--> ABSTRACT: Deep-Basin Groundwater Recharge in Southwest Indian Wells Valley, Kern County, CA, by James R. Ostdick; #91019 (1996)

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Deep-Basin Groundwater Recharge in Southwest Indian Wells Valley, Kern County, CA

James R. Ostdick

Hydrographs of monthly depth to water measurements in nested piezometers in southwest Indian Wells Valley indicate that the response to recharge in the deep wells is different than that of the shallow wells. The southwesternmost deep piezometer experienced the largest rise in water level after the spring snow melt and the largest overall rise after one year. The shallow wells do not show a similar increase. Given that heads vary with depth in the nested piezometers, this suggests the occurrence of multiple aquifers or strong vertical gradients.

Surface runoff from conventional mountain drainage areas does not appear to be the source of groundwater in the deep alluvial aquifers.

Geochemical analysis of water samples from eastern Sierra Nevada springs and streams and southwest Indian Wells Valley monitoring wells indicates the possibility of an extra-basinal source of recharge to the area's deep aquifer. Eleven stream samples with a mean total dissolved solids (TDS) concentration of 525 mg/L and a predominance of calcium bicarbonate and magnesium sulfate ions yielded mean stable isotope values of -11.8 ^pmil for {18}O and -91.0 ^pmil for deuterium. In contrast, groundwater samples from nine piezometers completed as deep as 2000 feet in the southwest valley showed a mean TDS of 251 mg/L, a sodium bicarbonate water type and mean stable isotope values of -13.3 ^pmil and -103.0 ^pmil. These data suggest that recharge may come from mountain sources with elevations igher than the local ephemeral stream drainages.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California