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Research about San Joaquin Valley

Source-linked reports with geographic coverage including San Joaquin Valley.

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USGS1973

Geology and quality of water in the Modesto-Merced area, San Joaquin Valley, California, with a brief section on hydrology

The Modesto-Merced area includes about 1,800 square miles on the northeast side of the San Joaquin Valley. The physiographic units in the area are (1) Sierra Nevada, (2) dissected uplands, (3) low alluvial plains and fans, (4) river flood plains and channels, and (5) overflow lands. Geologic units consist of consolidated rocks and unconsolidated deposits. The dominant structure of the geologic units is that of a homocline, which reflects the southwestward-tilted fault block of the Sierra Nevada. The consolidated rocks include: (1) basement complex (pre-Tertiary), (2) marine sandstone and shale (Cretaceous), (3) Ione Formation and other sedimentary rocks (Eocene), (4) Valley Springs Formation (late? Miocene), and (5) the Mehrten Formation (Miocene and Pliocene). In the eastern part of the area, the consolidated rocks generally yield small quantities of water to wells except for the Mehrten Formation which is an important aquifer. The unconsolidated deposits include: (1) continental deposits (Pliocene and Pleistocene?), (2) lacustrine and marsh deposits (Pleistocene), (3) older alluvium (Pleistocene and Holocene?), (4) younger alluvium (Holocene), and (5) flood-basin deposits (Holocene). The continental deposits and older alluvium are the main water-yielding units in the unconsolidated deposits. The lacustrine and marsh deposits (E-clay) and the flood-basin deposits yield little water to wells, and the younger alluvium in most places probably yields only moderate quantities of water to wells. There are three ground-water bodies in the Modesto-Merced area: (1) the unconfined water body, (2) the confined water body, and (3) the water body in consolidated rocks. The unconfined water body occurs in the unconsolidated deposits above and east of the E-clay, except in the western and southern parts of the area where clay lenses occur and semiconfined conditions exist. The confined water body occurs in the unconsolidated deposits below the E-clay and extends downward to the base of fresh water. The water body in consolidated rocks occurs under both perched and confined conditions. Ground-water movement in the unconfined and the confined water bodies is generally westward toward the valley trough. In the unconfined water body, the water also moves toward the major rivers, and toward pumping depressions at Modesto and near El Nido. Because of the higher head in the unconfined water body, water slowly moves from it through the E-clay to the underlying confined water body. Surface water is used extensively for irrigation in most of the study area; consequently, shallow water in the unconfined water body has to be controlled by pumping. Nevertheless, water levels near Modesto declined about 6 feet between 1958 and 1962, for the most part during the dry years 1959-61. Near El Nido, water levels declined about 70 feet between 1942 and 1967. In the confined water body, water levels were high in the winter and spring and low in the summer and fall, reflecting irrigation practices. In the southwestern part of the area, water levels in the confined water body declined about 14 feet from 1962 to 1968 and rose slightly after 1968, whereas in the northwestern part water levels remained fairly constant. Water from the upper reaches of the Stanislaus, Tuolumne, Merced, and Chowchilla Rivers is calcium bicarbonate in chemical type and is of excellent quality. As those rivers cross the valley floor, their water quality is generally degraded by return flows from irrigated land, and in the Tuolumne River by saline water discharged from abandoned gas wells. Average dissolvedsolids content in the major rivers, as indicated by chemical analyses, do not exceed 400 mg/1 (milligrams per liter) except in the San Joaquin River where average dissolved-solids content has not exceeded 1,050 mg/l. Water from minor streams in the area is bicarbonate in chemical type with dissolved-solids content ranging from 56 mg/1 to about 350 mg/l. Although chloride-type fresh ground water occurs in the unconfined and confined water bodies and in the water body in consolidated rocks, most of the fresh ground water is a bicarbonate type that has a dissolved-solids content of less than 500 mg/l. Water having dissolved solids in excess of about 2,000 mg/1 is considered to be saline. Saline water extends below the base of fresh water to the basement complex and, except in the extreme eastern part, underlies most of the study area. Saline water also occurs as lenses above the base of fresh water in the unconfined and confined water bodies.

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USGS1973

Geological literature on the San Joaquin Valley of California

The following list of references includes most of the geological literature on the San Joaquin Valley and vicinity in central California (see figure 1) published prior to January 1, 1973. The San Joaquin Valley comprises all or parts of 11 counties -- Alameda, Calaveras, Contra Costa, Fresno, Kern, Kings, Madera, Merced, San Joaquin, Stanislaus, and Tulare (figure 2). As a matter of convenient geographical classification the boundaries of the report area have been drawn along county lines, and to include San Benito and Santa Clara Counties on the west and Mariposa and Tuolumne Counties on the east. Therefore, this list of geological literature includes some publications on the Diablo and Temblor Ranges on the west, the Tehachapi Mountains and Mojave Desert on the south, and the Sierra Nevada Foothills and Mountains on the east.

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USGS1971

Base of fresh ground water approximately 3,000 micromhos, in the San Joaquin Valley, California

The southern eight-ninths of the San Joaquin Valley, about 10,000 square miles, is a broad structural trough bordered by the Sierra Nevada on the east and by the Coast Ranges on the west. In that area, fresh ground water is contained in principally unconsolidated continental deposits of Pliocene to Holocene age that extend to depths ranging from less than 100 to more than 3,500 feet. Because of widespread pumping of ground water, water levels have declined rapidly beneath extensive areas of the valley. Consequently, it becomes necessary to delineate the base of fresh water so that changes in thickness of the fresh-water zone can be monitored, and limiting depths of water wells can be determined. For the purpose of this study, a specific conductance of 3,000 micromhos per centimeter (about 2,000 milligrams per liter dissolved solids) was selected as a measure of the base of fresh groulid water. The base of fresh water was determined from data from electrical logs of wells, chemical analyses of ground water, and from numerous hydrologic and geologic reports. Because of the estimations of various factors used to interpret salinity from electrical logs, the base of fresh water as shown in this report must be considered to be only approximate. The base of fresh water is commonly in the continental deposits of Tertiary and Quaternary age, but in places along the eastern and western boundary of the valley it occurs in marine and continental sedimentary rocks of Tertiary age. In addition, it occurs locally in the igneous and metamorphic rocks of pre-Tertiary age of the Sierra Nevada. The configuration of the base of fresh water in places reflects underlying structure, but in other places, particularly along the eastern boundary of the valley, the base transgresses the structure. Furthermore, along and near the southwestern boundary of the valley, the base transgresses the major confining bed in the valley. Locally, the fresh-water body is overlain by water with a dissolved-solids` content that approaches and exceeds 2,000 milligrams per liter. And nearly everywhere in the valley, the fresh water is underlain by a basal, salinewater body of a sodium chloride type.

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USGS1971

Chemical quality of ground water in the Dos Palos-Kettleman City area, San Joaquin Valley, California

The Dos Palos-Kettleman City area of this report includes approximately 1,350 square miles on the central-western side of the San Joaquin Valley, California. Large-scale farming operations in the area have used ground water as the major source of irrigation water for nearly three quarters of a century. In 1968, completion of the San Luis Canal part of the California Aqueduct, made surface water available to farmers. In time the widespread use of this imported water may cause chemical-quality changes in the native ground water. To document conditions prior to any possible changes, 361 samples of ground water were taken before deliveries of surface water were begun. The data will serve as a base to which future investigations can be compared. To establish any trends, the results were compared to earlier chemical data for the area. The results indicated that only minor changes in chemical quality had occurred between 1951 and 1968. Water from an upper water-bearing zone is markedly different from water in a lower water-bearing zone. Water in the upper zone is of various chemical types, and the concentration of dissolved solids increases from east to west across the area. Water in the lower zone is a sodium sulfate type and is fairly consistent throughout the zone.

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USGS1971

Data for wells in the Modesto-Merced area, San Joaquin Valley, California

The Modesto-Merced area is in the northeastern part of the San Joaquin Valley. The area includes about 1,800 square miles that lie in the eastern portions of Merced and Stanislaus Counties. Specifically the boundaries are: North, the Stanislaus River; south, the Merced-Madera County line; east, the Merced-Mariposa and the Stanislaus-Tuolumne County lines; west, the San Joaquin River. Between September 1970 and May 1971, 859 wells were selectively canvassed in the area. The resulting data are on file in the U.S. Geological Survey office at 2800 Cottage Way, Sacramento, Calif. Selected well data are tabulated in table 1, and the location of these wells is shown on maps 1-65. Selected chemical analyses are shown in table 2. Table 3 is a listing of the well numbers of all wells canvassed in the area by the U.S. Geological Survey through April 1971.

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USGS1968

Geological literature on the San Joaquin Valley of California

The following list of references includes most of the geological literature on the San Joaquin Valley and vicinity in central California (see figure 1) published prior to January 1,1968. The San Joaquin Valley comprises all or parts of 11 counties -- Alameda, Calaveras, Contra Costa, Fresno, Kern, Kings, Madera, Merced, San Joaquin, Stanislaus, and Tulare (figure 2). As a matter of convenient geographical classification, the boundaries of the report area have been drawn along county lines, and to include San Benito and Santa Clara Counties on the west and Mariposa and Tuolumne Counties on the east. Therefore, this list of geological literature includes some publications on the Diablo and Temblor Ranges on the west, the Tehachapi Mountains and Mojave Desert on the south, and the Sierra Nevada Foothills and Mountains on the east.

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USGS1966

Ground water in the San Joaquin Valley, California

Ladies and gentlemen, it is a pleasure to be invited to attend this Irrigation Institute conference and to describe the Geological Survey's program of ground-water studies in the San Joaquin Valley. The U.S. Geological Survey has been making water-resources studies in cooperation with the State of California and other agencies in California for more than 70 years. Three of the earliest Geological Survey Water-Supply Papers--numbers 17, 18, and 19--published in 1898 and 1899, describe "Irrigation near Bakersfield," "Irrigation near Fresno," and "Irrigation near Merced." However, the first Survey report on ground-water occurrence in the San Joaquin Valley was "Ground Water in the San Joaquin Valley," by Mendenhall and others. The fieldwork was done from 1905 to 1910, and the report was published in 1916 as U.S. Geological Survey Water-Supply Paper 398. The current series of ground-water studies in the San Joaquin Valley was begun in 1952 as part of the California Department of Water Resources-U.S. Geological Survey cooperative water-resources program. The first report of this series is Geological Survey Water-Supply Paper 1469, "Ground-Water Conditions and Storage Capacity in the San Joaquin Valley." Other reports are Water-Supply Paper 1618, "Use of Ground-Water Reservoirs for Storage of Surface Water in the San Joaquin Valley;" Water-Supply Paper 1656, "Geology and Ground-Water Features of the Edison-Maricopa Area;" Water-Supply Paper 1360-G, "Ground- Water Conditions in the Mendota-Huron Area;" Water-Supply Paper 1457, "Ground-Water Conditions in the Avenal-McKittrick Area;" and an open-file report, "Geology, Hydrology, and Quality of Water in the Terra Bella-Lost Hills Area." In addition to the preceding published reports, ground-water studies currently are being made of the Kern Fan area, the Hanford- Visalia area, the Fresno area, the Merced area, and of the clays of Tulare Lake. Also, detailed studies of both shallow and deep subsidence in the southern part of the San Joaquin Valley are being made by the Subsidence Research Section at Sacramento, and research on permeability and specific yield in the San Joaquin Valley is being done by our hydrologic laboratory at Denver.

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USGS1962

Aquifer-test compilation for the San Joaquin Valley, California

This report is the first of a series the purpose of which is to make available in standard tabular form the results of aquifer tests that have been made by various private and public agencies in California. The scope of the compilation is to describe systematically, in a form agreed upon by the California Department of Water Resources and the Geological Survey, the (1) test location, (2) pumping data, (3) well data, and (4) summary of results. The results of these tests sometimes have been published but most frequently have been used only as a step in obtaining other information, consequently the results and even the location of aquifer tests have not been readily available. This report has been prepared by the Geological Survey under the immediate supervision of Fred Kunkel, district geologist for California, in cooperation with the California Department of Water Resources, and tabulates through October 1962 all tests analyzed by the Geological Survey for the San Joaquin Valley. The report is designed to be expanded when additional tests are analyzed or new tests are made.

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