Retention Pond

Definition

A retention pond (or retention basin) is a type of artificial lake used to manage stormwater runoff to prevent flooding and downstream erosion, and improve water quality in an adjacent river, stream, lake, or bay. Retention ponds are designed to hold water indefinitely, with excess volume flowing into a designated spillway or outlet structure.

Typically, these ponds serve a dual purpose: they help with flood control by absorbing excess stormwater during peak times and acting as settling basins, and they improve water quality by holding pollutant-carrying runoff long enough for sediments and contaminants to settle to the bottom.

Examples

Residential Development Example: A new housing community includes a landscaped retention pond in its design. It holds stormwater runoff from roofs, driveways, and streets. This water gradually infiltrates into the ground or evaporates, reducing the burden on the municipal sewer system.
Commercial Property Example: A shopping complex installs a retention pond to manage runoff from large parking areas. The pond is stocked with aquatic plants to aid in the removal of pollutants before water is slowly released to nearby watercourses.
Recreational Use Example: A retention pond is created as a central feature in a city park. Not only does it manage stormwater, but it also provides habitat for wildlife, supporting recreational activities such as fishing and bird watching.

Frequently Asked Questions (FAQs)

What is the difference between a retention pond and a detention pond?

A retention pond is designed to hold a specific amount of water indefinitely, releasing water only when exceeding its capacity. A detention pond temporarily holds water and releases it at a controlled rate to mitigate flood risk.

How do retention ponds improve water quality?

Retention ponds allow pollutants and sediments to settle to the bottom, reducing the load of these contaminants in the water that eventually flows out of the pond. They also provide a habitat for aquatic plants that can absorb pollutants.

Are retention ponds beneficial for wildlife?

Yes, retention ponds can create a habitat for a variety of aquatic plants and animals, enhancing local biodiversity. They can support fish, birds, insects, and other wildlife.

What maintenance is required for a retention pond?

Maintenance includes regular inspection, removal of accumulated sediments, controlling invasive plant species, and ensuring the outlet structures are functioning correctly.

Can retention ponds be used for recreational purposes?

Yes, many retention ponds are designed to enhance aesthetic value and recreational opportunities such as fishing, bird watching, and even small boating activities, provided they meet safety standards.

Detention Pond: An open basin designed to temporarily hold stormwater and release it at a controlled rate to prevent flooding.
Stormwater Management: Methods used to manage the quantity and quality of stormwater to prevent flooding, erosion, and water pollution.
Wetland: Natural or artificial areas saturated with water, either permanently or seasonally, where plants and animals have adapted to wet conditions.

Online Resources

References

Suggested Books for Further Studies

“Stormwater Management for Smart Growth” by Allen P. Davis and Richard H. McCuen
“Design and Construction of Urban Stormwater Management Systems” by the American Society of Civil Engineers (ASCE)
“Principles of Water Quality Management” by W. J. McElyea

Real Estate Basics: Retention Pond Fundamentals Quiz

### What is a primary function of a retention pond? - [x] To hold water indefinitely and only release excess water at a certain level. - [ ] To temporarily store water and release it slowly. - [ ] To act as a habitat for marine life. - [ ] To filter drinking water. > **Explanation:** A retention pond is designed to hold a specific amount of water indefinitely, releasing excess water when it surpasses a certain threshold. It differs from other water management structures like detention ponds, which are temporary. ### Can retention ponds help in improving water quality? - [x] Yes - [ ] No > **Explanation:** Retention ponds improve water quality by allowing sediments and contaminants to settle at the bottom, and by supporting aquatic plants which absorb pollutants. ### Which term contrasts directly with retention ponds? - [x] Detention Pond - [ ] Wetland - [ ] Reservoir - [ ] Lake > **Explanation:** Retention ponds and detention ponds serve different purposes. While retention ponds hold water indefinitely, detention ponds are designed to temporarily hold water after a storm. ### What wildlife advantages do retention ponds offer? - [ ] None - [ ] Only for birds - [x] They can create a habitat for various wildlife - [ ] Only for fish > **Explanation:** Retention ponds can create a habitat for a diverse range of wildlife, including birds, fish, and various aquatic plants. ### What kind of maintenance is typically necessary for retention ponds? - [x] Periodic sediment removal and inspection of outlet structures - [ ] No maintenance is needed once installed - [ ] Only aesthetic maintenance like mowing grass - [ ] Frequent vacuuming of the pond’s bottom > **Explanation:** Retention ponds require regular maintenance which includes periodic sediment removal, inspection and upkeep of outlet structures, and sometimes controlling invasive species. ### Can retention ponds be used for recreational activities? - [x] Yes, if they meet safety standards - [ ] No, they are strictly functional - [ ] Only those over 50 acres in size - [ ] Only in residential zones > **Explanation:** Many retention ponds are designed to enhance recreational opportunities such as fishing, bird watching, or small boating activities, provided they meet safety standards. ### What is the main difference between retention and detention ponds in terms of water holding time? - [ ] Retention ponds do not hold water - [x] Retention ponds hold water indefinitely - [ ] Detention ponds hold water indefinitely - [ ] There is no difference > **Explanation:** Retention ponds are designed to hold water indefinitely as opposed to detention ponds, which are designed for temporary water storage. ### Why are retention ponds important in flood control? - [x] They absorb excess stormwater - [ ] They increase runoff - [ ] They divert water into other streams - [ ] They only serve an aesthetic purpose > **Explanation:** Retention ponds absorb excess stormwater during peak times to prevent flooding, thus playing a critical role in flood control. ### Can homeowners have retention ponds on their property? - [x] Yes, if properly designed and permitted - [ ] No, they are only for commercial properties. - [ ] Only if they own more than 2 acres of land. - [ ] Only in urban areas. > **Explanation:** Homeowners can have retention ponds on their property as long as they are properly designed, permitted, and maintained according to local regulations. ### What role do aquatic plants play in retention ponds? - [x] They help in pollutant absorption and water quality improvement. - [ ] They are only for aesthetics. - [ ] They reduce the water level. - [ ] They provide no real function. > **Explanation:** Aquatic plants in retention ponds absorb pollutants and nutrients, contributing to the overall improvement of water quality.

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