An Evaluation of Stormwater Management in a Watershed of Minnesota
Valley National Wildlife Refuge
Bruce Wilson, Professor
Brad Hansen, Senior Scientist
Todd Schmidt, Graduate Student
Dave Warburton, U.S. Fish and Wildlife Service
Vicki Sherry, U.S. Fish and Wildlife Service
Brian Ashman, Graduate Student
Funding Source
U.S. Fish and Wildlife Service, Environmental
Contaminants Program
Objective
The overall goal of the study is to investigate the
magnitude of potential pollutants from Bloomington, Minnesota,
into the
Minnesota Valley National Wildlife Refuge. Specific objectives
are to:
- Collect water quality data from rainfall and snowmelt
events for different urban land uses that drain into
the refuge,
- Analyze the water quality data to document loading of
pollutants, and, if necessary,
- Recommend possible best
management practices to ameliorate problems.
Need or Impact
Long Meadow Lake, a Minnesota River floodplain
lake within the Minnesota Valley National Wildlife Refuge,
is an important breeding
and resting area for mallards, blue-winged teal, wood ducks
and other migratory waterfowl, wading birds, and shorebirds.
Refuge biologists have long suspected that the lake has not
produced waterfowl broods commensurate with its apparent capabilities.
Previous studies found invertebrate densities in the lake
slightly to significantly lower than in two other Upper Midwest
wetland
ecosystems and suggested disrupted aquatic vegetation communities
and stormwater runoff as potential causes.
Project Status
Seven monitoring stations have been established
in the watershed to measure the flow and concentrations of
contaminants. Stations
were selected to provide information on the runoff characteristics
for different land uses within the watershed and to provide
reliable assessment of the net input of contaminant discharging
into the Refuge. Stations also needed to be easily accessible,
and therefore could not be located in high-traffic areas.
ISCO automatic sampler 3700, ISCO flow logger 4150, and ISCO
area-velocity
sensor were installed to measure flow rates and collect samples
for water quality analyses. All instrumentation components
were installed within storm sewer/outlet pipe and manhole space.
Equipment was installed and made operational in time to capture
runoff data from storms starting in June of 2004. Water quality
samples were collected using a four-bottle configuration.
Sampling
started after a threshold water depth was exceeded. Six samples
of flow were placed in the first bottle using a time step
between samples of 5 minutes. Six samples were collected using
time
steps of 10 minutes, 15 minutes, and 30 minutes between samples
for the second, third, and fourth bottles, respectively.
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