On February 16, 2007, Cowlitz County was issued a National Pollution Discharge Elimination System (NPDES) phase II Municipal Stormwater Permit. This permit requires the County to develop and implement a Stormwater Management Program to reduce stormwater runoff and pollution. The area affected by the permit is the unincorporated urban area of Cowlitz County (PDF) adjacent to the cities of Longview and Kelso. The areas affected by the permit are shown in green on the map.

Stormwater Management Plan - 2023 update (PDF) 

Stormwater Management Action Plan -2023 (PDF)

Ordinance Forming Stormwater Utility (PDF)

Resolution Setting Utility Rate (PDF)

Cowlitz Clean Waters Organization

The Cowlitz County Stormwater Management Program is focused on six minimum measures to increase public awareness and stormwater stewardship. The six minimum measures include: 

1. Public Education and Outreach

  • Identify and educate public on local impacts of stormwater runoff.
  • Distribute educational materials to the community (Brochures, Signs, Stencils).
  • Media releases.
  • Measure the results over time.

2. Public Involvement and Participation

  • Seek public comments on the Stormwater Management Plan.
  • Citizen Stormwater Advisory Committee.
  • Engage citizen volunteer groups (Workshops, Stream Cleanups).
  • School programs.

3. Illicit Discharge Detection and Elimination

  • Implement regulations to prohibit illicit discharges.
  • Develop program to detect and address non-stormwater discharges.
  • Establish a hotline to report illicit discharge activities.
  • Map the stormwater conveyance system with outfall locations.

To Report:

You can use the following contacts to report spills and dumping into surface waters or storm drains or Illicit sewer and waste water connections to the stormwater drainage system:

  • Cowlitz County Department of Public Works at 360-577-3030 or  email
  •  Water Pollution Hotline at 360-578-0900  
  • Department of Ecology  at 360-407-6300 or email

IDDE Ordinance (PDF)

4. Construction Site Stormwater Control Measures

  • Implement regulations on erosion and sediment control.
  • Site plan review procedures
  • Adopt portions of the 2005 Western Washington Stormwater Manual or an equivalent.
  • Post Construction Stormwater Control Measures

5. Implement regulations on runoff quality and quantity.

  • Affect new development and redevelopment
  • Structural and non-structural Best Management Practices
  • Long term maintenance of Best Management Practices
  • Site inspection & enforcement procedures

6. Pollution Prevention and Good Housekeeping for Municipal Operations

  • Develop and implement an operation and maintenance program to reduce runoff pollutants from municipal operations.
  • Equipment and material storage
  • Street sweeping
  • Litter pickup
  • Fleet maintenance areas
  • Employee education and training programs