Charlotte Harbor, in southwest Florida, is a semi-enclosed body of water open to the Gulf of Mexico through several tidal inlets. The harbor is America's 17th largest estuary and Florida's 2nd largest open-water estuary, with an open-water surface area of about 270 square miles and an average depth of seven feet. The harbor and its adjacent estuaries make up one of the most pristine and productive coastal ecosystems in the state of Florida. The harbor, which comprises Lemon Bay, Charlotte Harbor Proper, and Pine Island Sound, receives fresh water from three major rivers (Peace, Myakka, and Caloosahatchee) and several smaller streams that mix with the marine waters of the Gulf. Depending on the season, location, and depth in the harbor, salinity can range from zero to full-strength seawater.
The region is home to five national wildlife refuges, five state aquatic preserves, and one state buffer preserve. It supports a great diversity of semitropical plant and animal life. In 1995, Charlotte Harbor was recognized as an estuary of national significance and was accepted into the National Estuary Program. A remarkable feature of the region is that nearly all the wetlands surrounding the harbor are designated as state buffer preserves and are publicly owned.
Excerpted from website of the Florida Department of Environmental Protection: