Environmental conditions of a backfilled pipeline canal four years after construction

Abstract

We studied the environmental conditions along 56 km of a backfilled pipeline canal four years after construction was completed. The canal traverses fresh, intermediate, brackish, and saline marshes in southeastern Louisiana. Over one-third of the sampling sections in the fresh intermediate marsh regained more than 60% vegetation cover; mean canal depth was 44 cm, and submerged aquatic vegetation (SAV) covered 59% of the bottom. The brackish marsh sections revegetated only where the canal passed through the mineral soils of the Bayou Lafourche natural levee; mean canal depth was 67 cm, and SAV covered 23% of the bottom. The salt marsh revegetated poorly; the area remained 80% open water, as it was before canal construction. Mean canal depth was 59 cm, and SAV covered 10% of the bottom. Backfilling did not return the marsh to its original condition, but the shallow ponds that formed along the canal resemble natural ponds in depth and vegetation.