The Saline River watershed is located in southern Illinois and flows in an easterly direction encompassing over . The watershed covers land within Hamilton, White, Franklin, Williamson, Gallatin, Johnson, Pope, Hardin, and Saline Counties. The mainly agricultural landscape has many small streams, creeks, and man-made lakes that flow into the Saline River which eventually enters the Ohio River where it is wide. The Lake of Egypt, an impoundment on the upper end of the South Fork Saline River, is the largest lake in the watershed, and covers .