The Great Lakes watershed (HUC-2 region 04) drains the Great Lakes basin, one of the largest freshwater systems on Earth, ultimately flowing to the St. Lawrence River. Covering 325,302 sq mi across 12 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Great Lakes…

The Ohio watershed (HUC-2 region 05) drains the Ohio River and its tributaries across the central Appalachian and Midwest regions into the Mississippi. Covering 162,922 sq mi across 11 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Ohio watershed map below to explore…

The Upper Colorado watershed (HUC-2 region 14) drains the headwaters of the Colorado River from the Rocky Mountains through Utah and Arizona. Covering 113,348 sq mi across 5 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Upper Colorado watershed map below to explore…

The Rio Grande watershed (HUC-2 region 13) encompasses the Rio Grande basin from Colorado south through New Mexico and along the US-Mexico border to the Gulf. Covering 230,844 sq mi across 4 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Rio Grande watershed…

The Missouri watershed (HUC-2 region 10) drains the Missouri River basin, the longest river in North America, from Montana east to its confluence with the Mississippi. Covering 521,013 sq mi across 12 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Missouri watershed map…

The Texas-Gulf watershed (HUC-2 region 12) drains the rivers of coastal Texas and Louisiana directly into the Gulf of Mexico. Covering 183,222 sq mi across 3 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Texas-Gulf watershed map below to explore all 11 HUC-4…

The South Atlantic-Gulf watershed (HUC-2 region 03) stretches from Virginia to Florida and west to Louisiana, draining into the Atlantic Ocean and Gulf of Mexico. Covering 285,695 sq mi across 9 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive South Atlantic-Gulf watershed map…

The Mid Atlantic watershed (HUC-2 region 02) encompasses the Mid-Atlantic states, including the Chesapeake Bay and Delaware Bay drainage systems. Covering 106,751 sq mi across 12 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Mid Atlantic watershed map below to explore all 7…

The Arkansas-White-Red watershed (HUC-2 region 11) drains the Arkansas, White, and Red Rivers across the southern Great Plains and Ozark Plateau. Covering 247,960 sq mi across 8 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive Arkansas-White-Red watershed map below to explore all 14…

The New England watershed (HUC-2 region 01) drains the rivers and streams of New England, flowing primarily into the Atlantic Ocean and the Gulf of Maine. Covering 76,768 sq mi across 8 states and provinces, it is one of the 18 major drainage regions of the contiguous United States. Use the interactive New England watershed…