Extended Detention Basin (Dry Pond)

Dry detention ponds are basins with outlets that have been designed to store stormwater runoff for a specified period of time after a storm, usually 48 hours, to allow particles and pollutants to settle to the bottom. Unlike wet ponds, these facilities do not have a large permanent pool. The impounded water is discharged through an outlet that provides for prolonged release. 

Dry ponds can be planted with wetland vegetation to provide additional nutrient and pollutant uptake. Dry ponds that incorporate a shallow marsh or wetland to improve pollutant removal are known as extended detention wetland basins or two stage detention ponds. It is important to determine whether standing water is by design or an indication that maintenance is required.



  • Conduct routine mowing

  • Keep embankments and slopes stable

  • Remove sediment as necessary

  • Manage vegetation, seed and stabilize bare spots

  • Fill animal burrows

  • Keep trenches / basin free of debris and trash

  • Keep risers, spillways and outlets clear


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