Lower Yakima Valley Groundwater Management Area

We are working with partners to reduce nitrate concentrations in private drinking water wells in the Lower Yakima Valley. The goal of the community based effort is to implement strategies to reduce sources of nitrates, improve aquifers to meet drinking water standards, and educate residents about the problem and how they can protect themselves.

En Español

Effort to reduce nitrates in drinking water 

Nitrate sources can be from fertilizers on farms and at residences, livestock and dairy herds, irrigation, municipal and commercial applications.

The Lower Yakima Valley Groundwater Management Area (GWMA) was created to identify and reduce nitrates in an aquifer that provides drinking water for as many as 56,000 residents in the Lower Yakima Valley.

Studies estimate that 20% of private domestic wells in the Lower Yakima Valley may have elevated levels of nitrate. This is a public health issue for vulnerable populations – pregnant women, infants, elderly, and children under five.

Sources of nitrate include past and present agricultural practices, failing septic systems, residential and municipal fertilizers, irrigation, and commercial activities.

Learn more about how nitrates get into our enviroment in the Why it matters section below.

Working together for solutions

At the request of Yakima County, we designated the Lower Yakima Valley Groundwater Management Area boundaries and formed the Lower Yakima Valley Groundwater Management Area Advisory Committee comprised of county, local health, state and federal agencies, agricultural, residental, and environmental interests.

Led by Yakima County, our staff partnered with the committee to build a plan to address nitrate pollution from its various sources. Subcommittees looked at areas of concern including fertilizer, livestock and irrigation, and domestic, municipal and commercial sources, and conducted education and outreach throughout the process.  

In 2019, the Advisory Committee adopted recommendations and Ecology certified the program to implement strategies to improve groundwater quality to meet drinking water standards. Read more about the committee and the plan in the Program documents section below.

Our water quality staff and scientists continue to lend support to provide research, data, and technical expertise to help the community implement the plan.

Ongoing monitoring, sampling, and data gathering 

In the summer of 2021, we added 170 drinking water wells to our monitoring network as part of our committment to implement GWMA recommendations. Over the next several years, participants will receive test results and an explanation of what they mean. This information will help us to better understand the condition of the aquifers and where there are areas of concern in the Lower Yakima Valley Groundwater Management Area (see map).

Find more information about our study on our groundwater assessment webpage or visit the Lower Yakima Valley Groundwater Management Area partner website.

En Español

El Área de Manejo de Agua Subterránea del valle bajo de Yakima (GWMA) se formó en 2012 para abordar la meta de reducir la concentración de nitratos en el agua subterránea. El contenido del programa describe el problema de la elevación de los nitratos en el agua subterránea, cómo se estableció el programa GWMA en el valle bajo de Yakima y define las metas y objetivos desarrollados para el GWMA. Este informe explica los efectos ambientales y en la salud de los nitratos en el ambiente, describe los orígenes de nitrato, y las diferentes autoridades reguladoras que afectan el nitrato en el agua subterránea.