Kingsmill Reservoir is located on the Sutton In Ashfield and Mansfield border in Nottinghamshire. Once a mediaeval mill pond it was expanded in the late 1830s. Created for a head of water to power a dozen mills along the River Maun, along with the water meadows several miles away. It is now a wildfowl sanctuary with a 1.5 mile walk around the perimeter.

In 1837 the 4th Duke of Portland was requested by his tenants and other water powered mill owners on the River Maun in Mansfield, that a large regulated head of water was needed to ensure continuity of a water supply all year round, as to avoid disruption to the businesses. To create this reservoir the Duke had to flood 72 acres of his farmland. The 72 acre site was cleared of topsoil using man power, carts and horses. The deep clay deposits around the area provided the essential material to make water tight seal. The dam was constructed using thousands of tons of limestone and clay in a cut and fill operation at Kingsmill. The reservoir took about two years to complete. The water was regulated by the control sluices situated on top of the dam. These are hidden in the undergrowth today.

At the northern end of the reservoir is England’s oldest railway viaduct, built in 1817. Known as the Portland Bridge, it was built from locally extracted limestone. It was built 20 years before the dam was constructed and the River Maun flowed through the centre arch. The bridge carried the Mansfield and Pinxton Railway over the River Maun. The track had a sharp bend at Kingsmill which was not suitable for the later steam powered trains, the bridge became redundant in 1871 after the bend was smoothed out by the building of a new bridge further down river.

Although large, the reservoir is quite shallow, in places around six foot deep. It contains some very large Carp, fish to 30lb have been reported but are elusive. Roach, Bream and Hybrids are also present, the pegs at the dam end where the depth is around 6ft giving the best chance of success. Night fishing is not allowed and there is a Closed season from the 15th March to the 31st April Inclusive.

Kingsmill is the start of the Timberland Trail and overlaps on the Maun Valley Trail, both of which present walkers with idyllic settings, including several heritage ponds along the river. The reservoir provides a good habitat for a wide range of wildlife, and is good for walks, fishing, nature study and sailing.