Industrial Stormwater General Permit

What is the Industrial Stormwater General Permit?

The state requires industrial facilities to obtain stormwater permit coverage in an effort to reduce or eliminate stormwater pollution and other impacts to the surface waters of the state.

Industrial facilities must obtain permit coverage if the facility conducts any activities listed in the permit and the facility discharges stormwater to a surface water body; if the facility’s existing NPDES permit does not address all of the stormwater discharges; or when an inactive facility has significant materials that remain on-site and are exposed to stormwater.

Unpermitted facilities that meet the above criteria must obtain permit coverage through the Department of Ecology. Ecology could also require additional facilities to seek permit coverage if it finds that the facility is a significant contributor of pollutants or if it finds that the facility is reasonably expected to violate any water quality standard. The facility owner/operator must develop and implement a stormwater pollution prevention plan (SWPPP) that includes the best management practices necessary to prevent or reduce the pollution of waters of the state as well as comply with the permit’s applicable sampling guidelines. The SWPPP should include a site map, detailed assessment of the facility, description of the best management practices, a spill prevention and emergency cleanup plan, and the facility’s sampling plan. Generally, facilities must conduct quarterly samples of discharges and submit the results to the Department of Ecology within 45 days of the end of the reporting period. The facility must submit reports even if no sample was collected whether it is because there was no discharge or collection was not possible within the first twelve hours of the discharge. If a facility exceeds a sampling benchmark that is outlined in the permit, the facility must complete the appropriate level of corrective action and update the SWPPP as necessary. Additional sampling requirements and corrective action guidelines are available in the permit.