Lower Yakima Valley Groundwater | Region 10 | US EPA

Jump to main content.


Lower Yakima Valley Groundwater

Questions? ¿Preguntas?
  • Contact Marie Jennings (jennings.marie@epa.gov)
    800-424-4372, ext. 1893 or 206-553-1893
  • Para espanol, póngase en contacto con Rochelle Labiosa (labiosa.rochelle@epa.gov)
    800-424-4372, extensión 1172 o 206-553-1172
Sign up for email updates about this project:
Why is Nitrate a Concern?

Nitrate is an "acute contaminant" meaning that one exposure can affect a person's health. Too much nitrate in your body makes it harder for red blood cells to carry oxygen.

Most people recover quickly after being exposed to nitrate, but it can be very dangerous for infants and some adults. Infants exposed to high amounts of nitrate may develop a potentially fatal condition known as "blue baby syndrome."

EPA's drinking water standard - or “maximum contaminant level” (MCL) - for nitrate is 10 mg/L (parts per million, or ppm). Unlike many other substances for which a standard has been set by EPA, there is no “safety factor” built into the nitrate MCL.

Learn more

Groundwater Management Area (GWMA)

EPA is also working with the Lower Yakima Valley Groundwater Management Area advisory committee to develop a comprehensive plan to reduce nitrate contamination in groundwater to below drinking water standards.

About this project

Local, state, and federal agencies, including EPA, are working with dairies in Washington's Lower Yakima Valley to address sources of nitrate contamination in groundwater. Read more project history

Administrative Order on Consent (Consent Order)

In March 2013, EPA and several dairies in the Lower Yakima Valley area signed the following legal agreement called a Consent Order to address sources of nitrate contamination in groundwater near and downgradient of the dairies’ facilities.

In signing the Consent Order the dairies agreed to:

  1. Provide an alternate source of drinking water for neighbors within one mile down gradient of the dairies whose wells have levels of nitrate above EPA’s drinking water standard of 10 mg/L, or “parts per million” (ppm).
  2. Conduct soil and groundwater testing at each dairy to evaluate if nitrogen sources are being controlled.
  3. Take steps to control nitrogen sources (manure and commercial fertilizer) at their facilities.
Plans, reports, and monitoring under the Consent Order

Key documents that have been completed under the Consent Order so far are posted below:

Residential wells (links to EPA file sharing site)

  • Final Residential Well Report
  • Residential Well QAPP

Irrigation Water Management Plans (not yet available)

Application Field Management Plans (links to EPA file sharing site)

  • Cow Palace
  • George DeRuyter & Son Dairy, and D&A Dairy
  • Liberty Dairy, and Henry Bosma Dairy

Groundwater Monitoring (links to EPA file sharing site)

  • Groundwater Monitoring Well Quality Assurance Project Plan
  • Groundwater Monitoring Well Installation Report (not yet available)
  • First Annual Groundwater Monitoring Report (not yet available)

Lagoon Assessments (links to EPA file sharing site)

  • Cow Palace
  • George DeRuyter & Son Dairy, D&A Dairy
  • Liberty Dairy, Henry Bosma Dairy

Lagoon Evaluation Plans (not yet available)

Monitoring Well DC-03 Investigation (not yet available)

Backflow Prevention Reports (links to EPA file sharing site)

  • Cow Palace
  • George DeRuyter & Son Dairy, D&A Dairy
  • Liberty Dairy, Henry Bosma Dairy

Monthly Progress Reports (links to EPA file sharing site)

Eight Year Report (due March 2021)

After eight years of quarterly groundwater sampling, the dairies will summarize all of the groundwater data collected over the eight years. If, after eight years of monitoring there is no downward trend in one or more downgradient wells that exceed the nitrate drinking water standard, considering the upgradient well data, or the wells that were below the drinking water standard show increasing nitrate levels, then the dairies will undertake additional source control actions in the vicinity of those wells.

Other documents

Technical background documents

Site assessment documents

Public input

EPA provided an opportunity for public input on the 2012 report from September 27, 2012 to November 30, 2012. We received input from 43 individuals or organizations.

Fact sheets

Project history

Responding to community concerns in Washington’s Lower Yakima Valley about high nitrate levels in residential drinking water wells and the potential for disproportionate impacts on low income and minority rural populations, local, state, and federal agencies collaborated to develop a Preliminary Assessment and recommendations for moving forward (see site assessment documents).

One of the recommendations was to develop new projects that could help to identify sources of the contamination in groundwater supplies.

In accordance with this recommendation, EPA conducted sampling in 2010 as part of a study to identify potential sources of nitrate contamination in local groundwater and residential drinking water wells. EPA issued a report in March 2013 entitled, Relation Between Nitrate in Water Wells and Potential Sources in the Lower Yakima Valley. The study concluded that several dairies in the report were likely sources of elevated nitrate levels that were measured in residential drinking water wells downgradient of the dairies.

In December 2012 and January 2013 EPA installed and sampled 10 groundwater monitoring wells in the vicinity of the Yakima Valley dairies that were included in the 2010 study. Data collected by EPA from the monitoring wells confirmed that that the dairies are a source of nitrate contamination to the groundwater beneath and downgradient of these dairies. More recent and extensive data collected by the dairies under the Consent Order affirm this conclusion.


Local Navigation


URL: http://yosemite.epa.gov/r10/water.nsf/GWPU/lyakimagw

Jump to main content.