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R. E. Evenson

Publications and source records attributed to R. E. Evenson.

10 recordsLinked to original sources
USGS1966

Hydrologic inventory of the Lompoc subarea, Santa Ynez River basin, Santa Barbara County, California, 1957-62

Hydrologic data collected during the climatically near-average 6-year period of inventory 1957-62 provide the basis for making estimates of supply to and demand from the Lompoc subarea of the Santa Ynez River basin and changes in the quantity of water stored in the deposits of the basin. The hydrologic inventory presents gains or accretions to the water supply, as inflow, equated with loss by water demands, as outflow. The difference is the ground-water storage change. Items of inflow include precipitation, surface and subsurface inflow, irrigation return, and sewage effluent. Items of outflow include surface and subsurface outflow, evapotranspiration, and water pumped for irrigation and other uses. Ground-water storage changes occurred as depletions of the shallow water body beneath the eastern and central parts of the Lompoc plain and beneath the upland part of the Lompoc subarea to the north and east. The estimated annual depletion of storage averaged 3,000 acre-feet. A near balance between inflow and outflow is indicated by a calculated difference of 5,000 acre-feet of accretion and an observed depletion of ground water in storage of about 3,000 acre-feet. The difference of 8,000 acre-feet between the two values, considering the magnitude of total inflow and outflow--110,000 and 105,000 acre-feet, is not significant. For the period of inventory, more water was discharged from the basin by flow in the Santa Ynez River than by pumping from wells. The near balance between inflow and outflow for a period of near-average climatic conditions, in general, substantiates a previous estimate that perennial pumpage is as much as about 20,000 acre-feet. However, water in storage will be depleted if the progressive change in the ratio of irrigation pumpage to other pumpage continues. Even though the hydrologic balance is maintained, changes in chemical quality of the ground water, due to recycling of irrigation water and inflow of poor-quality connate water from the consolidated rocks, indicate that chemical equilibrium has not been reached. Perennial supply under the 1957-62 conditions of inventory is estimated to be between 24,000 and 26,000 acre-feet.

California↗
USGS1966

Utilization of ground water in the Santa Maria Valley area, California

Overdraft in the Santa Maria Valley ground-water basin since about 1946 has resulted in a significant decline in water levels throughout the basin as ground water has been removed from storage. In 1959 approximately 2,200,000 acre-feet of ground water was in storage above sea level in the ground-water reservoir. Estimates of storage depletion are not consistent with estimates of groundwater recharge and discharge. The natural perennial yield of the basin probably is about 50.000 acre-feet, on the basis of estimated recharge and natural discharge. The augmented perennial yield probably is about 70,000 acre-feet and includes 21,200 acre-feet of water per year released at Twitchell Dam. Storage depletion, not estimated in the seaward ends of the aquifers, will result as the fresh watersea water interface moves landward in response to the continuing decrease in hydraulic gradient in the aquifer system. Evidence of sea-water intrusion into the basin has not been observed, but limited sea-water encroachment may have occurred at the offshore ends of the aquifers. Additional observation wells will be necessary to provide supplemental data to insure that hydraulic heads and gradients in the deeper aquifers are properly monitored.

Water Supply Paper↗
USGS1965

Suitability of irrigation water and changes in ground-water quality in the Lompoc subarea of the Santa Ynez River Basin, Santa Barbara County, California

Analyses of water samples collected since 1934 from some of the irrigation wells in the Lompoc subarea of the Santa Ynes River valley have shown a gradual deterioration in the chemical quality of the water. Most of the ground water pumped in the subarea has a dissolved-solids contents ranging from about 700 to about 2,000 parts per million, of which sulfate and chloride are the predominant constituents. Suitability of the water for irrigation is variable and is dependent principally on "potential salinity" of the water, soil permeability, and type of crop. Changes in water quality are not consistent throughout the subarea. No doubt the chloride concentration increases as a result of both the recycling irrigation water and inflow of high-chloride low-sulfate connate water from the consolidated Tertiary rocks. The influence of recycled irrigation water is indicated by increase concentrations of chloride and sulfate in a ratio of 1:2. Inflow of high-chloride low-sulfate connate water is indicated by increased chloride concentration correlated with little or no change in sulfate concentration. Peak chloride concentrations in three local areas are probably the result of the inflow of connate water. Furthermore, ground-water gradients in each of the local areas are favorable for inflow from the consolidated rocks.

Water Supply Paper↗
USGS1962

Ground-Water Reconnaissance at Pinnacles National Monument, California

Ground-water supplies at Pinnacles National Monument have been obtained from springs that occur in fractures and along bedding planes of volcanic flows and deposits, and from springs discharged from perched water in a sedimentary fanglomerate formation. The spring-water yield is barely adequate to supply existing camp facilities, and therefore a supplemental water supply is necessary before existing campgrounds can be expanded. This supplemental water can be supplied by good-quality ground water obtained from shallow wells drilled in the alluvium of Chalone Creek. The yield of properly constructed wells in this area should exceed 10 gallons per minute.

Water Supply Paper↗