The purpose of the wastewater management plan is to provide adequate treatment and disposal for sewage from a present day population of 90,000 persons in Contra Costa County. The locality studied includes extensive residential, agricultural, industrial and recreational areas bounded on the north by the Sacramento and the San Joaquin Rivers. The River system is subject to important beneficial uses including fish and wildlife habitat, recreation and freshwater withdrawal for irrigation, domestic supply and industrial use. The proposed project provides for conveyance of sewage located to the east of Pittsburg; Local secondary treatment and land disposal and discharge to the surface waters of the Sacramento Bay and estuary.