Morganza Spillway emergency use to divert additional water from the Mississippi River into the Morganza floodway, which merges downstream with the Atchafalaya floodway before entering the Gulf. Diversion of water from the Mississippi's main channel has the effect of lowering water level in the Mississippi downstream of the spillway, helping to relieve stress on levees and other flood control structures both upstream and down. Besides controlling flooding in a given event, the system is also designed to prevent the Mississippi River from permanently altering course down the Atchafalaya River, bypassing Baton Rouge and New Orleans. Water that passes the Morganza Spillway first
Pequannoc Spillway site in poor repair. Like its sister structure the Pompton Dam, the Pequannoc Spillway was originally made entirely of timber. Constructed in the early 19th century the Pequannoc Spillway aided in navigation upriver along the Morris Canal during its almost 100 years of use. The structure was also part of a system to maintain water levels along portions of the Pompton River and Ramapo River which were at the time of their construction a part of the Morris Canal. The removal of the spillway was advocated against in the 1920s by C.C. Vermeule, Decommissioning Engineer for the Morris Canal and