Salt Balances in Ground Water

Continuing growth of population, industry, and agriculture in inland regions of Southern California has resulted in serious depreciation of ground-water gross mineral quality. An important factor is discharge to the ground of waste effluents containing the minerals in the original water supplies plus the increment resulting from conversion of water supplies to wastes. This problem has been intensified through importing supplemental water supply that has greater mineral content than the ground water. Agricultural use of water through evapo-transpiration is a second major factor that is also intensified through importation of waters of higher salinity. Regulatory interest has been initiated in California through the establishment of monitoring programs and exploratory controls. Factors influencing the salt balance of ground-water basins are evaluated, and presentations are made of available quantitative data together with examples of ground-water basin situations in which salt balance evaluations have been attempted. A comparison is made between the effects on increasing ground-water salinity of developing an area as an urban community, versus utilization of this same land for irrigated agriculture.