All that was wiki.........here again......is what someone else wrote...



This broad marshland of silt deposits along the river shore hampered access to the city’s waterfront, was a dumping ground for sewage and a breeding ground for malaria, and detracted from the capital city’s visual appeal. In 1882, Maj. Peter Hains of the U.S. Army Corps of Engineers submitted a plan that called for the dredging of the flats to create a large parkland with the reclaimed fill. A key feature of the plan was a tidal reservoir to serve both as a visual centerpiece and a means of flushing out the Washington Channel, a harbor separated from the river by the new fill lands. The reservoir would release 250 million gallons of water captured at high tide twice a day, flushing the channel free of sediments and impurities. The Reservoir and the Outlet Bridge, the structure that released the water to the channel, were completed in 1889; an Inlet Bridge to control the stored water was added in 1909.