Lough Scur

Lough Scur (Irish: Loch an Scoir, meaning 'the lake of the horses, pasturage, troop') is a freshwater lake in south County Leitrim, northwest Ireland. It is part of the Shannon–Erne Waterway. There have been human settlements here since the New Stone Age. Modern features include quays and moorings. Protected features are Castle John, three Crannogs, and the causeway into Rusheen Island, though "Jail Island" is not protected. The ecology of Lough Scur, and indeed all county Leitrim lakes, is threatened by pollution and invasive species such as curly waterweed, zebra mussel, and freshwater clam.

Fanciful folklore of the 19th century claimed Lough Scur was named from Oscar son of Oisín, and his grave lay at Aghascur, "the field of the Scur". However, it is pointed out the word "Scur" (Irish: Scor, genitive scuir) has various meanings, and probably translates to "lake of the horse-stud". O'Donovan suggests Scuir means 'lake of the camp', and the placenames database of Ireland suggests Lough Scuir means 'lake of the horses, pasturage, troop'.

Lough Scur is about 1 kilometre (0.6 mi) northwest of Keshcarrigan. It covers an area of 1.14 square kilometres (0.4 sq mi). Lough Scur is deep with generally a soft mud or compact peat bottom, the shallowest portion is the northern reach, between Driny and Drumcong, probably due to the large quantity of detritus carried into it by a mountain stream at Kiltubrid townland. Beyond the roscarbon shoal there is an isolated rock almost level with the summer water surface, nearly circular, measuring c. 10 – c. 15ft across. Lough Marrave might be considered a continuation of Lough Scur, as they share the same level and connected by a half-mile channel. Keshcarrigan lough is connected to Lough scur by a small stream about 250 metres (820.2 ft) in length. Carrickaport Lough drains into Lough Scur by a 450 metres (1,476.4 ft) stream running through Drumcong townland. Drumaleague Lough, lying 1 kilometre (0.6 mi) to the south west, is connected via the Shannon–Erne Waterway. Sub-glacial Rogen moraine landforms are evident in the valley between Slieve Anierin and Lough Scur, caused by ice age glaciers moving northeast to southwest over millions of years, the Morainic drift heaping up thousands of drumlins in the surrounding lowlands.

Fish present in Lough Scur include "roach-bream hybrids" (54%), Roach (22%), Perch (9%), Bream (9%, including. Skimmers), Pike (6%), nine-spine stickleback, and Eel. The large proportion of hybrids results from the Pike here preferring Roach (86%), Stickleback (9%), and Perch (4%) in their overall diet. The pike population is the "native Irish strain" (Irish: liús meaning 'Irish Pike') not the other European Pike strain (Irish: gailliasc meaning 'strange or foreign fish'). Large pike have been caught here weighing 10 kg (22 lb) or more. When surveyed in 2002, no zebra mussels were reported at the highest water level, and in 2005 the water quality was rated as mesotrophic.

Lough Scur forms part of the Shannon–Erne Waterway, lying at the summit of the canal connecting Lough Scur to the River Shannon, just south of Leitrim village. The original canal was constructed in the 1840s, fell into decline as the rail network prospered, but was reopened in 1994 to develop the region's tourism industry. The levels of Lough Scur are controlled by Waterways Ireland via two Spillways. The recording of large numbers of ancient dug-out canoes from county Leitrim remind us that waterways have always been a key means of transport in Ireland.

The primary human settlements at Lough Scur are the villages of Keshcarrigan and Drumcong.

Mesolithic hunter-gatherers may have frequented Lough Scur sometime c. 8,000 – c. 4000BC. Archaeological finds from Lough Scur include five Lithic flakes, a polished shale axe, a dolerite axe roughout, and a piece of leather under a dugout canoe. The leather and canoe are not dated, but the flakes are probably Mesolithic.

Raftery (1957) claimed small Stone Age crannogs were observed at Lough Scur. The pre-Bronze Age material were described as flat, circular sites of stones, 6-10m in diameter and 400 cm above the lake mud. The interiors often consisted of brushwood, irregularly sized stones and sometimes horizontal timbers, some charred. Charred animal bones were found on the surface, indicating swine (wild boar, domestic pig) and oxen were part of the diet.