National Geographic : 1970 Dec
"Clean enough to drink," says Frank Sebas tian of sparkling water that yesterday was sewage entering the pioneering treatment fa cility at South Lake Tahoe, California (below). His firm, Envirotech, of Palo Alto-one of the burgeoning companies devoted to pollution abatement-installed the chemical-reclama tion and sludge-burning systems for the plant. Voter's choice: As early as 1951, alarmed resi dents of the south side of Lake Tahoe deter mined to save its pristine waters. They ap proved plans and paid much of the $28,000,000 cost for a highly advanced sewage system. About 30 percent of the Nation's sewage plants utilize primary settling alone. An addi tional secondary stage, employed by another 60 percent, removes most pollutants and is the goal of federal water-quality standards for all cities by 1973. The Tahoe plant adds even more-sophisticated tertiary treatment. Cost for the entire operation averages less than three cents per day for each residence.