By Jo Ann M. Gronberg, Neil M. Dubrovsky, Charles R. Kratzer, Joseph L. Domagalski, Larry R. Brown, and Karen R. Burow

U.S. Geological Survey Water-Resources Investigations Report 97-4205

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Complete report available as a PDF document (4.4 MB). Download Acrobat reader
 

Abstract
The National Water Quality Assessment Program for the San Joaquin-Tulare Basins began in 1991 to study the effects of natural and anthropogenic influences on the quality of ground water, surface water, biology, and ecology. The San Joaquin-Tulare Basins study unit, which covers approximately 31,200 square miles in central California, is made up of the San Joaquin Valley, the eastern slope of the Coast Ranges to the west, and the western slope of the Sierra Nevada to the east. The sediments of the San Joaquin Valley can be divided into alluvial fans and basin deposits.
 

The San Joaquin River receives water from tributaries draining the Sierra Nevada and Coast Ranges, and except for streams discharging directly to the Sacramento-San Joaquin Delta, is the only surface-water outlet from the study unit. The surface-water hydrology of the San Joaquin-Tulare Basins study unit has been significantly modified by development of water resources. Almost every major river entering the valley from the Sierra Nevada has one or more reservoirs. Almost every tributary and drainage into the San Joaquin River has been altered by a network of canals, drains, and wasteways.
 

The Sierra Nevada is predominantly forested, and the Coast Ranges and the foothills of the Sierra Nevada are predominately rangeland. The San Joaquin Valley is dominated by agriculture, which utilized approximately 14.7 million acre-feet of water and 597 million pounds active ingredient of nitrogen and phosphorus fertilizers in 1990, and 88 million pounds active ingredient of pesticides in 1991. In addition, the livestock industry contributed 318 million pounds active ingredient of nitrogen and phosphorus from manure in 1987.

 
The report provides the background information to assess the influence of these and other factors on water quality and to provide the foundation for the design and interpretation of all spatial data. These characterizations provide a basis for comparing the influences of human activities among basins and specific land use settings, as well as within and among study units at the national level.

 
Contents
Abstract
The National Water-Quality Assessment Program
San Joaquin-Tulare Basins
    Location and Physiography
    Geology
    Climate
    Natural Hydrology and Native Habitats
    Ecology
        Ecoregions
        Aquatic Biology
    Surface-Water Hydrology
        Distribution Systems
        Major Reservoirs
        Annual Discharge
        Seasonal Discharge
        Water Storage and Availability
    Ground-Water Hydrology
        Regional Ground-Water Flow System
        Predevelopment Ground-Water-Flow
        Ground-Water Development and Response
Factors Affecting Water Quality
    Land Use
        AGricultural Land Use
        Urban Land Use
    Water Use
    Point Sources
    Agricultural Sources
        Discharges to the San Joaquin River
        Pesticides
        Nutrients from Fertilizers
        Nutrients from Manure
Major Water-Quality Issues
Summary
References Cited