The following is a brief, and very basic description of the surface water, and ground water resources found in Hillsborough County.

Hillsborough County is in a sense fortunate because in general, there is an abundant amount of water, both surface water, and ground water, found within the county boundaries. With regard to surface water, there are three major river systems, the Hillsborough, the Alafia, and the Little Manatee, which pass through the county on their way to Tampa Bay. And in addition to these major rivers, there are numerous smaller streams which sometimes feed water to the rivers, and at other times simply flow on their own across smaller drainage basins. There are also hundreds of lakes of different sizes scattered across the county, with a particularly high proportion of these located in the eastern, and northwestern parts of the county. These river systems, streams, lakes, and of course their associated wetlands, are important features of Hillsborough County, and as such are valuable to different people, for different reasons. Some folks enjoy the fishing, and recreational benefits of these surface water features. Others appreciate the aesthetic beauty of our surface water bodies, and for that reason choose to make their homes near them.

With regard to ground water in Hillsborough County, there are essentially three ground water bodies, or aquifer systems which are found beneath the land surface; the Surficial Aquifer, the Intermediate Aquifer, and the Floridan Aquifer. Of these, the Surficial Aquifer typically begins within a few feet of land surface, and as such is the ground water body that has the greatest amount of connection with lakes, and other wetland features. In fact, for the most part in Hillsborough County, lakes are surface expressions, or "out croppings" of ground water from the Surficial Aquifer System. Directly beneath the surficial aquifer, and depending on where you are in the county, there are the two deeper aquifers known as the Intermediate Aquifer, and the Floridan Aquifer. In terms of area, the Intermediate Aquifer generally extends from its northern limit which is at about State Road 60, southward well beyond the county line. 

The Floridan Aquifer extends beneath the entire land area of the county, and in the portion of the county south of State Road 60, the Floridan Aquifer is found at greater depths and is beneath the Intermediate Aquifer. North of State Road 60 where the Intermediate Aquifer is generally absent, you basically have two aquifer layers underground, the Surficial Aquifer which begins at or near land surface, and the Floridan Aquifer which lies underneath the Surficial Aquifer. South of State Road 60, there are three aquifer layers underground, because not only do you have the Surficial Aquifer on top, and the Floridan Aquifer at greater depths beneath it, but there is also the Intermediate Aquifer between the two. The three aquifer systems in Hillsborough County, which are essentially reservoirs of water found underground in a "layer cake" type arrangement, can and often do exchange water between themselves. When this happens, it is said that the aquifers are "leaky."