Groundwater in the Yakima River Basin, Washington

Problem and Needs

At the onset of the study, the following needs were identified:

The surface water in the Yakima River Basin is under adjudication, and it is not known how much is available for appropriation. There are increasing demands for water for municipal, fisheries, agricultural, industrial, and recreational uses, which must be met by groundwater withdrawals and/or by changes in the way water resources are allocated and used. Ongoing activities in the basin to enhance fisheries and to obtain additional water for agriculture may be affected by groundwater withdrawals and by rules implemented under the Endangered Species Act for salmonid fish. An integrated understanding of the groundwater and its relation to the surface-water resources is needed to implement most water-resources management strategies in the basin.

Objectives

The objectives of the study were to:

1. Describe the groundwater flow system and its interaction with surface water, to improve conceptual understanding of the system, and to guide and support actions taken by natural-resource management agencies.
2. Integrate hydrogeologic information into a numerical groundwater model. The model functions as an integrated tool for daily to long-term water-resources management and for testing potential management strategies

Relevance and Benefits

The study addressed many issues identified in the USGS Water Resources Division's strategic plan for meeting the Nation's water resources needs. They include the development of tools for managing the Nation's watersheds effectively and the improvement of existing simulation tools. Other important issues include the assessment of availability and sustainability of America's water, estimating effects of land-use and management alternatives on water quantity, and determining effects of groundwater withdrawals on surface water and aquatic ecology. The USGS is a neutral scientific party that provides information and develops models to solve important problems that are common in the Nation.

Approach 

The study was conducted in three phases. 

Phase 1: Planning and assessment

• Project planning and coordination.
• Gathering, compiling, documenting, and assessing available data.
• Collecting initial data. 

Phase 2: Data collection 

• Mapping of hydrogeologic units.
• Estimating ground-water use.
• Developing estimates of groundwater recharge.
• Constructing maps of groundwater levels. 

Together, these four work elements provide the information for an overall description of the groundwater flow system and the building blocks for the hydrogeologic framework. 

Phase 3: Develop a groundwater flow model

Integrate available information into a groundwater flow model.

Outcomes

The numerical groundwater model provides an understanding of the flow system and its relation to surface water, and can be used to inform management strategies. 

A complete list of data and reports associated with this project may be found under the Publications tab.