A biogeographic study of submerged aquatic vegetation (SAV) in the Pontchartrain Basin of southeastern Louisiana was conducted. These plants provide numerous essential ecosystem services. Eighteen species occurred in different salinity zones ranging from freshwater to the saline waters of the Gulf of Mexico. Lake Pontchartrain SAV coverage was reduced by 70 percent from 1953 to 1990 due to increased turbidity from urbanization and shell dredging. A La Nina drought (1998-2001) increased SAV to 80 percent of the 1953 coverage, but declines occurred after the drought and there was extensive damage from Katrina and other hurricanes between 2005 and 2012.