Water Quality

Washington has almost 74,000 miles of rivers and streams statewide, more than 4,000 lakes, and almost 3,000 square miles of marine estuaries. We work with engaged citizens, businesses, tribes, and environmental groups to reduce, prevent, and eliminate water pollution.

We carry out the federal Clean Water Act for the state, making sure that waters support recreation, business activities, supplies for clean drinking water, and the protection of fish, shellfish, wildlife, and public health.

Our core work consists of water quality permitting, water quality improvement projects, and clean water financial assistance. We maintain the state's database of polluted waters (Section 303d list). which is part of our Water Quality Assessment process.

We use public involvement processes to inform our decision-making. We rely heavily on feedback we receive from businesses, environmental groups, local governments, tribes, and citizens.

The Water Quality program's goals are to prevent and reduce water pollution, to clean up polluted waters, and engage citizens in the work to protect and restore water quality in Washington.

The program manages hundreds of millions of dollars in capital funds, 99.5 percent of which is passed through to local governments, tribes, and non-profits for infrastructure and land-based projects that benefit water quality.

A growing state with growing pollution problems

Washington's growing population is putting ever-increasing pressures on lakes, rivers, marine waters, and groundwater. Fish, shellfish, and other aquatic animals require clean water to survive. People need clean water to drink. But with more people, there is more pollution than ever.

The pollution threats are diverse. They include warm water temperatures, low levels of dissolved oxygen, low pH, toxics, and bacteria.

Several sources contribute to poor water quality, and chief among them is polluted stormwater runoff. Stormwater is rain and snow melt that runs off surfaces such as rooftops, paved streets, highways, and parking lots. As water runs off these surfaces, it can pick up pollution like oil, fertilizers, pesticides, soil, trash, and animal waste. The water is usually not treated and it drains downstream into lakes, rivers, and marine waters. Expanses of hardened surfaces in urban areas increase the quantity of peak flow runoff. Untreated stormwater can make water and shellfish unsafe for humans and other animals, and can harm fish and wildlife habitat.

Federal law requires states to identify sources of pollution in waters that fail to meet state water quality standards, so we develop water quality cleanup plans (Total Maximum Daily Loads, or TMDLs) to address those pollutants. The TMDL establishes limits on pollutants that can be discharged to the waterbody and still meet state standards.

We also administer a water quality permit system that places limits on how much pollution industries and municipalities can discharge. We set the bar for how clean the water needs to be with state water quality standards. Our goal is for all rivers, lakes, marine water, and groundwater to meet state water quality standards.

Toxic pollution is a growing concern threatening water quality. We are studying sources of toxic pollution and developing action strategies to clean up and protect water quality. In spite of our efforts to date, Washington already has a significant number of waterbodies, marine sediments, and groundwater polluted by an array of contaminants.

Pointsource water pollution

We regulate discharges of pollutants to surface and groundwater by writing and managing wastewater discharge permits for sewage treatment plants, industrial facilities, and other general categories of wastewater dischargers. We:

  • Help dischargers comply with existing permits.
  • Make permits understandable and effective in protecting water quality.
  • Work to increase the use of reclaimed water.

Clean up polluted waters

We help local communities and businesses clean up polluted waters to meet water quality standards. We:

  • Assess state waters and update the list of polluted waterbodies.
  • Work with communities to clean up nonpoint source pollution.
  • Identify Best Management Practices (BMPs) for nonpoint pollution sources.

Nonpoint source water pollution

Nonpoint pollution is one of the state's most serious pollution problems, and the most difficult one to solve. This pollution comes from diffused sources, is generated by every kind of land use, and has no specific regulatory tool (like a permit) to deal with it. Solving the nonpoint pollution problem will require everybody's behavior to change, as well as better land management and structural management practices. Here's what we're doing about it. We:

  • Work with partners to identify pollution problems, and then follow up with landowners to offer options and funding to help them fix water pollution problems.
  • Provide grants and loans to implement effective management practice that prevent pollution.
  • Make sure forest practices are on a path to meet water quality standards.
  • Provide a regulatory backstop to protect downstream users from the negative impacts of nonpoint source water pollution.


We help local governments build stormwater programs in cities and counties. Our stormwater permits cover municipalities, industries, and construction projects. We:

  • Help dischargers improve compliance with existing stormwater permits.
  • Work to ensure that having a permit is not a competitive disadvantage.
  • Help dischargers reduce contaminated stormwater run-off from their sites.

Financial assistance

We will award approximately $380 million in new water quality grants and loans and continue to manage approximately 600 active grants and loans this biennium to protect public health and the environment through water quality protection and improvement. We:

  • Provide effective and efficient financial and technical assistance to manage water quality projects with the highest benefit to human health and the environment.
  • Capture environmental data and demonstrate the environmental benefits of the grant and loan program.
  • Help grant and loan recipients properly manage public funds with a high level of integrity and accountability.
  • Effectively manage new stormwater capital improvement grants for cities and counties.
  • Continue to develop an ongoing, comprehensive, statewide stormwater financial assistance program for local governments.