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Series: Colorado Water Law Basics #13 - Detention vs. Retention Stormwater Ponds
There are two types of stormwater ponds: detention ponds and retention ponds. Detention ponds only detain water for a short period of time, then release the water to a natural watercourse, while retention ponds retain the water for an indefinite period of time. The way a detention pond works is there is typically an outlet at the lowest point in the pond that allows the water to slowly drain through the pond. Therefore, detention ponds typically are dry between storm events. Conversely, retention ponds typically have a weir or some type of overflow device which allows discharge of water but only when inflow exceeds the capacity of the pond and the water level rises above the outlet weir or pipe. As such, retention ponds are typically maintained at a relatively constant water level.