The Dorlay () is a river that flows through the Loire department,

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. It is a tributary of the Gier, which in turn is a tributary of the

Rhône The Rhône ( , ; wae, Rotten ; frp, Rôno ; oc, Ròse ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and southeastern France before discharging into the Mediterranean Sea. At Ar ...

. The Gier valley was formerly heavily industrialized with coal and iron mines and factories.

Basin

The Dorlay rises in

Mont Pilat Mont Pilat or the Pilat massif is a mountainous area in the east of the Massif Central of France. Name The origin of the name "Pilat" is uncertain. The word may have a Latin origin (''Mons Pileatus''). Another legend says that the body of Pontiu ...

. It is long. Tributaries are the Artiole, Mornante and Sellon. The Mornante and Sellon are known for the presence of

white-clawed crayfish ''Austropotamobius pallipes'' is an endangered European freshwater crayfish, and the only crayfish native to the British Isles. Its common names include white-clawed crayfish and Atlantic stream crayfish. Distribution It is found from the easter ...

, a heritage species. The catchment area is about The source of the river is at an altitude of over , while the average elevation of the basin is The upper part of the basin is forested or pastureland.

Communities

A manuscript of 1200 gives the river the Latin name of Dorleum. In 1224 it is called Aqua de Dorllei. Subsequent mentions call it Rivus de Dorlay (1359), Dorleys (1527), Dourley (1718) and Dourlay (1789). It flows through the communes of

La Grand-Croix La Grand-Croix () is a commune and the seat of a canton in the Loire department in central France. It lies in the Gier valley. The commune was the main town of the former canton of La Grand-Croix, arrondissement of Saint-Étienne. It lies on ...

Saint-Paul-en-Jarez Saint-Paul-en-Jarez () is a commune in the Loire department in central France. Geography The Dorlay river, a tributary of the Gier that rises in the Pilat massif, flows through the commune. Population Twin towns Saint-Paul-en-Jarez is tw ...

, Lorette, La Terrasse-sur-Dorlay and

Doizieux Doizieux () is a commune in the Loire department in central France. Geography The village is situated southwest of Lyon. It is in the heart of the Parc naturel régional du Pilat. The Dorlay river, a tributary of the Gier that rises in Mont ...

. In the past, the river powered many weaving workshops in the valley.

Dam

Construction of a dam on the Dorlay by the town of Rive-de-Gier was discussed in 1884 but the project was abandoned due to cost. Today's ''Barrage du Dorlay'' is located at on the river between

and La Terrasse-sur-Dorlay. It was built between 1971 and 1973. The dam has a storage capacity of , with a catchment area of about . It is at an altitude of about . The dam supplies potable water to the municipalities of Lorette, Chateauneuf, Chagnon, Cellieu, St-Paul-en-Jarez, La Grand-Croix and part of Rive-de-Gier. In 2008 it supplied about of water to about 22,630 people. Since the dam is used for drinking water, swimming is not allowed - but some people swim anyway. Some local people use the dam for canoeing, but there are no rental boats.

Coal

In 1730 a large coal seam was found along the Dorlay. A number of mines were sunk to a depth of or more. These were worked for a short period, then abandoned due to lack of pumping equipment. Mining resumed in 1776 with pumps operating, but was abandoned in 1792 due to the volume of water entering the mines from the Dorlay. The river's path marks a geological fault in the Loire coal basin. In 1838 the Saint-Philippe mines were sunk on the right bank of the Dorlay to a depth of , but did not find any significant coal deposits.

References

Citations Sources * * * * * * {{DEFAULTSORT:Dorlay Rivers of France Rivers of Auvergne-Rhône-Alpes Rivers of Loire (department)