As we have continued our tour of the Mermentau Watershed, there are common themes which have arisen. The communities of Lake Arthur and Grand Chenier, LA are perhaps the most vulnerable in the lower watershed region, as their geographic locations place them directly in, or hydraulically connected to, the lower Mermentau Basin (which includes White Lake and Grand Lake). There is a belief, right or wrong, that the US Army Corps of Engineer’s operation of the Gulf Intercoastal Waterway (GIWW) has raised the flood threat to the Lower Mermentau Basin, and Lake Arthur in particular. Upstream stakeholders in places such as Acadia & Evangeline Parish, and specifically Church Point have voiced support of providing relief in the Lower Mermentau, as they understand that once downstream relief is provided, those improvements can continue upstream. Everyone we have visited with agrees that relief must start downstream. While adding upsatream capacity must also be part of any flood relief solution, In this update we will briefly discuss history of the lower Basin and potential improvements.
Lower Basin Historic Hydrology
As the locals there know, and others such as myself have come to learn, the current infrastructure surrounding the Lower Mermentau Basin have cutoff the natural flood outfall through the coastal marshes south of Lake Arthur.