National
| Auchengaich Reservoir | |
| Pushpin Map: | Scotland |
| Location: | Glen Fruin, Scotland |
| Coords: | 56.086°N -4.7705°W |
| Type: | Reservoir |
| Outflow: | Auchengaich Burn |
| Basin Countries: | Scotland, United Kingdom |
| Area: | 34000m2 |
| Elevation: | 244m (801feet) |
Auchengaich Reservoir was created in 1942 through the construction of an earthfill dam built by the military to supply water to Helensburgh and the Gareloch during World War II.[1]