Southern Willamette Valley Groundwater Management Area

The Southern Willamette Valley Groundwater Management Area (GWMA) was declared in 2004 because of high nitrate contamination in a 230 square mile area of the Willamette Valley. A multi-year, multi-stakeholder process is addressing the nitrate contamination issue.   The GWMA encompasses portions of Lane, Linn, and Benton counties and includes five cities (Corvallis, Harrisburg, Monroe, Junction City, and Coburg).   Scientific studies have found nitrate to be associated with methemoglobinemia (blue baby syndrome), diabetes, negative reproductive outcomes, and various forms of cancer.  Public water suppliers must test their water regularly but rural home owners are not required to do so and are often unaware of contamination issues.

Extensive testing in 2000-02 by the Department of Environmental Quality concluded that nitrate was a contaminant of concern in groundwater in the Southern Willamette Valley.  Nitrate was found at greater than 7 mg/L in more than 20% of samples analyzed in 2000 and 2001.  Those with high levels were re-sampled in 2002 and more than 90% of those samples were still above 7mg/L. Nitrate was found at many locations at concentrations greater than the public drinking water standard (10 mg/L) and at more than three times the standard in several locations. DEQ now monitors the GWMA groundwater quality quarterly by sampling at 41 well locations. Our pollutant load reduction target is to reduce all nitrate levels in the groundwater to less than 7mg/L.  

• March 29, 2011  EPA Webinar on the SWVGWMA.

• SWVGWMA project presentation at a National Groundwater Summit in Denver Colorado in 2010.

• GWMA Committee Meetings

•  SWVGWMA Nitrogen Nitrate Budget

• Official documents and reports

• Schedule of upcoming events

• GWMA Committee and Sub-Committee Meeting Archives

• Research reports and graduate student theses

• Media associated to the SWVGWMA

• Contact information for everyone involved in the project

• July 2008 GWMA Tour video!

The GWMA Action Plan

The Southern Willamette Groundwater Management Area Action Plan (PDF-3.6MB) was approved by the Groundwater Management Area Committee on November 9, 2006. See the Action Plan page for more details.

• Map of the GWMA

• Declaration fact sheet

• Background information.

Agency Staff, the GMWA Committee & Working Groups

Staff from DEQ, Lane Council of Governments (LCOG), Oregon Department of Agriculture (ODA), and Oregon State University Extension Service (OSU Ext) have responsibility for different aspects of the GWMA project. A Groundwater Management Area Committee was appointed by DEQ to work with staff in the development of a strategic plan to protect and improve the quality for groundwater within the GWMA. Members of the GWMA Committee represent different groups who could have an impact on groundwater or who may be impacted by its contamination. Each of the four responsible agencies led a working group: Commercial & Industrial (DEQ); Public Drinking Water (LCOG); Agricultural (ODA); and Residential (OSU Ext). The working groups were composed of a few GWMA Committee members, staff from multiple state and local agencies, and other interested parties.