River Etherow

River Etherow
River
The Etherow (left), joined by the Black Cloughs from Bleaklow.
Country	England
Source
- location	Featherbed Moss, South Yorkshire
- elevation	500 m (1,640 ft)
Mouth
- location	River Goyt
- elevation	80 m (262 ft)
Length	30 km (19 mi)
Basin	77.7 km2 (30 sq mi)
The River Etherow is highlighted in red (click to enlarge) Coordinates: 53°27′54″N 1°58′51″W / 53.464956°N 1.980954°W / 53.464956; -1.980954

The River Etherow is a river in northern England, and a tributary of the River Goyt. Although now passing through South Yorkshire, Derbyshire and Greater Manchester, it historically formed the ancient county boundary between Cheshire and Derbyshire. The upper valley is known as Longdendale. The river has a watershed of approximately 30 square miles (78 km²), and the area an annual rainfall of 52.5 inches (1,330 mm).

Rising in the Redhole Spring and Wike Head area of Pikenaze Moor in Derbyshire, the river broadens into the Longdendale Chain of reservoirs in the Peak District National Park. It emerges again in Tintwistle, Derbyshire, at the foot of Bottoms Reservoir dam and passes Melandra Castle in Gamesley, where it is joined by Glossop Brook. The Etherow enters the borough of Tameside at Hollingworth in Greater Manchester, passing into Stockport where it passes through Etherow Country Park. It flows into the River Goyt at Brabyns Park near Marple.

The modern accepted start of the River Mersey is at the confluence of the Tame and Goyt, in central , 4 miles (6 km) downstream. However, older definitions, and many older maps, place its start at the confluence of the Etherow and Goyt; for example the 1911 Encyclopædia Britannica states "It is formed by the junction of the Goyt and the Etherow a short distance below Marple in Cheshire on the first-named stream." John Stockdale's map published on 12 April 1794 shows the Mersey River extending to at least Mottram, and forming the boundary between Cheshire and Derbyshire.