The Orlando subdistrict area has the most varied surface-water and ground-water hydrology of any of the other subdistricts in Florida and features karst topography, wetlands, sand hills, sinkhole lakes, tidal streams, saltwater occurrence in coastal and inland ground waters and surface waters, 1st order magnitude springs, submarine springs, flowing wells, streams that terminate in sinkholes, recharge areas, and discharge areas. St.Johns River Water Managment District is our largest cooperator with South West Florida Water Management District, South Florida Water Management District, Reedy Creek Improvement District, Duval and Orange Counties, Lake County Water Authority, City of Orlando, and City of Cocoa being other substantial cooperators along with several other counties and municipalities.