Three Sisters Springs is a complex of three spring areas, with vents, and sand boils that help feed Kings Bay, the headwaters of the Crystal River.

In 1893, Florida passed its first law designed to protect the manatee. In 1907 the law was revised to add a $500 and/or six months of jail penalty for molesting or killing a manatee. In 1966, Congress enacted the Endangered Species Preservation Act, the manatee was one of the first species to be added to this act. On March 11, 1967 the United States Fish and Wildlife Service classified the manatee as endangered and in threat of extinction.

In 1972, the Florida manatee received the federal designation as a marine mammal which offered it further protection under the Federal Marine Mammal Protection Act. This act made it illegal to remove any marine mammal, and imposed a fine of up to $2000 and/or one year in jail for doing so. In 1973, The Endangered Species Act of 1966 was revised to increase the federal protection of manatees. This revision made it a violation to harass, harm, hunt, wound, pursue, shoot, capture, kill, or collect an endangered species, and also authorized cooperative agreements between the federal government and states with funding management, research, and law enforcement.

The Sirenia Project was established in 1974 in Gainesville, Florida. This project was established to provide documentation and rescue programs for the manatee. In 1976, Sea World in Orlando opened a Manatee Rescue and Rehabilitation Program which continues today. The Florida Manatee Sanctuary Act was passed in 1978 and Florida became an official refuge and sanctuary for the manatee. The Florida Manatee Sanctuary Act allowed for the regulation of boat speeds in areas where manatees inhabited. In that same year, the U. S. Fish and Wildlife Service, along with the Florida Audubon Society and Sea World, sponsored the “West Indian Manatee Workshop”. The workshop proposed regulations to control boaters and divers, pursue land acquisition for refuges, study the potential of artificial refuges, and to explore technological control mechanisms to protect manatees, along with ways to increase public education.

In 1988 the U.S. Fish and Wildlife Service received funding to purchase a site on Kings Bay to headquarter the Crystal River National Wildlife refuge offices and visitor center. At this time the Florida State Land Acquisition Selection Committee purchased the Homosassa Springs project through its Conservation and recreation Lands Program.

Manatee Protection Zone Beginning in 1991, the USFWS has conducted annual aerial surveys of the manatee population in the state of Florida. Due to uncontrollable factors such as water clarity, weather conditions, and areas of limited water surface visibility, these numbers are simply a minimum count and are not considered to be accurate. The 1991 survey count revealed 1,267 manatees statewide. In 2001 the population survey counted 3,300 manatees and in 2011, the survey showed 4,834 manatees in Florida state waters. Again, these numbers are minimum figures and don’t take into account the manatees that were not visible by aircraft during the survey.