Bulletin 1.pdf - California Department of Water Resources - State of ...

GROUND-WATER STORAGE CAPACITY OF THE
SACRAMENTO VALLEY, CALIFORNIA
By J. F. POLAND, G. H. DAVIS, F. H. OLMSTED and FRED KUNKEL
Purpose and scope of the investigation
In March, 1948, a cooperative agreement was made by the Geological
Survey, United States Department of the Interior, and the Division of
Water Resources, Department of Public Works, State of California,
providing for an investigation ofgeologic features of ground-water basins
in California.
At the request of the Division of Water Resources, the first activity
of the Geological Survey has been to make an estimate of the total groundwater
storage capacity of the near-surface water-bearing deposits in the
Sacramento VaHey. This valley has a surplus water supply-that is,
there is more surface and ground water jointly available than is now used
or than will be used in the valley in the future. The State desires to
know the order of magnitude of the ground-water storage volume to
assist in estimating the magnitude of the surplus.
The investigation summarized here relates to· total ground-water
storage capacity to a depth of 200 feet below the land surface. No attempt
has been made to estimate usable storage capacity 1 because such an
estimate would require detailed investigation of geologic and groundwater
conditions far beyond the scope of and funds available for the
present study. However, the work accomplished to date is a necessary
first step in an estimate of usable storage capacity. Accordingly, there
would be no duplication of effort if the more refined estimate of usable
storage capacity should be undertaken at a later date.
The area included in the estimate of storage capacity is shown on
Plate 1. It extends southward from Red Bluff beyond Sacramento, terminating
at the Cosumnes River on the southeast, apd at the northern edge
of the Sacramento-San Joaquin Delta on the south.
In addition to the estimate of underground storage capacity, the
full report now in preparation will include a section on geology, describing
the water-bearing deposits of the valley with respect to physical and
hydrologic character, thickness, distribution, and structural features.
The investigation is being made under the general direction of A. N.
Sayre, geologist in charge of the Ground Water Branch, and under the
immediate direction of J. F. Poland, District Geologist for California.
The field work and interpretation have been carried on almost wholly by
George H. Davis, Fred Kunkel, and Franklin H. Olmsted.
1 Usable storage capacity is that reservoir capacity that can be shown to be economically
capable of being dewatered during periods of deficient surface supply and
capable of being resaturated, either naturally or artificially, during periods of excess
surface supply. Obviously it must contain usable water, which may be defined as that
having a satisfactory quality for irrigation and occurring in sufflcient quantity in the
underground reservoir to be available without uneconomic-yield or drawdown.
( 621 )