The main drainages in southwestern Somerset county are the Casselman River and Laurel Hill Creek which flow into the Youghiogheny River along the southwest border. In the northwest, Stonycreek River, Shade Creek, and Quemahoning Creek (which flows into the Quemahoning Reservoir) are tributaries of the Conemaugh River. All these drainages are part of the Mississippi River Watershed. In the southeast, Wills Creek flows east into Bedford County and then into Maryland where it joins the Potomac River. Also, the headwaters of the Raystown Branch of the Juniata River are to the east of the town of Somerset. Both the Potomac and Juniata rivers are part of the Chesapeake Bay Watershed.