Ground-water quality in the upper Santa Ana River basin, southern California

The principal ground-water quality problems in the Santa Ana River basin, as determined from two samplings (1968-69 and 1977-78), are high concentrations of dissolved solids in general and nitrate-nitrogen in particular. The distribution of dissolved solids exceeding 800 milligrams per liter was smaller in area in 1977-78 than in 1968-69. Distribution of nitrate-nitrogen exceeding 10 milligrams per liter was larger in area in 1977-78 than in 1968-69. Concentrations of dissolved solids and nitrate-nitrogen decreased with depth. The network of wells used in the 1977-78 sampling program provides only a general appraisal of overall quality for most of the upper Santa Ana River basin. It is not adequate for detailed appraisals of specific problem areas because it lacks sufficient areal coverage and construction information for the wells sampled. (Kosco-USGS)