FM in Fort Pierce, which airs a classical music format. Metropolitan areas The Treasure Coast includes two metropolitan statistical areas designated by the Office of Management and Budget and used for statistical purposes by the Census Bureau and other agencies. These are: The Port St. Lucie, Florida Metropolitan Statistical Area, consisting of Martin and St. Lucie counties. Port St. Lucie is designated as the principal city. The two-county metropolitan statistical area was first defined in 1983 as the Fort Pierce Metropolitan Statistical Area. In 1993, the MSA was renamed the Fort Pierce-Port St. Lucie Metropolitan Statistical Area. In 2006, Fort Pierce was dropped as a principal city and the name was changed to its present form. The Sebastian – Vero Beach, Florida Metropolitan Statistical Area, which is coextensive with Indian River County. Sebastian and Vero Beach are designated as the principal cities. Geography All of the Treasure Coast is shielded from the Atlantic Ocean by narrow sandbars and barrier islands that protect the shallow lagoons, rivers, and bays. Immediately inland, pine and palmetto flatlands are abundant. Numerous lakes and rivers run through the Treasure Coast, notably the well known Indian River, a part of the Indian River Lagoon system. At certain seasons of the year, bridges may impede the red drift algae flow, causing a "rotten egg" hydrogen sulfide odor in the area. The Treasure Coast is also bordered by the Atlantic portion of the Intracoastal Waterway, a stretch of closed water from Brownsville, Texas, to Boston, Massachusetts. Communities A great amount of the Treasure Coast's population is made up of census-designated places (CDPs), with almost all of these in Martin County and Indian River County. Only one city on the Treasure Coast has a population of more than 100,000 inhabitants, which is Port St. Lucie in St. Lucie County. Here is the classification of the places of the Treasure Coast. C for city, T for town, and V for village. Place with more than 100,000 inhabitants Port St. Lucie (principal city) pop. 217,523 C Places with 10,000 to 50,000 inhabitants Fort Pierce pop. 43,601 C Sebastian pop. 23,344 C Stuart pop. 16,197 C Vero Beach pop. 16,017 C Places with 5,000 to 10,000 inhabitants Fellsmere pop. 5,439 C Indiantown pop. 6,083 V Places with 1,000 to 5,000 inhabitants Indian River Shores pop. 4,075 T Sewall's Point pop. 2,100 T Places with fewer than 1,000 inhabitants St. Lucie Village pop.