| Grassholme Reservoir | |
|---|---|
 Grassholme Reservoir seen from the Selset Reservoir outflow | |
  Grassholme Reservoir | |
| Location | England |
| Coordinates | 54°35′46″N 2°5′46″W / 54.59611°N 2.09611°W |
| Type | Reservoir |
| Primary inflows | River Lune |
| Primary outflows | River Lune |
| Managing agency | Northumbrian Water |
| Surface elevation | 310 m (1,020 ft) |
Grassholme Reservoir is a large reservoir in County Durham, England. It is situated in Lunedale, which is a side valley of the River Tees, about 2 miles (3.2 km) south of Middleton-in-Teesdale. It supplies water for Teesdale and Teesside and is owned by Northumbrian Water. Its main recreational use is as an angling centre.