| Lough Alewnaghta | |
| Pushpin Map: | Island of Ireland |
| Pushpin Map Alt: | Lough Alewnaghta location in Ireland |
| Pushpin Label Position: | none |
| Pushpin Map Caption: | Location in Ireland |
| Location: | County Clare, County Galway |
| Inflow: | Derrainy River |
| Outflow: | Lough Derg |
| Catchment: | 26.25km2 |
| Basin Countries: | Ireland |
| Length: | 1.3km (00.8miles) |
| Width: | 0.5km (00.3miles) |
| Area: | 0.55km2 |
| Depth: | 4m (13feet) |
| Max-Depth: | 4.5m (14.8feet) |
| Elevation: | 31m (102feet) |
Lough Alewnaghta is a freshwater lake in the Mid-West Region of Ireland. It is located in Counties Clare and Galway.
Lough Alewnaghta measures about 1.5km (00.9miles) long and 0.5km (00.3miles) wide. It is about 23km (14miles) south of Portumna near the western shore of Lough Derg. The lake lies largely in County Clare with a smaller portion in County Galway.
Fish species in Lough Alewnaghta include perch, roach, bream, pike and the critically endangered European eel.