Retention Ponds

Storm water runoff is the main contributor of non-point source pollution entering the Vermilion River.  During a heavy rain, pollutants such as pesticides, fertilizers, oil, and trash are rinsed from parking lots and yards into storm drains, ditches and coulees, eventually making their way into the Vermilion River.

Detention ponds are one way to mitigate the amount of storm water runoff generated by many sources on or around your property.  However, without regular maintenance they can fill with sediment and detritus from rotting vegetation and become dysfunctional.  If properly maintained, though, a detention pond can be a beautiful addition to a landscape.  Planting native plants along the edge will not only beautify the area further, they’ll also add valuable habitat for wetland creatures and other wildlife!

Detention ponds will collect storm water runoff from adjacent lands and prevent pollutants from reaching our streams and rivers.  They can be designed to filter off water over time or to retain water at all times.

Simple Planning To Prevent Common Problems  

1. Remove any invasive species which find their way into your detention pond as soon as possible.  Invasive species can quickly multiply out of control.  For example, water hyacinths can double in number every three weeks and take over the surface of a water body.  This situation can cause a reduction in the function of evaporation and a depletion of dissolved oxygen in the water, killing many of the pond’s desired species.
2. If your pond becomes overrun with invasive aquatic vegetation, they could cause the pond to become silted in as they die and sink to the bottom.  This detritus can cause your pond to become filled with sediment and cease to function properly.
3. Research the plants you’ll be using around and in your pond to be sure they are appropriate for your purpose and location.  
4. Invest in native plants for your pond.  They are less likely to take over because their biological controls are already present in our area.
5. A detention pond should be designed to be 5-10% the size of the total area draining to it.
6. Detention ponds placed in areas with highly contaminated runoff should be designed with an underlying impermeable liner to prevent such pollutants from leaching further into the groundwater.
7. Detention ponds do not only apply to newly-developed sites.  Storm water retrofit detention ponds can be incorporated into previously developed areas.
8. Detention ponds should be placed in an area which will allow the runoff to drain into the pond.  They function best in areas with a gentle slope.
9. Know your water table.  If the bottom of the pond is above the seasonal high water table, it may not consistently hold water.
10. Know your soil.  Soils with high clay content are more likely to hold water than loamy or sandy soils