The Aquifer Resource Index (ARI) was created by the Southwest Florida Water Management District (SWFWMD) to provide information to the media, residents, local governments and other interested parties about current groundwater conditions and how they are compared to historical records. The underlying purpose of this index is to provide the public with a gauge of groundwater levels in their area, so they can develop an understanding of the severity and cycles of drought and recovery. In order to do this, the groundwater information presented in the monthly document "Hydrologic Conditions" was restructured into a regional context that would be recognizable to the general public. The three regions used in this index are defined by county boundaries.
To read detailed monthly reports, visit SWFWMD’s website: https://www.swfwmd.state.fl.us/resources/weather-hydrology/hydrologic-conditions-reports. In the northern region (Citrus, Hernando, Lake, Marion and Sumter counties) the Floridan Aquifer is at or near land surface, allowing rainfall to easily recharge (replenish) the aquifer system. In the central region, (Hillsborough, Pasco, Pinellas and Polk counties), the Floridan can be unconfined or confined (overlain by clay soils). Where the Floridan is confined, recharge by rainfall is low. In the southern region (Charlotte, DeSoto, Hardee, Highlands, Manatee and Sarasota counties) the Floridan is confined.