Central Columbia Plateau - Yakima River Basin


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Basin Description

The Central Columbia Plateau/Yakima River Basin (CCYK) National Water-Quality Assessment (NAWQA) study unit is located in Central Washington, USA. The study unit is dominated by intensive agricultural practices, with irrigated agriculture a common practice for crop production (see study area description). Due to the intensive agriculture and irrigation, this area exhibits a number of water quality issues including high nutrient loading resulting in eutrophication, elevated concentrations of water soluble pesticides, and elevated concentrations of organochlorine compounds (e.g. DDT) in both bed sediment and fish. Given the overriding presence of agriculture and the documented effects of agricultural practices, continued work in the study unit will focus on separating out the mechanisms and effects of various agricultural management practices on ground water, surface water and stream ecosystem conditions to truly understand how natural and anthropogenic chemicals move through the hydrologic system. This information should dramatically help local, regional, state, and federal land managers produce fair and sound decisions regarding water and land management within the CCYK study area.

Central Columbia Plateau / Yakima River Basin Study Approach

During Cycle I of NAWQA, most of the work within the CCYK study unit focused on assessing the status and trends in the quality of freshwater streams and aquifers, and to provide a sound understanding of the natural and human factors that affect the quality of these resources (see Publications).

During Cycle II, most of the program's effort will be on examining water quality trends, understanding the mechanisms by which contaminants move through hydrologic systems and characterizing the potential effects of contaminants and other water-quality disturbances on humans and aquatic ecosystems. To describe water quality trends, previous surface water and groundwater sites will be re-examined to characterize decadal changes. To understand the mechanisms affecting the transport of contaminants through the hydrologic system and their potential impacts within the study unit, two topical studies will be performed (see Scientific Topics). These topical studies will include the Agricultural Chemical Transport Study (ACTS) designed to understand the transport of agricultural chemicals through the groundwater and surface water and the Nutrient Enrichment Effects (NEET) study designed to examine the response of aquatic biota to varying levels of nutrients as a result of natural and management conditions. The majority of this work will be conducted between 2002 and 2005.

The National Water-Quality Assessment Program

Since 1991, USGS scientists with the NAWQA program have been collecting and analyzing data and information in more than 50 major river basins and aquifers across the Nation. The goal is to develop long-term consistent and comparable information on streams, ground water, and aquatic ecosystems to support sound management and policy decisions. The NAWQA program is designed to answer these questions: 1. What is the condition of our Nation's streams and ground water? 2. How are these conditions changing over time? 3. How do natural features and human activities affect these conditions?