Ponding

Ponds have been widely used for years to reduce the risk of flooding and handle storm water runoff. Portions of Golden Valley’s storm water system direct runoff and any tagalong pollutants (bits of metal, spilled oil and pesticides, fertilizers, pet waste, grass and leaves, etc) into storm water 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.

ducks on pondMost 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 storm water runoff pollutants, Golden Valley's Surface Water Management Plan requires storm water 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, storm water ponds help deal with it once it has entered the environment.

Anatomy of a Storm Water Pond

anatomy of a pond diagram

Anatomy of a Storm Water Pond
(click on photo for larger image)

Several elements make storm water ponds unique:

  • The main body is often 3 to 8 feet deep and varies in size depending on how much runoff is 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 storm water 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 four- to six-foot-deep basin, holds about 15% 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.

Pond Landscaping

Landscaping around storm water ponds is not just for good looks. Gentle side slopes encourage runoff to enter the pond and discourage anyone from accidentally entering. Natural, un-mowed landscaping with plants in and around the pond:

  • stabilizes the pond by preventing erosion
  • provides an environment for microorganisms that remove nutrients/pollution from the water
  • improves the pond’s appearance by hiding debris and water level changes
  • provides a habitat for insects, such as dragonflies, that eat mosquitoes
  • discourages geese from visiting and contributing to pollution
  • makes ponds less attractive for wading or swimming

Read more on landscaping around bodies of water »