road towards the woods. The topography of the road at the south
end of the lake allows for the gravel to run away from the lake.
The third sight was the ditch that runs along the Wilson property. This used to be where 132nd
Ave. connected to the east side of the lake. This ditch did show signs of runoff, but it is a
problem that could be fixed. Recommendations were made at that point in time and are listed at
the end of this report.
The last runoff sight that was observed was the detention basin at the boat launch. This basin
was in good working order. This could be seen, because it had caught a lot of water from the
previous storms that week. The concrete lip that is in place between the parking lot and slope of
the boat launch it raised enough to keep the flow of water heading towards the detention basin.
30
Conclusion Bass Lake is a thermally stratified groundwater seepage lake that has had fluctuating lake levels
for many, many years. With the watershed to lake ratio, residents need to be careful of their
daily activities. Encouraging conservation and best management practices will educate the
public on what they can do to help. The BLRD would like to keep the lake as an Outstanding
Water Resource, so they looked into what they could do as a community. They have purchased
their own testing equipment and they will be using it to test the water quality for summers to
come. They are also going to be working with the WDNR, through the Self-Help Monitoring
Program, to have water chemistry samples tested and secchi disc readings recorded. The work
that was done this summer will give the BLRD a step in the right direction to maintaining the
water quality. The residents of Bass Lake have shown an interest in protecting the water and this
will help for future generations.
31
32
Recommendations Bass Lake already has good water quality and the thing to do now is to keep it that way and work
on reducing phosphate levels. In order for Bass Lake to stay an Outstanding Water Resource, I
recommend:
1. Continue monitoring and chemical testing of the water. This can be done through the
WDNR Self-Help Lake Monitoring Program.
http://dnr.wi.gov/org/water/fhp/lakes/selfhelp/
2. Plant some vegetation in the road ditch at the south end of the lake. This will help with
stormwater runoff. Some guidelines to follow are:
a. Seed in Spring (4/15-6/1) or Fall (8/1-8/21) b. Seed mix for that area:
i. Smooth Bromegrass (Bromus inermis), 0.5lbs ii. Creeping Red Fescue (Cestuca rubra), 0.14lbs iii. Alfalfa (Medicago sativa), 0.14lbs iv. Red Clover (Trifolium pretense), 0.14lbs
c. Install one erosion logs
3. Properly maintain all private roads around Bass Lake to ensure no gravel runoff.
4. Participate in St. Croix County’s program for soil testing. Encourage all lake
residents to have their soil nutrient levels tested.
5. Keep in contact with the parks department to make sure the boat landing is being
maintained so that stormwater runoff filters into the detention pond.
6. Encourage residents to join WAL (Wisconsin Association of Lakes) and sign up for
their e-mail newsletter. www.wisconsinlakes.org
7. Remind residents and boaters to participate in Clean Boats, Clean Waters Program.
http://www.uwsp.edu/cnr/uwexlakes/CBCW/
8. Encourage residents to maintain a natural shoreline.
9. Encourage residents to attend meetings and picnics to keep themselves informed on
what is happening around the lake.
10. Impact on lake quality occurs when the watershed has 7% impervious surface. Contact
Town and County representatives about keeping impervious surface low within Bass
Lake’s Watershed. Encourage conservation development.
11. Update the signs that are posted at the boat launch. The better people can read them, the
better they will be at obeying the rules and regulations.
12. Contact the Bureau of Water Resources Management Groundwater Section and try to
have a study conducted to determine the nutrient contribution of septic systems.
References Chase, Valerie. Dissolved Oxygen, Carolina Tips, May 1, 1988.
"Dissolved Oxygen", LaMotte Company brochure, 8/24
Engel, M.P. Basic Fish Survey of Bass Lake- St. Croix County. Wisconsin Department of Natural Resources Project FM02BAL FM687. September 1988.
Konkel, Deborah and Susan Borman. 1996. Changes in the Aquatic Plant Community of Bass
Lake, St. Croix County, 1987-1996. Wisconsin Department of Natural Resources. Murphy, Sheila. General Information on Phosphorus. 2007. 24 Aug. 2007 < http://bcn.
boulder.co.us/basin/data/BACT/info/TP.html> St. Croix County Planning and Zoning Department. St. Croix County Code of Ordinances Land
Use Development.2003. 27 Aug. 2007 < http://www.co.saint-croix.wi.us/Ordinances/Ch%2017%20SUBCHAPTER%20III%20Shoreland.pdf>
U.S. Environmental Protection Agency. 2007. 23 Aug. 2007 <http://www.epa.gov/owow/
monitoring/volunteer/stream/vms54.html>
U.S. Environmental Protection Agency. 1997. 23 Aug. 2007 < http://www.epa.gov/ volunteer/stream/stream.pdf>
USGS: Science for a Changing World. 2007. 24 Aug. 2007 <http://interactive2.usgs.
gov/faq/list_faq_by_category/get_answer.asp?id=641> Wilkes University Center for Environmental Quality Environmental Engineering and Earth
Sciences Phosphates and Water Quality. 24 Aug. 2007 < http://www.water-research.net/phosphate.htm>
Wisconsin Department of Natural Resources, West Central Wisconsin Regional Planning
Commission. Phase I Diagnostic and Feasibility Study for Bass Lake St. Croix County, Wisconsin. 1992.
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