Washington Nitrate Prioritization Project

cross section graphic of earth layers showing groundwater table, source: USGS
Cross-section of groundwater shows how it is vulnerable to pollution that occurs on the land surface. Image source: USGS

The Washington Nitrate Prioritization Project is a compilation of groundwater data we published in May 2016 that identifies groundwater areas in Washington that are most vulnerable to nitrate contamination.

The information is not new, however what’s new is that we have compiled the groundwater data into one location. We have also prioritized the areas most susceptible to nitrate contamination. Previously, this data could only be found by searching a number of sources.

The goal of this project is to help the public – as well as local and state health officials and government decision-makers – be better informed about risk. Having access to this data in one location supports our efforts to protect problem areas.

Agencies contributing to the report, along with ourselves, included the Washington Departments Health and Agriculture, as well as the U.S. Environmental Protection Agency, U.S. Natural Resource Conservation Service, U.S. Geological Survey, and the Washington Conservation Commission.

If you have technical comments, please contact Laurie Morgan at Laurie.Morgan@ecy.wa.gov or 360-407-6483.

Why this matters

small map of high nitrate wells in Washington

Washington Nitrate Prioritization
Project story map

Nitrate contamination is a concern because groundwater is a source of drinking water for many people. Nitrate contaminated drinking water can harm the health of babies and lead to “blue baby” syndrome, which is a decreased ability of the blood to carry oxygen.

Nitrates can get into groundwater from many sources, including fertilizers, manure on the land, and liquid waste discharged from septic tanks. Natural bacteria in soil can convert various forms of nitrogen into nitrate. Nitrates are a good fertilizer for crops and plants, but when there is more fertilizer than they can use, rain or irrigation water can carry nitrate down through the soil into groundwater.

Washington state is seeing a rise in groundwater nitrate contamination as our use of fertilizer, manure production, and population have increased.

Both public water supply wells and individual residential wells have been contaminated in some areas of the state. Among others, these include the Sumas-Blaine Aquifer in Whatcom County, the Lower Yakima Valley and the Columbia Basin. Millions of dollars have been spent to deal with nitrate contamination of groundwater. Once aquifers are contaminated, it is difficult for them to recover.

Read the Washington Nitrate Prioritization Project report

For more information, please read the Department of Health Office of Drinking Water factsheet Nitrate in Drinking Water and the Northwest Pediatric Environmental Health Specialty Units factsheet Nitrates, Blue Baby Syndrome, and Drinking Water: A Factsheet for Families.

Contact us for more information


Last updated June 2016