Stormwater monitoring

Stormwater runoff can flow directly into fresh or marine waters, or it may go into a storm drain system and continue through storm pipes until discharging into the environment. Stormwater management activities include keeping rainwater clean, and using best management practices at sites or regional facilities to treat or infiltrate water before it's discharged. Monitoring and tracking stormwater quality helps us understand how well these activities by permittees and/or best management practices are working. We partner with Puget Sound Partnership on the National Estuary Program and the strategic initiatives.

Discharge monitoring

Most of our permits require outfall or discharge monitoring by businesses and jurisdictions. This includes both individual or general construction and industrial permits, where monitoring is done at the point of discharge or from the site. The municipal stormwater permits both require discharge monitoring and options to continue discharge monitoring at a stormwater outfall.

We provide tools to support discharge monitoring for the state's construction, industrial, and sand and gravel permits, including:

  • Stormwater and best management practices monitoring studies
  • Discharge monitoring reports (DMRs)
  • Monitoring guidance, operating procedures, and resources for permits

How to sample stormwater discharges

Compliance monitoring can be required by the industrial, construction, municipal, sand and gravel, or boatyard permits. The data provides the information needed about how well a permit is working to manage stormwater and protect the water quality of the receiving water body.

Submitting discharge monitoring reports

Reporting your stormwater discharges is an important step in understanding compliance with a permit and impacts to fresh, marine, or groundwater. Discharge Monitoring Reports (DMRs) characterize important aspects of your system like stormwater volumes, pollutant concentrations, and suspended stormwater sediment.

The federal Clean Water Act permits we administer require permittees to submit DMRs to report pollution discharge data. Permittees are required to submit DMRs each reporting period even if no sampling or discharge occurred. Stormwater permit compliance data collected by permittees is stored in the Permit and Reporting Information System (PARIS) database. In PARIS, you can find current and historical permit data. WQWebPortal guidance.

Industrial general stormwater monitoring resources

Stormwater sampling manual for Industrial General Stormwater Permit holders.

Construction general stormwater monitoring resources

Sand & Gravel general stormwater monitoring resources

A guide for sand and gravel operators to estimate discharge and stream flows.