Lake Pepin is a naturally occurring lake, and the widest naturally occurring part of the Mississippi River, located approximately 60 miles downstream from Saint Paul, Minnesota. It is a widening of the river on the border between Minnesota and Wisconsin. The formation of the lake was caused by the backup of water behind the sedimentary deposits of the Chippewa River's delta. It has a surface area of about 40 square miles (100 km2) and an average depth of 18 feet (5.5 m), which makes it the largest Lake on the entire Mississippi River.
Then the rain came.