The London Borough of Waltham Forest is a London borough in East London and forms part of Outer London. It is a mix of built-up residential development and a fifth of the borough is made up of forestland, reservoirs, open space, parks and playing fields. It is located between part of Epping Forest in the east and the River Lee in the west which form two green corridors, passing into London from the surrounding countryside. It is sometimes confused with the adjoining Epping Forest district, which is not in Greater London.