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Stormwater: What You Need to Know

Stormwater runoff from construction activities can have a significant impact on water quality by contributing sediment and other pollutants to creeks, streams, lakes, etc. Under the Federal Clean Water Act, The National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating sources of pollution that discharge into waters of the United States. Federal regulations relating to the NPDES Stormwater Permit Program require operators of certain sized construction projects to obtain authorization to discharge stormwater under an National Pollutant Discharge Elimination System (NPDES) construction stormwater permit:

• Phase I Stormwater regulations published in 1990 required construction activities that disturbed five or more acres of land to obtain NPDES permit coverage.
• Phase II Stormwater regulations, which became effective March 2003, expanded the requirement to obtain permit coverage to include discharges of stormwater from construction sites between 1 and 5 acres. Find Your State Phase II Forms and Instructions

As the federal regulations specify, state permits may allow for two types of waivers for the Phase II construction sites (those disturbing between one and five acres). The first waiver is available when the "rainfall erosivity factor" or erosivity index value (EIV) is less than five (download Low Erosivity Waiver Certification Form). The second waiver is available for sites discharging to state waters with a Total Maximum Daily Load (TMDL) where it has determined that pollutant allocations for construction activities are not needed. All waiver requests must be approved in writing. EPA is currently developing guidance on the implementation of these waivers.

Construction projects that disturb one or more acres are subject to three major requirements:

• Submit a permit application (or Notice of Intent) prior to the start of construction.
• Develop, submit, and fully implement an erosion and sediment control plan that is approved prior to initiating any on-site activities. This plan specifies the measures that will be put in place to prevent and/or control erosion and sediment run-off.
• Submit a Notice of Termination when the following criteria have been met: final stabilization of the site has been achieved as defined in the permit, all temporary erosion and sediment controls have been removed, and no potential remains for construction-related sediment discharge to surface waters.