The Industrial Stormwater General Permit applies to nearly 1,200 facilities across Washington.
The ISGP regulates stormwater discharges from industrial sites to receiving waters of the state. Requires most industrial sites in Washington to monitor, measure, and reduce stormwater pollution leaving their site.
Implements CWA and state law RCW 90.48.
It’s a combined state waste discharge permit and a NPDES permit.