At Sacramento, a system for collection of combined wastewater flows was developed in the late 1800s. In 1946, the City of Sacramento (City) abandoned the practice of combining stormwater and sanitary waste collection in new system construction. Beginning in the 1950’s, the City undertook a modernization program of reconstruction to separate combined sewers where feasible. Under this program, storm flows have been isolated from large areas of the collection system. Even so, 6,800 acres of the city continues to be served by combined sewers. Sanitary flow from an additional 2, 800 acres of separated sewer area is tributary to the combined sewer system.