More than two decades after the Clean Water Act was supposed to make America’s waters clean enough for swimming and fishing again, two iconic waterways — the great coastal estuaries of Puget Sound and the Chesapeake Bay — are in perilous condition. With polluted runoff still flowing in from industry, agriculture and massive suburban development, scientists fear contamination to the food chain and drinking water for millions of people. A growing list of endangered species is also threatened in both estuaries. As a new president, Congress and the states set new agendas and spending priorities, FRONTLINE correspondent Hedrick Smith examines the rising hazards to human health and the ecosystem, and why its so hard to keep our waters clean.