The western flank is named Willie Wife Moor for reasons lost to antiquity. It is bounded by Birkside Gill to the north and Raise Beck to the south, Reggle Knott being the only area of rough ground. At the base of the slope Raise Beck flows north to Thirlmere, having been diverted as a part of the 1884 reservoir project. It previously turned south down the other side of Dunmail Raise pass to feed Grasmere. Before this diversion, Dollywaggon Pike was distinctive in that its drainage reached the sea at more widely spread points than any other Lakeland Fell, with Raise Beck going through Grasmere and Windermere to reach Morecambe Bay, Birkside Gill going through Thirlmere and Derwent Water to reach the Irish Sea at Workington and Grisedale Beck draining into Ullswater and then to the sea at the Solway Firth. This is still the case today when there is enough water in Raise Beck for it to flow both north and south, but normally Seat Sandal now has this distinction.