Cherry blossoms..............and tidal basins..........

How Does The Tidal Basin Work?

The Cherry Blossom trees, Jefferson Memorial, FDR Memorial, and MLK Memorial all border the Tidal Basin. Ever wonder what it does and how it works?

The concept for the Tidal Basin originated in the planning for the reclamation of the Potomac flats in the 1880s. 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.

Rising Tide: The inlet gates open to allow water from the Potomac River to enter the Tidal Basin during the rising tide, while the outlet gates close to store incoming water in the basin and block the flow of water and silt up the Washington Channel into the basin. The automatic inlet gates remain open while the water level in the river rises to high tide. The force of water rising into the channel pushes the outlet gates closed.

Falling Tide: As the tide begins to ebb, the general outflow of water from the basin forces the inlet gates to close. The same force is applied to the outlet gates which open outward into the channel. Silt buildup is swept away by the extra force of water running through the Washington Channel from the Tidal Basin. The inlet gates will remain in the closed position as long as the water level in the basin is higher than or equal to the level of the river upstream of the inlet gates. As a new tidal cycle begins, the water level of the river rises while the water level in the basin remains constant and the gate movement is repeated.

See the Tidal Basin and the memorials lining it, as well as the famous Cherry Blossom trees, on our Tidal Basin & Cherry Blossom Tour.