# Detention Pond — Utility Construction Glossary

A stormwater basin that temporarily holds runoff and releases it through an outlet structure at a controlled rate, draining to empty between storms. A retention pond, by contrast, holds a permanent pool of water.

## Frequently asked questions

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

A detention pond is dry between storms. It fills during a rainfall event and drains down through an outlet control structure, and its purpose is to limit peak discharge rate. A retention pond holds a permanent pool, releasing only through infiltration, evaporation, or a higher overflow, and it provides water quality treatment as well as rate control.

### What controls how fast a detention pond drains?

The outlet control structure — usually some combination of an orifice plate, weir, or riser sized so the post-development peak discharge does not exceed the pre-development rate for the design storms. An emergency spillway handles events larger than the design storm.


## Related terms

- [underground-detention-system](https://www.dunninfrastructuregroup.com/glossary/underground-detention-system)
- [catch-basin](https://www.dunninfrastructuregroup.com/glossary/catch-basin)
- [slope-stabilization](https://www.dunninfrastructuregroup.com/glossary/slope-stabilization)
- [infiltration](https://www.dunninfrastructuregroup.com/glossary/infiltration)

Detention controls the rate at which stormwater leaves a site, which is what keeps development from pushing flooding downstream.

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Source: https://www.dunninfrastructuregroup.com/glossary/detention-pond
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