Lake Tahoe, astride the California-Nevada stateline in the Sierra Nevada Mountains, is one of the clearest, deepest freshwater lakes in the world. As the growth of resident and tourist populations alike increases at an accelerated rate, the problems associated with sewage and other waste disposal are magnified and the clarity and beauty of Lake Tahoe waters are threatened by algal nuisances that may arise from the nitrogen and phosphorus contained in these wastes. Likewise, silt from land clearing practices and real estate development is an increasing problem. The report discusses the nutrient and silt problems, the present status of sewage treatment and disposal, the water quality characteristics of lake waters, and the pollution abatement proposals designed to protect and preserve the quality and beauty of the interstate waters of Lake Tahoe. (Author Modified Abstract)