Winscar Reservoir is a upland reservoir located at Dunford Bridge in South Yorkshire, England, managed by Yorkshire Water. Built between 1972 and 1975, it was the last reservoir constructed along the River Don and the only one built under Yorkshire Water's tenure. The reservoir covers approximately 130 acres (51 ha) with a shoreline of around 3.1 miles (5 km). Its average depth is 58 feet (17.8 m), with a maximum depth of 137 feet (41.8 m), and it holds a water volume of over 323 million cubic feet. The reservoir sits within a catchment area of 2,040 acres (825 ha) and is surrounded by moorland, giving it the character of an upland lake.

Paddling access at Winscar Reservoir is strictly restricted. Yorkshire Water does not permit kayaking, canoeing, paddle boarding, or any other water sports unless the paddler is part of a club or organisation that has a formal agreement in place with Yorkshire Water. The Pennine Sailing Club does use the reservoir under such an arrangement and holds Royal Yachting Association status. Individual paddlers without such an affiliation are not permitted on the water. Swimming and wild swimming are also prohibited. Yorkshire Water cites several serious hazards specific to reservoirs: large underwater machinery operating continuously, strong currents, the risk of blue-green algae causing rashes and severe illness, and cold-water shock even during warm weather. The reservoir's considerable depth compounds these risks.

For those visiting the area for land-based activities, the dam head carries a road suitable for walking and forms part of National Cycle Route 68, with National Cycle Route 62 and the Trans Pennine Trail located just to the south. The dam head is also on the Yorkshire Water Way walking route. Parking is available at Broad Hill car park (40 spaces) and Windleden Lane car park (14 spaces), both of which fill quickly. The reservoir can be reached from Huddersfield by following the A616 south toward Holmfirth and then turning onto Dunford Road/A6024. A bus stop is available in Dunford Bridge and along Dunford Road.