Terrebonne Parish Wide Forced Drainage System Supplemental Information Report PDF Download

The forced drainage plan consists of 26 proposed and 5 unauthorized projects. The latter projects were begun about the time that Federal wetland permitting procedures were being initiated. All projects were designed to provide controlled drainage for existing and future development along natural levees (the high ground) in the parish. The projects were not designed to protect against major floods but will provide protection against minor floods. Alternative levee alignments that were considered included: 1) entirely within nonwetland areas; 2) along wetland/nonwetland interfaces; 3) entirely within wetlands; and 4) 'no action'. Implementation of the 'no action' alternative would further stress the existing inadequate drainage facilities. Implementation of the wetland/nonwetland alternative would result in improved drainage facilities and would provide protection from minor tidal and back water flooding of enclosed areas. Other anticipated impacts that would expected to occur would include: 1) unavoidable and permanent losses of wetland and nonwetland areas and associated functions; 2) isolation of wetland areas; and 3) modifications of turbidity, suspended particulates, sedimentation and other physical and chemical regimes and ecosystem attributes. Additionally, the potential for the release of toxic materials, including heavy metals, also exists.