A watershed is an area of land that water drains across on its way to a common body of water.
Watersheds are delineated by USGS using a nationwide system based on surface hydrologic features. The United States is divided and sub-divided into successively smaller hydrologic units which are classified into four levels: regions, sub-regions, accounting units, and cataloging units (the smallest). Each hydrologic unit is identified by a unique hydrologic unit code (HUC). The cataloging unit level of classification is assigned an 8-digit HUC. The 8-digit HUCs for the United State’s portion of the Lake Erie Watershed are shown on the map.
Ohio’s portion of the Lake Erie Watershed
Ohio’s portion of the Lake Erie Watershed covers 11,649 square miles, drains portions of 35 counties with a population of 4.65 million people. Of that land, 73% is agricultural or open space, 20% is wooded, 4% is urban, 2% remains wetland and 1% is inland lakes and rivers.