Water Quality Treatment - The ponds store the stormwater for a short period of time to allow for sediments (that carry nutrients which adversely impact natural tributaries and rivers) to settle at the bottom of the ponds. This removal of sediments better protects the environment downstream and also ensures our drainage systems have adequate capacity and are not further impacted from sediment buildup (which could restrict flow).
Flood Control - The ponds provide an area to store stormwater from rain events and help to limit the rate of flow from the area to eliminate flooding downstream. The stormwater is collected within the City’s drainage system and directed to the ponds, where discharge from the ponds is limited by a discharge structure that restricts flow at a slower rate.
Steep sides: Retention ponds are built with side slopes that can make it difficult for a person to climb back out.
Dangerous currents: Strong currents after a storm at both inlet and outlet areas of a pond can also pose a danger, especially if protective bars or grating is built to close to the drain. These currents can be strong enough to hold a person pinned against the grating, preventing people who would otherwise be able to swim to safety, from doing so.
Dirty water: Since retention ponds collect runoff and storm water, they are designed to act as a filtration system before the water moves on into local rivers, lakes and streams. As such, the sediment collected in the depth of these structures can contain heavy metals and contaminates. They can also have toxic algae blooms which can threaten the lives of children and pets or cause serious illness if ingested or placed in direct contact with skin.