The major aquifers in the study area (Blount, Cherokee, DeKalb, Etowah, Jackson, and Marshall Counties in northern Alabama) are the Knox-Shady, Tuscumbia-Fort Payne, and Pottsville aquifers. These aquifers are sources of public water supply and are recharged in each of the six counties. Major aquifers are susceptible to contamination from the surface throughout their recharge areas. In addition, water in these aquifers is highly susceptible to contamination in general topographic settings such as poorly drained areas and in areas where specific features such as sinkholes occur. (USGS)