High Quality Content by WIKIPEDIA articles! Rainbow Springs, formerly known as Blue Spring, is a first-magnitude artesian spring formation in Marion County, Florida, USA, several miles north of the city of Dunnellon, Florida. Rainbow Springs is the focal point of Rainbow Springs State Park. The spring formation is the fourth-largest in Florida, and produces over 490 million gallons of water daily. Rainbow Springs forms the headwaters of the Rainbow River, which empties into the Withlacoochee River.