Lower Yakima Valley Groundwater Management Area

We're partnering in a local effort to reduce nitrate concentrations in Lower Yakima Valley private drinking water wells.

En Español

The Lower Yakima Valley Groundwater Management Area (GWMA) is a community-based effort working to reduce nitrate concentrations where many residents rely on groundwater as their drinking water source. We have worked with the advisory committee to complete a comprehensive groundwater management program. 

The goal of the program is to address all sources of nitrate, and implement strategies to improve groundwater quality to meet drinking water standards.

Lower Yakima valley groundwater management program

The Groundwater Management Area Program development was led by Yakima County and guided by an advisory committee of residents, stakeholders, and affected government entities. The program was finalized and submitted by consensus with a request for Ecology certification on June 20, 2019.

We will continue to work with the community to implement this plan to reduce nitrates in the groundwater. See our Frequently Asked Questions for more information about the program development process. 

Program documents:

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.

Solutions led by the community

In 2011, the Legislature authorized funding for Yakima County to establish the Lower Yakima Valley Groundwater Management Area in accordance with state statute to develop strategies to reduce groundwater contamination in the Lower Yakima Valley. Initial studies showed 12 percent of private domestic wells had elevated concentrations of nitrate in the Lower Yakima Valley.

Led by Yakima County, an advisory committee formed and guided the development of a comprehensive groundwater management program. The committee is made up of concerned residents, environmentalists, farmers, dairy producers, university, tribal, as well as local, state, and federal government agencies. We worked with the committee to finalize the plan to address nitrate contamination and certified it on July 29, 2019. We will continue to work with the advisory committee by administering the program and reduce nitrate contamination where concentrations do not meet drinking water standards.

Ongoing sampling and data 

Studies show that fertilizer applications and current land-use activities are contributing to the nitrate-loading on land and in aquifers.

We are working with partners to provide research, data, and technical support. The most recent efforts include a 2017 sampling effort within GWMA boundaries that tested more than 150 private domestic wells. Also, in 2019 an Ambient Well Monitoring System was installed. The Monitoring System consists of 30 monitoring locations throughout the groundwater management area that will be used to evaluate progress during implementation of the program. 

There are more resources on the Yakima County Lower Yakima Valley Groundwater Management Area website.

Why it matters

Nitrates are a concern in the Lower Yakima Valley — especially in areas where many homes draw drinking water from shallow aquifers. Nitrate levels exceed state drinking water standards in some regions of the valley. In other areas, concentrations are high enough to show us the community needs to avoid introducing nitrogen to their groundwater system to protect the quality of their drinking water.

Nitrates can be a risk to your health

Drinking water high in nitrates poses a threat to children under age five, infants, pregnant mothers, and the elderly. It can lead to a serious condition that reduces oxygen to red blood cells, which may cause death if untreated. 

How do nitrates get into the environment?

Agriculture is the primary economic and land use activity in the Lower Yakima Valley. Agriculture lands — such as irrigated row crops, orchards, large and small livestock, and dairy operations — can be a source of nitrate pollution if they are not managed properly

Studies show that various land-use activities along with agricultural activities are contributing to the nitrate-loading on land and in aquifers.The Lower Yakima Valley GWMA is working across the region to educate landowners and identify which best farming practices protect water quality. Learn more about our effort to develop best management practices (BMPs) for agriculture.