Great Moss Swamp

The Great Moss Swamp (also known as the Loganburn Reservoir) is located in Otago, New Zealand, within the Maniototo region. It is near the Old Dunstan Road, a former gold mining route, approximately 85 kilometres northwest of Dunedin city centre. This area is classified as a regionally significant wetland.

Originally a swamp, the upper surface of the Rock and Pillar Range (the Rock and Pillars are a horst range, and thus have a very flat top) was transformed into a through the construction of a dam to store water for irrigation and hydroelectricity has turned the 'swamp' into a lake as part of the Maniototo Irrigation Scheme. The swamp is drained by the Logan Burn, which feeds into the Taieri River at Paerau. Despite the transformation, there are still significant areas of swampy wetland at the southwestern end of the lake.

The Loganburn Reservoir was completed in 1983, with a capacity of 85 million cubic meters of water. In 2014, the dam was raised by 80 cm, which included adding an 80 cm-high spillway and increasing the height of the coping wall along the top of the dam. This modification increased the storage by some 11.5 million cubic meters. The dam is located on the southern end of the Rock and Pillar Range, about 12 km south of Paerau, providing irrigation for 60 farmers and 9,300ha, and power generation when water is released for irrigation.