What acreage size does NPDES Phase 1 pertain to?

The National Pollutant Discharge Elimination System (NPDES) Phase 1 pertains primarily to construction sites that disturb 5 acres or more. This regulation was established as a part of the Clean Water Act to control stormwater discharges from large construction activities, which can cause significant sediment and pollutant runoff into water bodies. The focus on 5 acres allows for a targeted approach in managing larger sites that have the potential for greater environmental impact due to the volume of land disturbance.

Phase 1 went into effect in 1990 and initially focused on larger sites, as these typically pose a higher risk for erosion and sedimentation compared to smaller disturbance areas. By regulating sites of this size, the NPDES aims to ensure that appropriate erosion and sediment control measures are implemented, helping to protect water quality and aquatic ecosystems from harmful effects.