OREGON: Southern Willamette Valley
Groundwater Management Area
A Regional, Multi-jurisdictional Approach to
Groundwater Protection
Background
The Oregon Department of Environmental Quality declared a Groundwater Management
Area for a portion of the Southern Willamette Valley because of high nitrate. The 230
square mile area includes five cities, and portions of three counties with multiple land
uses. A stakeholder group known as the Groundwater Management Area Committee,
incorporated about 60 strategy recommendations into an Action Plan, which propose
voluntary actions to address potential risks to the groundwater resource. Rather than
focusing solely on nitrate, the Committee also took advantage of the recently completed
Source Water Assessments and incorporated strategies to reduce other potential risks to
the 50 public water systems within the same area. The Committee focused on common
high and medium risks within the 5 year time of travel.
Location: A 230 square mile region, including three counties and five cities within the
Southern Willamette Valley, Oregon, with a population of about 23,000.
Water Supply: There are 52 public water systems, with all but one being sole source
ground water systems. There are 37 larger systems (serving at least 25 people or 15
connections) and 15 smaller state regulated systems. The 9,000 rural residents rely on
domestic wells for their water supply.
Source Water Assessment: Multiple studies indicate high (>7 mg/L) nitrate levels in the
ground water throughout the area. The area was declared a Groundwater Management
Area in 2004 because of high nitrate levels throughout the region. Fifteen public water
systems have tested positive for nitrate levels greater than 7 mg/L in the past five years.
• Combined data from the Source Water Assessments of the public water systems
indicate that there are about 40 different types of potential contaminant sources
with about 75 percent of those considered a high or medium risk.
• The most common potential contaminant sources include agriculture (irrigated
and non-irritated, heavily used transportation corridors, large onsite septic
systems, wells/abandoned wells, and high-density housing. Other risks include
hazardous waste spills, vehicle and equipment repair facilities, fuel and/or
chemical storage tanks, and a variety of commercial enterprises.
Priority Contamination Threats
Both surface and ground water quality in the region is threatened by agricultural
activities and unplanned development.
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• Priority threats of nitrogen/nitrate come from fertilizer use, high density
development using septic systems, animal waste from confined feeding
operations or small farm livestock, and large permitted onsite wastewater
treatment facilities.
• Contamination threats that are high or moderate in risk and are closest to the
wells (within 5-year time of travel zones) are priorities and include agricultural
practices, major roadways, large onsite septic systems, wells/abandoned wells,
and high-density housing.
Local Team and Developing the Protection Plan
A stakeholder group known as the Groundwater Management Area Committee
developed an Action Plan, which includes 60 voluntary strategies to address potential
risks to the ground water resource. The stakeholder group, appointed by the Oregon
Department of Environmental Quality (DEQ), is comprised of a cross-section of principle
land use sectors in the region, and includes realtors, farmers, public works staff, county
commissioners, a small city mayor, residents, representatives of small and large
businesses, an engineering firm, among several others. Rather than focus solely on
nitrate, the known contaminant in the region, the Committee also took advantage of
Source Water Assessments and addressed other "potential" contaminant risks to public
water supplies.
The core staff coordination team is comprised of Lane Council of Governments, DEQ,
Oregon State University Extension Service and Oregon Department of Agriculture
(ODA). The DEQ is the lead agency responsible for project oversight, Lane Council of
Governments brings strong regional coordination skills combined with GIS expertise,
OSU Extension has extensive contact and rapport with rural residents and ODA leads
the agricultural portion of the work. About 20 other partners are also fully engaged
providing technical and planning expertise as needed. These include city and county
staff and public officials; the Departments of Human Services, Water Resources, and
Land Conservation and Development; watershed councils; the Rural Community
Assistance Corporation and public water system operators.
Protection Measures
This project is to reduce contributions of nitrate to ground water and to prevent other
potential contaminants from reaching the water supply. To reach this end, community
based, voluntary mechanisms have been identified and can be categorized in the
following ways:
• Outreach and Education: Getting the word out about ground water contamination
issues, and what can be done by all land users to reduce contamination risk.
• Incentives: Encouraging ground water protection and offsetting potential
financial burdens.
• Technical Assistance: Linking technical experts with residents, farmers, local
government leaders, and business owners.
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• Planning Tools: Land use considerations that could be implemented to protect
and restore ground water quality.
• Research: Measuring the effectiveness of methods to protect ground water
quality.
• Monitoring: Implementing a ground water monitoring network that will allow an
assessment of the improvement of ground water quality.
Program Effectiveness
In 2010 a formal review of project progress and effectiveness will be conducted
providing an assessment using a three pronged measurement:
• Action Plan Strategy Implementation: This measurement tracks the number of
strategies in the Action Plan, implemented over time. Twice a year, staff compiles
a list of activities that have been performed during the last 6 month period. The
GWMA Committee reviews the activities and provides direction for future strategy
implementation. The "nitrogen/nitrate budget" completed in 2008, provides an
estimation of the amount of nitrogen/nitrate contributions by land use. This
budget can forecast contaminant reductions that result from behavior and land
use changes and then can measure the actual changes in nitrogen/nitrate
contributions as strategies are implemented and land use practices change.
• Public Awareness and Understanding: Currently a survey is being distributed for
baseline measurement of resident's awareness and understanding of the
GWMA. A follow-up survey will be conducted every 3-5 years to measure
changes in that understanding and awareness.
• Groundwater Quality Monitoring: The target load reduction is to bring nitrate
levels below 7mg/L Groundwater quality monitoring that will ultimately measure
the effectiveness of the Action Plan includes:
• Baseline and Long-Term Methodology - In 2006, the DEQ began
sampling at 40 quasi-randomly selected, distinct, and consistent locations
to create a baseline to measure future results against. Samples from
these locations are collected and lab analyzed quarterly establishing a
solid baseline. The monitoring network of 25 monitoring wells and 15
domestic wells will continue to be used to quantify changes in
groundwater quality.
• Supplemental Monitoring Data - The Voluntary Monitoring Network
includes 125 domestic wells. Residents are collecting and analyzing
these samples on a regular basis as determined by the neighborhood.
Contingency Planning
Three of the cities in the GWMA have individual Drinking Water Source Protection Plans
that include a contingency planning component. In addition nearly all of the 37 larger
public water systems have developed contingency plans that establish protocol in case
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of source contamination, emergency spill or other potential loss of water availability.
Several of the jurisdictions in the area have conducted mock exercises to help
coordinate and prepare for emergency contamination and/or water loss situations.
For further information, contact:
Denise Kalakay (541) 682-7415.
Senior Planner
Lane Council of Governments
99 East Broadway
Eugene, OR 97401
DKALAKAY@lcoq.org
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