Grand Tower Island lies on the left bank of the Mississippi River in a remote area between
St. Louis,
Missouri and
Cairo,
Illinois. It shares its name with the adjacent small city of
Grand Tower, Illinois, as well as with the landmark
Tower Rock island on the Missouri side of the river. Despite its location on the eastern side of the river and its road connections to Illinois, the island is part of
Brazeau Township, Perry County, Missouri, in a situation analogous to the right-bank river village of
Kaskaskia, Illinois. A towhead (a narrow island much longer than its width) approximately long lies in the river between Grand Tower Island and the Missouri mainland. Some parts of the lake are susceptible to disappearing via
evaporation, although the lake occasionally reconnects with the river for short periods of time; its water normally trickles into the nearby
Big Muddy River, which
flows into the Mississippi nearby. Measuring approximately east-west and north-south, Grand Tower Island is traversed by a single north-south road, Island Road, that travels south from Grand Tower, crosses the island, turns sharply eastward to run along the narrow strip of land between the lake and the lowest section of the Big Muddy River, and then proceeds southeastward to connect with
Illinois Route 3. Road access to the rest of Perry County requires a one-way trip of more than via the
Chester Bridge at
Chester. ==Lake and fishing==