Rain and snowfall drains into three watersheds in Adams County.  A watershed is an area of land that drains into a lake or a river.  Watersheds can vary in size.  Some are just a few acres and others are millions of square miles.

Most of the land (approximately 73%) in Adams County drains into the St. Marys River Watershed.  The Saint Marys River Flows into Fort Wayne where it joins with the St. Joseph River to form the Maumee River.  The Maumee then flows directly to Lake Erie.

The Auglaize River Watershed drains approximately 5% of the land in Adams County.  This river is also a tributary of the Maumee River, joining in Ohio, and therefore ends its course in Lake Erie as well.

The third watershed in the county is the Upper Wabash River Watershed.  It drains the remaining 22% of the land in Adams County.  The Wabash River flows south to form the western edge of Indiana before exiting into the Ohio River.  The Ohio River flows to the Mississippi River, which ends its course in the Gulf of Mexico.