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:

We used many scientific studies and their data to develop the program documents.  Many of them are linked in the accordion below for reference. 

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.

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.