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Fact Sheet 94-029

**U.S. GEOLOGICAL SURVEY  Fact Sheet 94-029**

# National Water-Quality Assessment Program   The Sacramento River Basin

**By Joseph Domagalski and Larry R. Brown**

In 1991, the U.S. Geological Survey (USGS) began to implement a full-scale   National Water-Quality Assessment (NAWQA) program. The long-term goals of the   NAWQA program are to describe the status of and trends in the quality of a   large, representative part of the Nation's surface- and ground-water resources   and to identify the major natural and human factors that affect the quality of   those resources. In addressing these goals, the program will provide a wealth of   water- quality information that will be useful to policy makers and managers at   the national, State, and local levels.

A major asset of the NAWQA program is that it will allow for the integration   of water-quality information collected at several scales. A major component of   the program is the study-unit investigation-the foundation of national- level   assessment. The 60 study units of the NAWQA program are hydrologic systems that   include parts of most major river basins and aquifer systems of the conterminous   United States. These study units cover areas of 1,000 to more than 60,000 square   miles and represent 60 to 70 percent of the Nation's water use and population   served by public water supplies. Investigations of the first 20 study units   began in 1991. In 1994, the Sacramento River Basin was among the second set of   20 NAWQA study units selected for investigation.Study Unit Description
The Sacramento River Basin covers nearly 27,000 square miles. The study unit   includes all or parts of five physiographic provinces: the Sacramento Valley,   the Sierra Nevada, the Coast Ranges, the Cascade Range, and the Modoc Plateau.   The Sacramento River is the largest river in California, with an average annual   runoff of 22,000,000 acre-feet. This is approximately one third of the total   runoff in the State. The length of the Sacramento River is 327 miles. The river   is vital to the State's economy and is a major source of drinking water for   residents of northern and southern California. The Sacramento River is a   principal source of irrigation water for Sacramento and San Joaquin Valley   farmers and freshwater flow to the San Francisco Bay.

Water use in the study unit was 11.6 million acre-feet in 1990, and this   amount is expected to rise to 12.4 million acre-feet by the year 2020. Water use   in 1990 was 58-percent agricultural, 32-percent environmental, 6-percent urban,   and 4-percent other. Up to about 6 million acre-feet per year of water also is   exported from the basin, principally to areas in southern California, by local,   State, and Federal conveyance facilities. The flows of the Sacramento River are   controlled mainly by Shasta Dam and, to a lesser extent, by dams on the Feather,   Yuba, and American Rivers. Part of the runoff from winter rains and spring   snowmelt is stored in reservoirs and released during the normally dry summer   months. Most of the water supplies are derived from these reservoirs.

The Sacramento Valley is a major ground-water basin and can be considered a   single-aquifer system. The storage capacity of the Sacramento Valley   ground-water basin is about 114 million acre-feet at depths of 20 to 600 feet   below land surface. Ground water provides about 22 percent of the water supply   and is used extensively as a source of drinking and irrigation water,   particularly in areas removed from surface-water supplies.

The Sacramento Valley supports a diverse agricultural economy, much of which   depends on the availability of irrigation water. More than 2 million acres are   irrigated. Major crops include rice, fruits and nuts, tomatoes, sugar beets,   corn, alfalfa, and wheat. Dairy products are also an important agricultural   commodity. In the study unit, the Sacramento Valley has the largest cities,   including Chico, Red Bluff, Redding, and Sacramento. The Sacramento metropolitan   area is home to more than 1 million people, which is nearly half of the total   population of 2,208,900 people, in the study unit. The population in the study   unit increased by more than a one-half million people between 1980 and 1990.   Land cover within the Sierra Nevada and Cascades Range is principally forest.   Forest and range land are mixed throughout the Coast Ranges and Modoc Plateau.

The Sacramento River Basin contains a number of species, subspecies, and   genetically distinct populations of fish that are presently listed as Federal or   State threatened/endangered species or species that appear to be approaching   that status. The winter-run race of chinook salmon (Oncorhynchus tschawytscha)   that spawn below Keswick Dam in the mainstem Sacramento River is on the Federal   list of endangered species. The spring-run chinook salmon that spend the summer   in deep, cool pools of streams tributary to the Sacramento River before spawning   in the early fall are presently a species of special concern, and efforts are   being made to increase its population before the species becomes endangered. The   Sacramento splittail, Pogonichthys macrolepidotus, a large minnow native to the   Sacramento-San Joaquin drainage and the only remaining representative of the   genus in the world, has been officially proposed as a threatened species by the   U.S. Fish and Wildlife Service.
Major Water-Quality Issues
The NAWQA study will focus on the quality of   ground-water and surface-water resources in the Sacramento Valley, because most   of the population, agriculture, and water use are in that part of the study   unit. Information for the other physiographic provinces will be used primarily   to establish background water- quality conditions or to establish loadings of   key water-quality constituents. The major water-quality issues of concern in the   Sacramento River Basin study unit are:
- Elevated concentrations of trace metals, especially from abandoned     mines --A number of abandoned mines, especially those near Lake Shasta have     the potential to degrade the quality of much of the Sacramento River.
- Pesticide contamination of surface water and potential contamination of     ground water --Pesticide use within the Sacramento Valley is high and     occurs during as much as 75 percent of each calendar year. Pesticides can be     transported from the fields to surface water by irrigation and storm runoff or     to ground water by percolation of rain or irrigation water.
- Nitrate contamination of ground water --Ground water in localized     areas, particularly those with highly permeable soils, is susceptible to     contamination by nitrate from fertilizers and other sources.
- Urban runoff and volatile-organic- chemical contamination --Urban     runoff from the metropolitan area of Sacramento is a potential source of     contaminants that enter the lower Sacramento River. Contamination by volatile     organic compounds, especially contamination of ground water, can occur in any     large urban setting.
- Issues considered important for aquatic species include the operation of     dams and diversions of all sizes and their effects on streamflow, aquatic     habitat, fish migration, and stream temperature. Other issues affecting     aquatic species include acidic mine discharge, agricultural return flows,     reductions in fish populations by commercial and sport fishing, and     introduction of non-native species. 
Communication and Coordination
Communication and coordination between   USGS personnel and other interested scientists, water-management organizations,   and public and private interest groups are critical components of the NAWQA   program. Each of the study units will have a liaison committee consisting of   representatives from Federal, State, and local agencies, universities,   environmental groups, and the private sector who have water-resources   responsibilities. Specific activities of each liaison committee will include the   exchange of information about water-quality issues of regional and local   interest; the identification of sources of data and information; assistance in   the design and scope of project products; and the review of project-planning   documents and reports. The liaison committee for the Sacramento River Basin   study unit will be formed in 1994.

***Joseph Domagalski******Larry R. Brown***
Information on technical reports and hydrologic data   related to the NAWQA program can be obtained from: 
***Project Chief--Sacramento River Basin NAWQA Study***U.S. Geological SurveyPlacer Hall, Bldg. 56          6000 J StreetSacramento, California 95819-6129E-mail: mailto:joedusgs.gov

USGS Sacramento River Basin NAWQA USGS HeadquartersUSGS Water Resources of CaliforniaUSGS National Water Quality Assessment (NAWQA) Program 

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U.S. Department of the Interior | U.S. Geological Survey    URL: http://pubs.usgs.gov/fs/1994/fs94029    Page Contact Information: Publications Team    Page Last Modified:    Wednesday, 30-Apr-2008 14:22:40 EDT