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.
|Title||Suitability of irrigation water and changes in ground-water quality in the Lompoc subarea of the Santa Ynez River Basin, Santa Barbara County, California|
|Authors||R. E. Evenson|
|Publication Subtype||USGS Numbered Series|
|Series Title||Water Supply Paper|
|Record Source||USGS Publications Warehouse|