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Stormwater than runs off of impervious surfaces is transported via the stormsewer system into stormwater ponds and wetlands. This prevents flooding and protects the water quality of downstream waterbodies like Rice Creek and the Mississippi River by filtering out the sediment and other debris that washes into the stormsewer. Stormwater ponds are artificially excavated into dry areas or into naturally-occurring wetlands that form in low spots.
Stormwater ponds are designed to accumulate sediment in order to protect natural, downstream waterbodies. This sediment is washed from roadways into the ponds via the stormsewer system. If the sediment didn’t filter out in these stormwater ponds, it would be carried into Rice Creek and the Mississippi River and negatively impact the water quality and ecological function of these waterways. Naturally occurring leaf fall and vegetative cycles can also contribute to material accumulation within the stormwater ponds; however, this can be exacerbated by the illegal dumping of yard waste. As the yard waste decomposes, it contributes organic material and nutrients which increase the amount of algae leading to decreased oxygen and odor.
Stormwater ponds must be periodically dredged in order to function. A lack of access easements and a maintenance plan has prevented the City from performing the required maintenance on the stormwater ponds in the Farr Lake area.
The City reduces sedimentation through its bi-annual street sweeping program. As part of the Farr Lake Study, the City is also investigating the installation of hydrodynamic separators at strategic catch basins. These hydrodynamic separators are flow-through systems that are installed within the stormsewer piping to remove sediment before it’s discharged into the ponds. Periodically, a vacuum truck would be used to suck out the sediment.
Residents can prevent sedimentation by:
1) Cleaning catchbasins to prevent leaves and sediment from washing into the stormsewer system (visit Adopt-A-Drain.org to learn more).
2) Properly managing their yard waste by either contracting for yard waste service or bringing it to the Anoka County Composting Facility.
3) Planting their yard, and especially shorelines, with native plants whose long roots can help filter out sediment
It is not recommended that stormwater ponds be used for recreation due to their poor water quality and varying water levels. During the winter, flowing water entering the stormwater pond through the stormsewer system can create unstable ice conditions.
Wetlands provide a number of ecological functions including wildlife habitat, water quality improvement, flood storage, carbon sinks, and more. The Wetland Conservation Act prevents filling of wetlands or excavation beyond the natural depth in order to protect these functions.
The City’s role is to prevent flooding damage and manage the stormwater system to mitigate water quality degradation; however, this City needs access easements from the residents to reach the ponds to complete this work. Please indicate on this survey if you are willing to provide access to the ponds from your property.
Additional above-and-beyond work may require cost-share from residents. This could include vegetative management of the wetland for a wider diversity of plants, beautification of the stormwater ponds, etc. Please indicate on the survey what work you are interested in seeing and if you would be willing to cost-share with the City to achieve those goals.