The federal Clean Water Act (CWA) sets effluent limitations for discharges of pollutants.  "Pollutant" is defined in the CWA to include a variety of materials that may be discharged into water through human activities, construction or industrial processes, or other methods.

The Department of Ecology (Ecology) is delegated federal CWA authority by the United States Environmental Protection Agency (EPA).  Ecology also is the agency authorized by state law to implement state water quality programs.

The CWA establishes the National Pollutant Discharge Elimination System (NPDES) permit system to regulate wastewater discharges from point sources to surface waters.  "Point sources" are defined generally as discernable, discrete, and confined conveyances from which pollutant discharges can or do occur.  The NPDES permits are required for anyone who discharges wastewater to surface waters or who has a significant potential to impact surface waters.

A wastewater discharge permit places limits on the quantity and concentrations of contaminants that may be discharged.  Permits may require wastewater treatment or impose operating or other conditions, including monitoring, reporting, and spill prevention planning.  The NPDES permits are valid for five years but may be renewed.

In the NPDES permit programs, Ecology issues both individual permits (covering single, specific activities or facilities) and general permits (covering a category of similar dischargers).  These permits include limits on the quantity and concentrations of contaminants that may be discharged.  These permits also may require wastewater treatment or impose operating or other conditions. 

One category of general NPDES permits issued by Ecology is municipal stormwater general permits, issued in connection with stormwater that drains into waterways from surfaces such as parking lots, streets, and highways.  The municipal stormwater general permits are divided into different phases depending on the individual jurisdiction.  The Phase 1 municipal stormwater general permit regulates systems owned or operated by:

• Clark, King, Pierce, and Snohomish counties;
• the cities of Seattle and Tacoma; and
• the ports of Seattle and Tacoma.

The National Pollutant Discharge Elimination System municipal stormwater general permit issued by the Department of Ecology (Ecology) to a Phase 1 permittee must require the permittee to report certain information on an annual basis, including:

• using data obtained from the Department of Fish and Wildlife (WDFW), the amount of the land base within the permittee's jurisdiction, on both a percentage basis and an overall acreage basis, that is an impervious surface, and how that percentage and overall acreage has changed since the issuance of the previous permit;
• using data obtained from WDFW, the amount of the land base within the permittee's jurisdiction, on both a percentage basis and an overall acreage basis, that is covered by tree or other vegetation canopy, and how that percentage and overall acreage has changed since the issuance of the previous permit;
• using the formula developed by Ecology, which must be designed to cost-effectively capture a representative range of stream temperatures, the monthly median temperature of all waterbodies within the permittee's jurisdiction that have been designated as critical habitat under the federal Endangered Species Act for salmon, steelhead, or bull trout, and how those monthly median temperatures have changed since the issuance of the previous permit;
• a narrative description of factors in addition to urban heat islands that may have had a measurable impact on the temperature of all waterbodies within the permittee's jurisdiction that have been designated as critical habitat under the federal Endangered Species Act for salmon, steelhead, or bull trout in the report year; and
• a description of the permittee's approach to reducing the impact of the urban heat island effect on waterbodies within the permittee's jurisdiction.

Annually, Ecology must issue the following awards to permittees whose work to address the urban heat island effect best demonstrates innovation and achievement in each of the following areas:

• an award for innovative urban forest conservation and sustainability programs designed to reduce power loads during peak heat and cold weather events;
• an award for the most effective vertical garden installation, or programs that produce significant adoption of vertical gardens;
• an award to recognize the implementation of innovative green roof programs that increase the adoption of green roof technology;
• an award for the newest and most innovative development of reflective roof technology based on effectiveness of reducing stormwater runoff temperature;
• an award for the most innovative use of permeable pavement technology and adoption of permeable surfaces; and
• an award for restoring streams from pipes and buried locations under the urban core to natural channels.

 
Beginning in 2025 and continuing every year thereafter, Ecology, in consultation with WDFW, may award one or more permittees with the designation of "salmon-safe community" for that year, based on the permittee's achievements within the following metrics:

• the permittee's reporting and monitoring comply with the letter and spirit of the reporting requirements;
• the permittee has made objectively quantifiable progress with regard to implementing the urban heat island mitigation strategies identified above; and
• the permittee has achieved measurable gains toward salmon recovery in the waterbodies within its jurisdiction.