Locks and dams

The United States Army Corps of Engineers (USACE) system is the most important component of the Ohio River Mainstem, because it is what shapes and forms the river itself. Beginning in 1824 the USACE was charged with the responsibility of making the Ohio River fit for navigation. It did so by building local and dams, the first in 1885 near Pittsburgh. In addition, it constructed levees and dams throughout the watershed to control the flow of water into the Ohio. As a result, the Ohio is no longer a free-flowing river. Instead, it is a series of 19 lakes whose elevation is constant.