Quantifying and Prioritizing Opportunities for Canal Backfilling in Louisiana

Abstract

Canal backfilling-degrading and replacing the spoil adjacent to canals-has a wide range of potential benefits for the restoration of Louisiana coastal wetlands, but is not incorporated into current coastwide-scale restoration plans. This report seeks to characterize backfilling opportunities using GIS analysis of publicly available datasets to quantify and prioritize the area and distribution of spoil currently suitable for use as canal backfill. I used multiple filters to select backfillable spoil features based on the stability of the surrounding landscape, feature size, and proximity to Congressionally-authorized navigation channels or active oil and gas wells. Even this much-reduced extent of spoil indicated significant opportunities for backfilling distributed throughout the Louisiana coast. The Barataria, Mermentau, and Terrebonne hydrologic basins contained most of a total prioritized backfillable spoil area of approximately 10,775 hectares. The total is similar to the area of linear restoration projects included in Louisiana’s 2012 Comprehensive Master Plan for a Sustainable Coast. Coastwide canal backfilling could be accomplished for less than a third of the cost of those already-planned projects, and greater savings and performance could be achieved by combining backfilling with master plan projects whose footprints they intersect. Rough estimates of the value of wetlands that could be created through canal backfilling are $1.33 billion, or $0.14 billion per year. Estimates of the net present value of a crash program of coastwide backfilling ranged as high as $2.7 billion after 50 years.