The valley carries Borrow Beck for 11 kilometers , from Borrowdale Hole, through Borrowdale Moss to End of Borrowdale, crossing the A6 road at High Borrow Bridge and reaching the River Lune at Low Borrow Bridge, site of a Roman fort, and where the original bridge has been supplemented by a new bridge for the A685 road, twin viaducts for the M6 motorway, and the West Coast Main Line railway.