What is a retention basin?
A retention pond or wet pond is a stormwater facility constructed through filling and/or excavation that provides both permanent and temporary storage of stormwater runoff. It has an outlet structure that creates a permanent pool and detains and attenuates runoff inflows and promotes the settlement of pollutants. Retention basins can be designed as a multi-stage facility that also provides extended detention for enhancing stormwater quality design storm treatment and runoff storage and attenuation for stormwater quantity management.