Potential Effects of Increased Ground-Water Pumpage on Barka Slough, San Antionio Creek Valley, Santa Barbara County, California.
GEOLOGICAL SURVEY MENLO PARK CALIF WATER RESOURCES DIV
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Ground-water use in San Antonia Creek valley, California, is expected to increase significantly as a result of a planned extensive agricultural development in the basin. This additional pumpage may cause significant stress on the ground-water system, particularly on the environmentally sensitive Barka Slough. Expectations of the developer are that about 6,640 acre-feet per year of consumptive ground-water use will be required to irrigate 2,500 acres of vineyards and 1,200 acres of truck-farmed vegetables. This represents an increase in net basin pumpage of about 60 percent. The developer plans to obtain this water from 12 large-diameter irrigation wells in the Harris Canyon area. Analysis of the potential drawdowns in the vicinity of Barka Slough, by using the Theis nonequilibrium formula, indicates that drawdowns would average 6 feet after 10 years of pumping and would eventually exceed 10 feet. Because the artesian head in the aquifer that supplies the slough is generally less than 3 feet above land surface, these declines would probably mean that the wetlands of Barka Slough would disappear. The effects of this particular agricultural development would be in addition to any decline caused by other increases in pumpage in the basin. Author
- Hydrology, Limnology and Potamology