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 to infiltrate and clean polluted stormwater prior to its discharge.

Monitoring the results of these activities provides critical information to know how well stormwater management actions are working.

Cooperative monitoring is underway for jurisdictions that are subject to municipal stormwater permits.

  • Stormwater Action Monitoring (SAM) is a collaborative program focused on Western Washington pollution source control and effectiveness studies. It includes studies on Puget Sound-focused receiving water.
  • Eastern Washington's stormwater group is a coordinated program focusing on effectiveness studies of best management practices.
  • Southwest Washington’s Lower Columbia status and trends efforts study small streams in the Lower Columbia basin.

We provide tools to support 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

Stormwater permits require discharge and outfall monitoring

Monitoring is required for businesses and jurisdictions to stay in compliance with construction, industrial, and municipal stormwater permits. Monitoring for construction and industrial permittees is done at the point of discharge or from the site.

For municipal stormwater permittees, there are so many hundreds of outfalls that monitoring all of them is not feasible.


Standard operating procedures (SOPs)

We have three SOPs specific for outfall monitoring used under the municipal permits that follow our quality assurance guidelines.

Industrial Construction Sand & Gravel
Municipal stormwater outfall monitoring results