Geochemical and isotopic evidence for hydrologic processes at Owens Lake, California

Abstract

Dust mitigation at Owens Dry Lake requires an understanding of the hydrologic system because one proposed remedial strategy is flooding dust-producing areas with groundwater pumped from deep aquifers. This study uses geochemical evidence to define hydrologic processes. Solutes in shallow groundwater (< IO m) are controlled by evaporation, mineral dissolution, convective mixing, changes in salt morphology, diffusion, and partial lake desiccation. Deep groundwater in east and west portions of the basin is relatively old (>20.000 14 C yr) compared to groundwater recharged from the north (-7. 760 14C yr). Modern (< I 00 14 C yr) recharge discharges in margin springs. Groundwater from different depths mixes in a fault zone in the northeast portion of the lake bed. Geochemical evidence of downward groundwater flow contradicts current conditions of upward hydraulic gradients. Groundwater flow out of the basin required at least 12 m of surface water.