Clio Logo
Entries on This Tour

This Tour is a Virtual Museum or Site Tour.

Our Coast

Created by Kate Tannian on May 22nd 2020, 7:54:47 pm.

Get a QR Code for this tour


By the 1700’s the Mississippi River had shifted paths back and forth several times - spreading sediment and creating land at the end of an ever-changing delta. The Pontchartrain Basin stretches out into the Gulf of Mexico as a 10,000 square mile watershed from the Mississippi River to the Pearl River and includes 16 Louisiana Parishes and 4 Mississippi Counties. The construction of levees along the Mississippi River prior to the 1927 flood prevented communities from being flooded but also cut off the nutrients, freshwater and sediment that nourished our wetlands. During the 1927 flood, it became clear that the levees alone were not enough to protect communities and outlets were needed along the river relieve flood waters. During the flood, the levees were breached at Caernarvon and flood waters lowered near New Orleans. The realization that relief outlets were need prompted the construction of the Bonnet Carré Spillway in the 1930's. In the 1930’s logging of cypress trees in the coastal swamps for their valuable wood resulted in saltwater intrusion from the logging canals (and later the oil and gas canals) which prevented new cypress from growing. This and the introduction of the invasive nutria (Myocastor coypus), which feed on young cypress, prevented natural swamp regeneration. Ultimately the loss of the cypress destroyed the buffer against storms that the coastal swamps provided the urban areas. In the 1940’s nutria, an invasive species of rodent brought in from South America, added to the coastal woes. A voracious eater of wetland vegetation roots, the nutria has annihilated miles of protective marshland. As the century continued, oil and gas became prominent economic drivers and critical resources for our nation. Access to these was provided by navigation canals and pipelines which crisscrossed South Louisiana marshes. Unfortunately, in the process, the coastal marshes were lost when spoil banks were left randomly throughout the area, disastrously altering the natural hydrology of the region. The canals caused saltwater intrusion and more land was lost. Looking back through the 20th Century, to a large degree, the reduced coastal hurricane protection for South Louisiana was the result of poor decisions made in the 1900’s.