| Keystone Lake | |
| Location: | Armstrong County, Pennsylvania, U.S. state |
| Coordinates: | 40.7506°N -79.2859°W |
| Type: | reservoir |
| Pushpin Map: | Pennsylvania#USA |
| Pushpin Map Alt: | Location of Keystone Lake in Pennsylvania, USA. |
Keystone Lake (also known as Keystone Reservoir and Plum Creek Reservoir) is a reservoir in Armstrong County in the U.S. state of Pennsylvania. The elevation of Keystone Lake is above sea level.