SOMEWHERE ALONG THE ROAD FROM BROWNSVILLE to South Padre Island, at the southern tip of Texas’ Gulf Coast, things take a turn for the picturesque. Clues of the Port of Brownsville’s transportation industry—cranes, storage tanks, floodlights—vanish. To your left, the Bahia Grande, a 6,500-acre tidal basin, yawns into the distance. To your right, a swath of salt-tolerant black mangrove recedes toward the ship channel, sheltering nesting birds and filtering water. Tricolor squadrons of blue herons, great white egrets, and roseate spoonbills stalk their prey as enormous brown pelicans battle through heavy currents overhead. Somewhere, a rare ocelot lurks in a patch of thornscrub.
This is a land of exceptions. The Bahia Grande forms the heart of one of the largest wetland-restoration projects in U.S. history; just 15 years ago, the…