| Cobb Reservoir | |
| Pushpin Map: | New Zealand South Island |
| Pushpin Map Alt: | Location of Cobb Reservoir |
| Location: | New Zealand |
| Coords: | -41.121°N 172.6578°W |
| Type: | reservoir |
| Inflow: | Cobb River |
| Outflow: | Cobb River |
| Date-Built: | 1949–1954 |
| Width: | 450m (1,480feet) |
| Volume: | 25600000m2 when full[1] |
| Elevation: | [2] |
The Cobb Reservoir is a hydro storage lake fed by the Cobb River in the Tasman District of the South Island of New Zealand. The reservoir feeds the Cobb Power Station and is above sea level but drops significantly with low rainfall.[3] Cobb Reservoir is the highest hydro storage lake in New Zealand, and is entirely surrounded by Kahurangi National Park.[4] The reservoir, dam, penstock and powerhouse are excluded from the national park.[5]
The dam that forms the reservoir was built from 1949 to 1954, replacing a smaller structure built about ten years earlier. It is an earth dam high by long. The geology of the area precluded the construction of a concrete dam.[6]
A narrow winding road leads over Cobb Ridge to Cobb Reservoir and along the lake's shore, providing access to tramping tracks in the area surrounding the valley. The road was built in the 1940s and remains unsealed from Cobb Power Station onwards.[1] The access road to the reservoir is the only road into the interior of Kahurangi National Park.[7]