Detention Basins

Detention basins can be an important feature in your neighborhood to reduce flooding and maintain healthy waterways.

No one wants to deal with a flooded basement or maneuver around submerged streets after a storm. Unfortunately, the risk of flooding increases with suburban development—native vegetation, soil, and landscape depressions that store stormwater are replaced with impermeable surfaces such as roads, parking lots, and rooftops. Rainwater easily runs off these surfaces, putting more strain on our waterways and stormwater infrastructure.

Detention basins, also called detention ponds or retention ponds, are important structures that help prevent flooding. A detention pond is a man-made area that temporarily holds stormwater until it slowly releases into a local waterway.

A detention pond with a vegetative buffer.

Benefits of Detention Basins at a Glance

  • Reduce the rate at which stormwater enters local waterways. By temporarily storing stormwater, a detention pond can prevent rivers and streams from overflowing.
  • Prevent flooding in homes. Since detention ponds capture stormwater run-off from surrounding landscapes and rooftops, stormwater collects in the basin instead of homeowners’ properties.
  • Help to keep pollutants and sediment out of rivers and streams by allowing them to settle at the bottom of the detention pond. However, pollutants and debris can degrade a detention pond’s water quality, often leading to murky water and a thick layer of algae.

Common Issues with Detention Basins

Detention basins require regular maintenance to function well. A well-kept detention pond can manage stormwater in your neighborhood and be a beautiful spot for residents in the area, especially if it’s surrounded by native flowers.

The following are signs that a detention basin needs maintenance:

Algae

Stormwater run-off carries nutrients from fertilizers, sediment, animal waste and other sources into the detention basin. An increase in available nutrients allows algae to flourish. Abundant algae impacts aquatic life by blocking sunlight and decreasing oxygen levels in the water.

Shoreline Erosion

If the detention basin does not have any deeply rooted plants to stabilize the soil, shoreline erosion can occur. The eroded soil adds nutrients like nitrogen and phosphorus into the water, encouraging algae growth. Learn more.

Blocked Inlet and Outlet Structures

Sometimes inlet and outlet structures fill with trash, sediment, or overgrown vegetation, blocking water flow and making the area around a detention pond more susceptible to flooding. Learn more.

Invasive Species

Invasive plants like giant reed/phragmites, cattails and reed canary grass can fill in a detention pond by trapping sediment. As detention basins are filled in, they no longer provide the same amount of flood storage capacity as they were designed to hold. Learn more.

What Can You Do?

Since detention basins release water to local waterways, the condition of detention ponds affects water quality, the health of your local watershed and of your community. Homeowners Associations (HOAs) are responsible for the maintenance of their stormwater ponds, but residents also have an impact on the condition of detention basins. Here’s what you can do to keep your neighborhood detention basin in good shape:

  1. Properly dispose of trash and recyclables. When taking walks around your neighborhood, consider picking up litter to prevent it from ending up in the detention pond. 
  2. Do not dump anything into the detention pond or storm drain, and be mindful of how you dispose of yard waste.
  3. Limit lawn chemical use to what is necessary (and reduce usage if possible!). Stormwater run-off will wash chemicals used on lawns into detention basins. Since this source of water is not cleaned by a water treatment plant, chemicals washed into the detention basin will eventually end up in our local waterways. These chemicals harm aquatic life and wildlife that live in and around that body of water.
  4. Keep grass long near the shoreline of the detention pond. A vegetative buffer deters geese, limits the amount of chemicals and debris that enter the basin, and prevents shoreline erosion.
  5. Be responsible for picking up your pet’s waste. Any pet waste that is left on the ground can be picked up by stormwater run-off and introduced into the detention basin. Animal waste contains bacteria and nutrients that will degrade the water quality and affect aquatic life living in the detention basin.
  6. Talk to your HOA about planting a native buffer. A vegetative buffer of native plants around a detention basin can beautify your neighborhood while preventing contaminants, like chemicals, litter, and pet waste, from reaching the water. 
  7. Educate your neighbors about the purpose of a detention basin and how our everyday actions can have an impact. Share how they can contribute to a well-functioning detention basin that regulates stormwater run-off while adding aesthetic value to your neighborhood!

Go Native! The Benefits of Naturalized Detention Basins

A native buffer, or strip of native vegetation, can be added around the shoreline to restore a deteriorating detention pond. A native buffer around a detention basin…

  • Reduces shoreline erosion. A native buffer, made up of native plants with deep root systems, reduces the risk of shoreline erosion by stabilizing the soil.
  • Minimizes water contamination. A dense native buffer also reduces the amount of chemicals, such as herbicides and pesticides, from entering the detention basin (and eventually downstream bodies of water) through stormwater run-off. Native plants, well adapted to local environmental conditions, do not require the use of herbicides or pesticides.
  • Requires less maintenance. Having a native buffer around a detention pond also decreases the amount of mowing required. Grasses should be allowed to remain long around native vegetation to create a dense buffer, reducing the amount of chemical run-off entering the detention basin.
  • Discourages unwanted wildlife and animal waste contamination. Having a native buffer serves as a barrier to discourage pesky wildlife, such as geese, from lingering around the detention basin. The buffer also helps block animal waste from entering the basin and local waterways.
  • Adds aesthetic value to the neighborhood. A native buffer can create a beautiful area for the community. A beautiful and well-maintained detention pond can increase property values.
A naturalized detention pond.

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