Stormwater management facilities are required pursuant to the Delaware Code. The State of Delaware adopted regulations in the early 1990s that require land developers to control the quantity of stormwater runoff for land development projects to the pre-development flow rates for specific storm events. The same regulations also contain requirements that are intended to manage the pollutant levels in stormwater runoff. The enforcement of these regulations has been delegated to New Castle County since July of 1991.
There are different types of stormwater management practices. The type that is implemented depends on site-specific conditions including the compatibility with the type of development, location in a drainage watershed, and existing land conditions. The following stormwater management practices are typical in New Castle County.