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In this July 29, 2011, an aerial view of the Kennedy Center for the Performing Arts, center back,  Key Bridge, center, and Memorial Bridge, foreground, and the Potomac River in Washington.  Water quality in the Potomac was already bad and has grown worse in the past five years, as the river responsible for much of the District of Columbia's drinking water faces upstream pressures from forest loss and farming and downstream stress from growing development, the Potomac Conservancy said Thursday, Nov. 10, 2011.   (AP Photo/Cliff Owen) Cliff Owen / AP Photo