Dredging is the underwater excavation of sediment that builds on the bottom of a river. As the Army Corps of Engineers began to change the river, new sandbars formed where they didn’t want them, so they began frequent dredging to keep the channel clear for boats.In 1831 Captain Henry Shreve thought it was a good idea to shorten the Mississippi River portage route by 15 miles so he dredged a loop in the river to make a more direct connection the the Atchafalaya river, but he didn’t realize he was changing the shape of the entire delta, so the Corps had to step in. The river started changing course to the Atchafalaya because of its lower elevation, the the Corps created the Old River Control Structure in 1963 to regulate how much water flows into the Atchafalaya, which is now 30% of the water. This is one of many structures made to help keep the Mississippi in its place.

A spillway is a row of doors in a levee that open to let the floodwaters out. They protect levees from overtopping by diverting floodwater away from the main river. The Corps built three spillways, and we often drive over one on our way to the kayak tour. The Bonnet Carre spillway is the most used and has been opened 10 times since 1937, diverting up to 250,000 cfs into Lake Pontchartrain. It was opened in 2008 and this year.

All of the ways we have altered the river has changed the ecosystem of the Mississippi River floodplain by preventing seasonal floods that supplied freshwater and nutrients to more than 90% of the floodplain. This denies species from access to millions of acres of foraging, spawning, and nursery habitat. This critical habitat has been reduced from 24 million acres to less than 4.4 million acres, and crop farms have taken over half of the original floodplain.