Greenfield Valley is a river valley through Saddleworth Moor in England's Peak District National Park. Historically this area of the South Pennines was part of Yorkshire but since 1974 it has been within the eastern edge of the county of Greater Manchester. The valley's main stream Greenfield Brook is fed by Holme Clough and Birchen Clough. Greenfield Brook flows into Greenfield Reservoir and then on into Yeoman Hey Reservoir and Dovestone Reservoir. It then flows into Chew Brook which is a tributary of the River Tame, which feeds the River Mersey.