Water Quality Improvement Projects (TMDLs) >
WRIAs 37,
38,
39 > Yakima River
Basin Area Projects
Water Quality Improvement Projects
Yakima River Basin
Area
Introduction
The Yakima River originates in Kittitas County, Washington State, from
the Keechelus and Kachess Lakes on the east side of the Cascade Mountains
near Snoqualmie Pass. The river flows over two hundred miles, heading southeast through the
Kittitas and Yakima valleys, then discharges into the Columbia
River near Richland. Tributaries include the Cle Elum, Teanaway, and
Naches rivers, as well as numerous creeks and irrigation returns. The
confluence of the Yakima and Naches Rivers at the city of Yakima divides
the Yakima River into "upper" and "lower" portions. About one-half of the Yakima Basin
(Basin) is within and occupies most of
Yakima County. The upper part of the Basin lies in Kittitas County and
occupies most of that county. The southeastern part of the Basin
occupies about one-half of Benton County, and the southern part of the
Basin extends slightly into Klickitat County. The entire Basin lies within areas either ceded to the United States
by the Yakama Nation or areas reserved for the use of the Yakama Nation.
The Yakama Reservation occupies about 40 percent of Yakima County and
about 15 percent of the Basin. Along with its tributaries, the river
system drains about 6,150 square miles or 4 million acres.
Average annual precipitation ranges in the Yakima Basin vary from 91
inches annually at Snoqualmie Pass (at the headwaters of the Yakima River in the
Cascade Range) to 7.9 inches annually in the city of Yakima. Most of the water
in the Yakima River comes from snowmelt, and is caught in a series of reservoirs
to ensure a sufficient water supply throughout the irrigation season. Much
of the water is diverted for irrigation in the Yakima Valley, but some is
recovered through surface and subsurface routes. From
50 to 100 percent of the water delivered to the lower basin from the Naches River and
upper Yakima River is diverted for irrigation and hydropower generation during
the irrigation season.
Land use in the Basin includes nearly 40 percent forested, 40 percent
rangeland, 15 percent cropland, and the remaining acreage in other land
uses. Irrigated agriculture, the main economy of the Basin, occupies about
1,000 square miles. Cattle grazing is the main use of 2,900 square miles
of rangeland. Timber harvest, cattle grazing, and recreation are the
major uses of the 2,200 square miles in the forested areas of the Basin
to the north and west. About one-fourth of the forested area is
designated as wilderness.
Water quality issues
Water quality issues in the Basin range from fecal coliform bacteria to
suspended sediments and turbidity, as well as toxics and temperature. Please
see the state's water quality
assessment for a list Yakima River water quality issues.
Why this matters
The water quality issues in the Basin impact the
beneficial uses of the water, potentially making it unsafe for drinking or
recreation and threatening the health of aquatic animals and fish living in
it.
What is being done
There are a number of water quality improvement projects, mainly in the
form of total maximum daily loads (TMDLs), in various stages of development
across the watershed. Please use the links below to get more information on
a project.
Project information
Related information
WRIA 37: Lower Yakima Watershed Information (Environmental Assessment
Program web site)
www.ecy.wa.gov/apps/watersheds/wriapages/37.html
WRIA 38: Naches Watershed Information (Environmental Assessment
Program web site)
www.ecy.wa.gov/apps/watersheds/wriapages/38.html
WRIA 39: Upper Yakima Watershed Information (Environmental Assessment
Program web site)
www.ecy.wa.gov/apps/watersheds/wriapages/39.html
Contact us for more information
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