Stormwater Ponds

Ponds have been widely used for years to reduce the risk of flooding and handle stormwater runoff. Portions of Golden Valley’s stormwater system direct runoff and any tagalong pollutants (bits of metal, spilled oil and pesticides, fertilizers, pet waste, grass and leaves, etc) into stormwater ponds instead of Bassett Creek, Sweeney Lake, Twin Lake, Wirth Lake, or other natural waterways. The ponds allow time for pollutants to attach to sediment (sand and dirt) and settle at the bottom of the pond.

Most newer residential and business areas are built around ponds. Many of these ponds were not formed naturally, and they are not there solely for aesthetic purposes. To help control phosphorous and other stormwater runoff pollutants, Golden Valley's Surface Water Management Plan requires stormwater detention ponds and sound water management practices on all construction sites throughout the Bassett Creek Watershed. The objective is to reduce the pollutants flowing into Sweeney Lake, Twin Lake, Wirth Lake, Bassett Creek, and other water bodies in the watershed.

Ponds are vital to the health of our community. Although residents are strongly encouraged to minimize pollution, stormwater ponds help deal with it once it has entered the environment.

Several elements make stormwater ponds unique:

  • The main body is often 3 to 8 feet deep and varies in size depending on how much runoff isAnatomy of a Stormwater Pond directed into it. The greater the surface area of a pond, the more pollutants it can remove.
  • Two main pond components are inlet (where the runoff enters) and outlet (where the runoff exits) pipes. They must be far enough apart so pollutants have time to settle before leaving the pond. This is why stormwater ponds are usually oblong. A pond three times as long as it is wide allows the polluted sediment more time to settle before the outlet pipe releases the water.
  • Ponds are constructed with a shallow safety shelf around the edges. These shelves are often filled with aquatic plants to filter more pollutants and make the pond less attractive to swimmers and young children.
  • Where space permits, forebays are constructed between the inlet pipe and the main pond. A forebay, usually a 4- to 6-foot-deep basin, holds about 15 percent of the pond’s volume. As water flows from the forebay into the main pond, much of the polluted sediment is filtered out, providing for easier pond maintenance.

Stormwater Pond Contaminant Litigation FAQs

Together with several other Minnesota cities, the City of Golden Valley has filed a federal lawsuit against seven refiners of coal tar for allegedly contaminating numerous stormwater ponds with chemicals called polycyclic aromatic hydrocarbons (PAH).

The city is seeking damages to fund proper disposal of PAH contaminants.

PAH is found in coal tar sealant, which is a product that was commonly applied to driveways and parking lots before the State of Minnesota banned the sale and use of sealants containing PAH in 2015.

Regardless of the lawsuit’s outcome, the City plans to begin testing ponds for PAH in 2019. Cleanup will begin following testing.

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