Mid Colne Valley

Mid Colne Valley is a 132 hectare biological Site of Special Scientific Interest in Harefield in the London Borough of Hillingdon and Denham in South Buckinghamshire. Its main importance lies in its extensive diversity of birdlife in lakes in former gravel pits.

The site is divided into three areas. The great majority is in an area of four lakes bounded on the west by the River Colne and on the east by the Grand Union Canal. The river forms the boundary between Greater London to the east and Buckinghamshire to the west, and west of the river in Denham is a small area called Ranston Covert. The SSSI also includes a field called Coppermill Down east of the canal.

More information on the Wikipedia page.