Wastewater Discharge [Washington (State)]
State of Washington Geospatial Open Data Portal · 2025 Full Details
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Full Details
- Title
- Wastewater Discharge [Washington (State)]
- Description
- This data is included as part of the Environmental Health Disparities Version 3.0 map. To see this map, visit our webpage . For more technical information on this map and the model used, visit our technical report (link) . Background Wastewater is water that has been used by households, businesses, and industries including mining. Under the Clean Water Act (1948) and the Washington State Water Pollution Control Act (1945), sites must track and report pollutants in the wastewater they release. This treated wastewater is released as part of normal operations. Flooding, aging infrastructure, delays in implementing cleanup, and damage to pipes can cause untreated sewage to enter the environment. This results in pollution of nearby groundwater and surface water. People can be exposed to pollutants in contaminated water by drinking it or swimming in it. They can also be exposed by eating food that is grown with it or eating fish contaminated by pollutants. Warnings about this pollution may not be obvious, present, or use messaging that is within language or culturally relevant. Tribes and community organizations across Washington are leading efforts to reduce wastewater pollution through clean-up and restoration projects, as well as advocating for communities experiencing higher wastewater pollution. Tribal populations and communities that consume more fish and shellfish have a particularly high risk of cancer and other health impacts from contaminated fish. Tribal fish commissions and organizations are often the first responders and longstanding advocates when it comes to addressing these environmental health concerns. For more information on wastewater funding available for Tribes, see the EPA's list of federal water and wastewater resources for Tribes . Pollutants in the wastewater can create challenges and increase the cost for water treatment facilities. Water treatment failures and difficult-to-remove pollutants can ultimately lead to contamination of drinking water and crop irrigation water. Exposure to these pollutants can cause health issues. These include high blood pressure, cancer, and waterborne infections. People with fewer financial resources are often unable to afford health insurance or medical care. As a result, their health is more impacted by exposure to wastewater pollution. Finally, these pollutants also have a strong impact on wildlife, shellfish, and fish populations. Chinook salmon, a culturally important species, experience decreased growth rates and long-term reproduction impacts when exposed to wastewater discharge. Other factors such as warm waters, presence of dams, storm water runoff, and other factors impacting the waterways compound stressors associated with wastewater discharge. Evidence Discharge from wastewater sites can contaminate surface water and groundwater. This pollution is associated with a wide range of health issues. Chemicals used for wood preservation can increase high blood pressure [1]. Nitrates from fertilizer runoff can increase the risk of cancer, thyroid disease, and birth defects [2]. Tribes experience significantly higher risks of diabetes, heart disease, and other health issues that stem from contaminated fish or not having access to traditional foods. This measure also likely underestimates the risk to Tribal communities. Internal surveys have estimated that many Tribal members eat 10 to 100 times more fish than the EPA's average estimate. [3]. Ultimately, wastewater discharge can enter the drinking water system through infrastructure damage and underinvestment, often in connection to systemic racism. Across the United States, small community water systems that serve low income and historically minoritized communities are the most likely to have health-based violations of the drinking water standards due to lack of staffing and resources [4]. Water systems serving Tribal populations are also more likely to be underfunded, leading to a greater risk of exposure to wastewater discharge in drinking water [5]. These disparities stem from racist housing and development policies, which cause communities with the highest pollution burden to also have the least funding to support drinking water infrastructure [6]. Wastewater discharge impacts the endocrine system, brain function, stress levels, and metabolism of Chinook salmon [7]. Data source EJSCREEN's 2024 wastewater discharge estimates Methods This measure quantifies the impact of certain chemicals in wastewater discharge considering the risk of each chemical to human health and the concentrations that humans could be exposed to. It was taken directly from EJSCREEN's 2024 wastewater discharge measure. First the toxicity-weighted concentration in each stream segment is calculated. This is the sum of each monitored chemical's concentration multiplied by its toxicity. The toxicity of each chemical is based on the chronic human health impacts it causes. The chemicals and toxicities included in this analysis were established under section 313 of the Emergency Planning and Community Right-to-Know Act (EPCRA) in 1986. An estimated dose is calculated for each stream segment by modeling how humans could be exposed to the pollutants through drinking water or eating contaminated fish. This was multiplied by the inverse distance to the center of the census block. A maximum score of 10 was used for all distances under 0.1 km. This was then multiplied by the census block's population. Census blocks were added together for a census tract score. Pollution data comes from Discharge Monitoring Reports and Toxic Release Measure data from sites that discharge wastewater. In Washington, many of these sites are municipal wastewater (sewage) treatment plants, stormwater treatment sites, industrial sites, fish hatcheries, some Super Fund sites, and hydroelectric sites. For more information on the permit process and requirements, please refer to EPA's list of National Pollutant Discharge Elimination System permits. For more information on how this measure was calculated, refer to EJSCREEN's Technical Documentation . Caveats This measure does not include risk data for all contaminants. This measure includes only chemicals listed in the Toxics Release Inventory from section 313 of the EPCRA. This measure uses wastewater discharge from sites that are required to report to national databases. This measure does not include water pollution from: Discharge from on-site septic systems. Runoff from roads, agriculture, and industrial sites that directly enters streams and lakes. Therefore, this measure may underestimate the actual risk of exposure to wastewater discharge within Washington. The Risk-Screening Environmental Indicators (RSEI) model uses multiple assumptions to estimate the risk of exposure to pollution in water bodies. The model uses the number of fishing licenses in an area to estimate the number of people exposed to wastewater discharge by eating fish. They assume that 5% of all families with a fishing license consume fish at a higher "subsistence fishing" level. However, this metric is likely to significantly underestimate the risk on Tribal lands where fish are a traditional food. Internal surveys have estimated that many Tribal members eat 10 to 100 times more fish than the EPA's average estimate [3]. The methodology uses where people live as opposed to where they fish. This measure is aggregated across the census tract and does not represent each individual community within the tract. These data should always be supplemented with local data and equitable engagement for more accurate insights. This measure does not reflect the quality or safety of public drinking water supplies. Sources Karouna-Renier, N., Rao, K., Lanza, J., Davis, D., Wilson, P. (2007). Serum profiles of PCDDs and PCDFs, in individuals near the Escambia Wood Treating Company Superfund site in Pensacola, FL. Chemosphere, 69(8), 1312-9. Ward, M.H., Jones, R.R., Brender , J.D., de Kok , T.M., Weyer , P.J., Nolan, B.T., et al. (2018). Drinking Water Nitrate and Human Health: An Updated Review. International Journal of Environmental Research and Public Health, 15(7):1557. O'Neill, C. (2007) Protecting the Tribal Harvest: The Right to Catch and Consume Fish, 22 J. ENVTL. L. & LITIG. 131. https://digitalcommons.law.seattleu.edu/faculty/542 . Fedinick , K., Taylor, S., Roberts, M., Moore, R., Olson, E. (2019). Watered down justice. Washington DC: Natural Resource Defense Council Report. Levin, R., Villanueva, C.M., Beene, D., Cradock, A.L., Donat-Vargas, C., Lewis, J., et al . (2024). US drinking water quality: exposure risk profiles for seven legacy and emerging contaminants. J Expo Sci Environ Epidemiol, 34, 3-22. https://doi.org/10.1038/s41370-023-00597-z Wakhungu, M., Abdel- Mottaleb , N., Wells, E., Zhang, Q. (2021). Geospatial Vulnerability Framework for Identifying Water Infrastructure Inequalities. Journal of Environmental Engineering, 147(9). Ball, S.C., Meador, J.P., James, C. A., McIntyre, J. K., (2024): Exposure of juvenile Chinook salmon to effluent from a large urban wastewater treatment plant. Part 1. physiological responses. Aquaculture and Fisheries, 9(3), 355-66. https://doi.org/10.1016/j.aaf.2023.06.006
- Creator
- WADOH
- Publisher
- State of Washington Geospatial Open Data Portal
- Temporal Coverage
- Last Modified: 2025-07-21
- Date Issued
- 2025-07-08
- Rights
- Neither the Washington State Department of Health (WADOH), nor any agency, officer, or employee of the WADOH warrants the accuracy, reliability or timeliness of any information published by this system, nor endorses any content, viewpoints, products, or services linked from this system, and shall not be held liable for any losses caused by reliance on the accuracy, reliability, or timeliness of such information. Portions of such information may be incorrect or not current. Any person or entity who relies on any information obtained from this system does so at their own risk.
- Access Rights
- Public
- Format
- ArcGIS FeatureLayer
- Language
- English
- Date Added
- February 02, 2026
- Provenance Statement
- The metadata for this resource was last retrieved from State of Washington Geospatial Open Data Portal on 2026-02-02.
Cite and Reference
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Citation
WADOH (2025). Wastewater Discharge [Washington (State)]. State of Washington Geospatial Open Data Portal. https://geo.wa.gov/datasets/0e0e81a2c6334016bc84474326f3e9ba_0 (web service) -
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