| Flat Rock Reservoir | |
| Coords: | 44.1554°N -74.5515°W |
| Basin Countries: | United States |
| Area: | 194acres |
| Islands: | 1 |
| Cities: | Lower Oswegatchie |
| Pushpin Map: | New York#USA |
| Pushpin Label Position: | bottom |
| Pushpin Map Alt: | Location of Flat Rock Reservoir in New York, USA. |
Flat Rock Reservoir is located by Lower Oswegatchie, in St. Lawrence County, New York. Fish species present in the lake are largemouth bass, smallmouth bass, walleye, landlocked salmon, brown trout, white sucker, sunfish, rock bass, yellow perch, and black bullhead. There is a hard surface ramp launch access on county route 3.