Tampa Bay is a large natural harbor and estuary connected to the Gulf of Mexico on the west central coast of Florida, comprising Hillsboro Bay, McKay Bay, Old Tampa Bay, Middle Tampa Bay, and Lower Tampa Bay. The surrounding area is home to about 4 million residents, making it a heavily used commercial and recreational waterway but putting much stress on the bay’s ecosystem, which once teemed with enough wildlife to easily support an extensive indigenous culture. Much greater care has been taken in recent decades to mitigate the effects of human habitation on Tampa Bay, and water quality has slowly improved over time.
The term “Tampa Bay” is sometimes used as shorthand to refer to all or parts of the Tampa Bay area, which comprises many towns and cities in several counties surrounding the large body of water. Local marketing and branding efforts (including several professional sports teams, tourist boards, and chambers of commerce) commonly use the moniker “Tampa Bay”, furthering the misconception that it is the name of a particular municipality when this is not the case.
Tampa Bay is Florida’s largest open-water estuary, extending over 400 square miles (1,000 km2) and forming coastlines of Hillsborough, Manatee and Pinellas counties. The freshwater sources of the bay are distributed among over a hundred small tributaries, rather than a single river. The Hillsborough River is the largest such freshwater source, with the Alafia, Manatee, and Little Manatee rivers the next largest sources. Because of these many flows into the bay, its large watershed covers portions of five Florida counties and approximately 2,200 square miles (5,700 km2). The bay bottom is silty and sandy, with an average water depth of only about 12 feet (3.7 m).
Tampa Bay’s shallow waters, sea grass beds, mud flats, and surrounding mangrove-dominated wetlands provide habitat for a wide variety wildlife. More than 200 species of fish are found in the waters of the bay, along with bottlenose dolphins and manatees, plus many types of marine invertebrates including oysters, scallops, clams, shrimp and crab. More than two dozen species of birds, including brown pelicans, several types of heron and egret, Roseate spoonbills, cormorants, and laughing gulls make their year-round home along its shores and small islands, with several other migratory species joining them in the winter. The cooler months are also when warm-water outfalls from power plants bordering the bay draw one out of every six West Indian manatees, an endangered species, to the area.
Tampa Bay has been designated an “Estuary of National Significance” by the United States Environmental Protection Agency. Two National Wildlife Refuges are located in Tampa Bay: Pinellas National Wildlife Refuge and the refuge on Egmont Key. Most of the islands (including several man-made islands built from dredge spoil) and sandbars are off-limits to the public, due to their fragile ecology and their use as nesting sites by many species of birds. The Tampa Bay Estuary Program keeps watch over the Bay’s health.[