WEST BAY BIRD ISLAND RESTORATION & ENHANCEMENT
West Galveston Bay, Texas

West Bay Bird Island is located in West Galveston Bay on the flood tidal shoal of San Luis Pass in Brazoria County east of Mud Island and north of Treasure Island. The island is a nesting habitat for a diverse population of colonial waterbirds, and has suffered severe long-term erosion. The scope of the project was to protect the island from further erosion and to restore the island’s marsh habitat. The project tasks included collection of historical geotechnical data, collection of bathymetric and topographic data, geomorphologic analysis, evaluation of causes of erosion, wave, tidal, and wind data analysis, numerical modeling of waves and tidal flow, and numerical evaluation of the proposed alternatives. As part of the engineering design, an alternatives analysis was performed to evaluate alternatives based on cost, performance, impact on the environment, and enhancement of the marsh habitat. The primary cause of erosion was identified as tidal channel migration. CHE developed an innovative solution to prevent and possibly reverse island erosion by implementing an underwater dike and a dredged relief channel to divert flow away from the island. This solution promotes natural accretion of the island. This phase of the project, Phase 1, was completed in May, 2003.

Phase 2 of the project included optimization of the selected alternative, permitting, final design, preparation of bid documents, and construction phase services. Construction involved dredging 66,700 cubic yards of sandy material from an approximate 1,500-foot linear diversion channel and utilizing this material to construct 4.9 acres of bird nesting habitat, 12.9 acres of marsh (10.8 acres of intertidal marsh and 2.1 acres of high marsh), and approximate 600-foot long protective bar. Construction began January 2007 and was completed in March 2007

CHE performed the following project tasks:

		Collected bathymetric and topographic data.
		Performed a geomorphologic analysis to determine the primary cause of erosion.
		Performed an alternatives analysis to determine the appropriate shore protection measure and marsh creation.
		Evaluated the alternatives for construction cost, maintenance cost, performance, natural resource impacts, and impacts on navigation.
		Performed numerical modeling of hydrodynamic effects of the proposed alternatives to determine the ability of the structure to perform as desired and to determine preliminary design criteria.
		Designed the preferred alternative consisting of marsh fill, vegetative planting, and dredging of a flow relief channel.
		Plans, specifications, and estimates were prepared, and bidding services as well as construction oversight services were provided.