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Water Quality Studies
The water column conditions in 22 out of 26 Lake Minnetonka bays that were
assessed in this study have conditions that are suitable to support moderate to optimal zebra
mussel growth based on high calcium concentrations (used for shell growth) and moderate
chlorophyll concentrations providing a suitable food source from algae. The lake bottom
conditions (substrate) are dominated by sand out to the mudline, where sediments then
transition to muck. This is not optimal zebra mussel substrate, but will support moderate
growth.
Report Summary
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A fish survey was conducted on October 20-23, 2009 at four sites within the 22 mile Minnehaha
Creek corridor. The dominant fish at all four sites were black bullheads. Carp, and dogfish. White suckers were common at those three sites
as well.
Overall fish biomass was dominated by low-oxygen tolerant species such as bullheads, carp,
and dogfish, which probably has an adverse impact on water quality in the creek and in the shallow
connected lakes such as Meadowbrook and Hiawatha.
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| Bathymetry is measuring or mapping the depths of a body of water. The data collected can be compiled into a topographic map. Upon the completion of the bathymetric mapping of Lake Minnetonka in June 2008, bathymetric mapping was conducted on Dutch, Gleason, Pierson and Schutz Lakes by end of the 2008 summer. Bathymetric mapping of Lakes Hiawatha and Nokomis are planned to be completed in summer 2009. |
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| MCWD in cooperation with the Minnetonka Yacht Club have installed a weather station located on Lighthouse Island on Lake Minnetonka’s Carson Bay. The weather station measures radiation, relative humidity, temperature, precipitation, and wind direction and speed. A webcam captures a view of Lake Minnetonka that looks out over the Lower Lake and Big Island. Data from the weather station is currently uploaded manually and will in the near future be available to view in real time online. |
The largest limestone bedrock spring in the Twin Cities, the spring flows about 144,000 gallons/day (Jeffery, 2000). A limestone well tower & pump house was built in the 1880s with a reservoir holding pond expanded by soldiers of Fort Snelling. The fort had access to the spring water until the 1940s (Jeffery, 2000). The reservoir flows underground through a culvert towards the Mississippi River. Concerns that the Hwy 55/Hiawatha Light Rail project may have altered flow in this historic site has led to weekly discharge monitoring by the MCWD. MCWD has been monitoring discharge at Camp Cold Water Springs since August 2006.
Jeffery, S. 2000. A History of Camp Coldwater. Preserve Camp Coldwater Coalition, Minneapolis, MN. http://www.preservecampcoldwater.org/susuhistory.htm. |
| MCWD maintains and operates tipping bucket precipitation gauging stations at 7 locations in and near the watershed district. In addition there are 2 citizen precipitation recorders who record precipitation data. The precipitation data is published in our annual Hydrological Data Report. |
| MCWD has two ISCO stormwater monitoring stations along Minnehaha Creek. Pressure transducers that measure water level will be connected to a data logger unit which is then connected to the ISCO stormwater sampling devices. During a storm event, if there is a rise in water level greater than 2” in 30 minutes, the pressure transducer will communicate the change to the data logger, which will trigger the stormsampler to begin sampling. The sampling is collected on a timed pace basis in order to collect the entire storm event from beginning to end. Currently there are no stormwater monitoring stations on the Six Mile and Painters Creek, but there are plans to add sites in the near future. |
| In 2007 the MCWD successfully installed land line phone telemetry at 3 locations along Minnehaha Creek, including the Grays Bay outfall , I-494 ramps, and the Browndale Dam. The data is transmitted back every 2 hours from Grays Bay and one daily download at I-494 and Browndale Dam to a designated MCWD computer at the office, allowing broadcast of 1) Lake Minnetonka water level, 2) discharge out of the Grays Bay Dam, and 3) discharge out of the Browndale Dam. Currently Grays Bay Dam discharge is estimated using engineering equations due to the difficulty of measuring discharge at the outfall. The net result of this equipment will be more accurate information available to the public regarding discharge levels and recreational safety along the entire length of Minnehaha Creek (in combination with the Web broadcast of discharge at Hiawatha Avenue provided by the USGS). The information will also be very useful in determining the best method to regulate discharges coming out of the Grays Bay Dam for recreational use and prevention of downstream flooding. |
| In partnership with Gleason Lake Association, MCWD began in 2007 a lake vegetation study to assess the extent and removal of curly leaf pondweed in Gleason Lake. Throughout the 3-year study, whole lake herbicide treatments have been applied in the spring and the growth of curly leaf pondweed has been assessed in the fall. After 2009, spot treatments of the herbicide will be applied to areas where curly leaf pondweed is still an issue. |
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