Water-quality investigation, Salinas River, California

Concentrations of dissolved solids in the Salinas River are variable and range from 164 to 494 milligrams per liter near Bradley and from 170 to 1,090 milligrams per liter near Spreckels. Higher concentrations near Spreckels are caused mainly by sewage inflow about 150 feet (50 meters) upstream. Concentrations of nitrogen, phosphorus, total organic carbon, selected trace elements, and pesticides also generally increase downstream from Pozo to Spreckels and are related to sewage effluent; however, high concentrations occur elsewhere in the river.

Specific conductance and water discharge regression results indicate that relations were all significant at the 1-percent probability level at Paso Robles, Bradley, and Spreckels, with the explained variance ranging from 66 to 74 percent. Concentrations of nitrogen, phosphorus, total organic carbon, and trace elements are only infrequently related to water discharge.