The data-driven path to clean water

Spring is a busy time for nature – trees are budding, flowers are blooming, baby animals are emerging from their nests and dens. It is also when the cleanest, ice-cold water is flowing from the Cascades and Olympics into watersheds and communities across the state. Perhaps spring is a time that has you thinking about water – where does it go, how much do we have, and how clean is it?

We’re thinking a lot about water these days, too. Of course, our team is responding to the drought emergency. We’re also working on our clean water grants and loans for this year. We even have people who are thinking about all 85 million data points we have on the state’s water quality for rivers, streams, lakes and marine waters.

We are wrapping our state’s Water Quality Assessment – that’s where all the data comes in – and are sharing an update on our work.

Last week, we sent Ecology’s latest Water Quality Assessment to the U.S. Environmental Protection Agency (EPA) for approval. This week, we opened our ‘Call for data’ so we can start work on the next water quality assessment.

What does Ecology do with 85 million data points?

Data helps us prioritize water clean up efforts and project funding, update permit requirements, understand the effectiveness of restoration and pollution prevention actions, and it can help communities better understand the water that surrounds them.

One of our state’s most significant water-related data efforts is the Water Quality Assessment. The Assessment is an interactive online tool that pulls together existing data for fresh and marine waters as a resource for Tribal, federal, state, and local governments, universities, and other organizations. This data helps us determine water quality conditions so these groups can design monitoring programs, water quality improvement projects, and share successes in these efforts.

For this Assessment, Ecology evaluated over 10 million data points from 30 federally-recognized Tribes. Kim Bray, the Natural Resources Director for the Hoh Indian Tribe, shared more on the role the Water Quality Assessment plays in larger clean water efforts and how it supports Tribal work to protect Treaty-reserved resources. 

"Many Tribes in Washington retain off-reservation Treaty Rights to hunt, fish, and gather in their usual and accustomed areas. To improve conditions of and ensure protections for Treaty-reserved aquatic resources, Tribal biologists across the state manage long-term, large-scale water quality monitoring programs that often extend well beyond reservation boundaries. Submitting data collected during off-reservation monitoring efforts for inclusion into the Water Quality Assessment is one way that the Hoh Tribe partners with the Department of Ecology to preserve and restore marine and freshwater resources."  Kim Bray, Hoh Indian Tribe Natural Resources Director

Ecology leads Washington’s Water Quality Assessment

The federal Clean Water Act requires states to perform a Water Quality Assessment every two years to track how clean the rivers, lakes, and marine water bodies are. Ecology has delegated authority to implement the Clean Water Act in Washington. We place assessed water bodies in categories that describe the quality of the water and status of any needed cleanup. The Assessment helps us use state resources more efficiently by focusing our limited resources on water bodies that need the most work. The Assessment houses the Clean Water Act required 303(d) list of impaired waters.

The Assessment we just submitted to EPA is referred to as the 2022 Assessment, because it picks up where the last Assessment left off (the 2018 Assessment was submitted to EPA in 2021). We actually have three Assessments in play at the moment: the 2018 Approved Assessment, the draft or Candidate 2022 Assessment, and the 2026 Assessment that we just opened for data submittals.

This month, we submitted our 2022 Assessment to the U.S. Environmental Protection Agency for approval. This is an important step in the process – Ecology’s Water Quality Assessment takes multiple years to go from start to approval by EPA. Only after the Assessment is approved by EPA can we use the data to drive our clean water work.

The full Assessment process includes:

• Policy updates
• Call for data
• Ensuring credible data
• Evaluating data to create a draft Assessment
• Tribal review
• Public review
• EPA submittal

Our Water Quality Assessment webpage explains these steps in more detail.

To do this work, we have an interdisciplinary team across the agency including data management experts, IT wizzes, environmental toxicologists, sediment scientists, and water quality experts.

We also use a data automation tool to help us with the data evaluation. While this tool has made it possible for us to evaluate millions of data points in a more timely manner, we still need humans to look at the results. For example, the tool can flag unusual results for us that we need to investigate and determine if the results are accurate.

During the Tribal and public review, we often have conversations with data submitters, which can result in us including more or different data in the assessment.

Jule Schultz, the Spokane River Waterkeeper, has helped bring more data into the assessment by involving community members in the effort.

"Including data collected by our local volunteer scientists in the Water Quality Assessment meant that local community members could contribute to high level studies in the Spokane River. With Ecology’s support, we identified turbidity pollution and brought it into the official recognition process—laying the groundwork for stronger protections and continued salmon recovery." Jule Schultz, Spokane River Waterkeeper

Once approved by EPA, we have our official list to work from when it comes to prioritizing our clean water work. Examples of how we use the Assessment include:

• Water clean up plans: We have an obligation to clean up polluted waters. We use a public prioritization process to help us determine how and where to use our limited resources combined with partners to improve water quality. Learn about water clean up plans.
• Water quality permitting: We manage more than 6,500 water quality permit coverages. Water quality data from the Assessment helps us determine permit requirements.
• Funding: Every year we award millions in grants and loans to support clean water projects. One of the considerations in our application review and ranking process is if the project will help a polluted waterbody.

Call for data

The submittal of one Assessment to EPA marks the beginning of the next. We opened our official “Call for Data” on Monday, May 5. While data can be submitted at any time, the Call for Data represents our official window in the Assessment cycle where we gather data for evaluation in the next Assessment. With the Call for Data, we are seeking new data collected between Jan. 1, 2015 and Dec. 31, 2024 for evaluation in the 2026 Assessment.

“Having data for the Columbia River reflected in the Assessment is really crucial for the City of Vancouver. We’ve received support from Ecology for our water quality monitoring and data collection efforts, and formed great local partnerships to get a more complete picture of the health of the river.”
Frank Dick, P.E., Wastewater Treatment Engineering Manager with the City of Vancouver

If you are interested in submitting data to EIM for use in the Assessment, email 303d@ecy.wa.gov and we will connect you with our EIM Data Coordinator. Data submitted before July 7, 2025 will be evaluated for the 2026 Assessment.

We use data gathered by Ecology and credible data for fresh and marine water from Tribal, federal, state, and local governments, universities, and other organizations submitted to EIM or the federal Water Quality Portal. To help ensure that the data we use is accurate, all data must meet our credible data requirements in Policy 1-11. 

To submit data

Interested in the quality of the water near you?

Our Water Quality Assessment is available online. We have an interactive map and database where you can look up information.

Using the Water Quality Atlas map, you can zoom in or search an address, then see if we have water quality data for nearby rivers, streams, lakes or marine water. The listing will include summary information on the pollutant or parameter (such as bacteria, temperature or a chemical), the waterbody name, and the Listing ID. You can view even more details by searching for Listing IDs in the Assessment Database.