Stormwater Discharges from Construction Activities
- Importance of Controlling Construction Stormwater Discharges
- Background on Permitting Protections
- EPA Finalizes Modification to 2022 Construction General Permit (CGP)
Importance of Controlling Construction Stormwater Discharges
When it rains, stormwater washes over the loose soil on a construction site, along with various materials and products stored outside. As stormwater flows over the site, it can pick up pollutants like sediment, debris, and chemicals from that loose soil and transport them to nearby storm sewer systems or directly into rivers, lakes, or coastal waters. EPA works with construction site operators to make sure they have the proper stormwater controls in place so that construction can proceed in a way that protects your community’s clean water and the surrounding environment.
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Background on Permitting Protections
What Construction Activities Are Regulated
A Clean Water Act permit is required for stormwater discharges from any construction activity disturbing:
- 1 acre or more of land, or
- Less than 1 acre of land, but that is part of a common plan of development or sale that will ultimately disturb 1 or more acres of land.
Construction activity includes earth-disturbing activities such as clearing, grading, and excavating land and other construction-related activities that could generate pollutants.
The Federal “C&D Rule” Permit Requirements
All NPDES permits for construction stormwater must address the minimum federal effluent limitation guidelines for the construction and development point source category (referred to as “the C&D rule”).
The C&D rule found in 40 CFR 450.21 establishes minimum NPDES effluent limitations, such as:
- Design, install, and maintain effective erosion and sediment controls, and pollution prevention measures, to minimize the discharge of pollutants;
- Stabilize disturbed areas immediately when construction has ceased and will not resume for more than 14 days;
- Prohibit the dewatering discharges unless managed by appropriate controls;
- Prohibit the discharge of:
- Wastewater from concrete washout (unless managed by appropriate control), or washout/cleanout of stucco, paint, form release oils, other wastewater materials;
- Fuels, oils, or other pollutants used for vehicles; and
- Soaps or solvents to wash vehicles and equipment.
EPA Finalizes Modification to 2022 CGP
EPA recently finalized a modification to its 2022 Construction General Permit (CGP) to cover stormwater discharges from construction activities in Lands of Exclusive Federal Jurisdiction. The modified permit was issued on April 8, 2025 and expires on the same date as the 2022 CGP was already set to expire, February 16, 2027. This permit covers stormwater discharges from construction activities in areas where EPA is the NPDES permitting authority.