In the beginning, the problem was very clear-- water pollution was visible to everyone in the nation. In 1969 we saw the Cuyahoga River in Ohio burst into flames. Historic Boston Harbor was a cesspool, and so was the Potomac River in Washington, D.C. Lake Erie was declared dead and the 1969 oil spill off scene in Santa Barbara, California, contributed to the public outrage and the call for immediate reforms. Water pollution is the introduction into fresh or ocean waters of chemical, physical, or biological material that degrades the quality of the water and affects the organisms living in it. Water provides for use in homes and industries, for irrigation, for extinguishing fires, for street cleaning, for carrying wastes to treatment facilities, and for many other purposes. The three most important factors in any water supply are its quality, the quantities available, and the location of the water supply relative to the points of use. Each type of water use has its own prerequisites. Food processing plants, for example, need large volumes and high water quality; waste conveyance systems require only volume. When the Clean Water Act first became a law in 1972, it focused on the most visible an repugnant water pollution sources - sewage outfalls, industrial waste discharges, and other "point sources," so named because the pollution that comes from them can be traced to one place and then easily controlled. But the drafters of the original Clean Water Act largely overlooked non-point sources of water pollution. Major sources of non-point pollution include runoff from streets and lawns, erosion from disturbed hillsides, and use of agricultural pesticides, fertilizers, and manure. Because of their scattered sources, these types of pollution can be difficult to control, but their effects can be seen in bodies of water across the continent. The risks and hazards of pollution have become very clear across the nation as the problem has progressed.