In the depression between Branstree and High Howes is a small tarn and the remains of a survey pillar. This unusual stone and concrete construction is cleft at the top to provide a sight line and was originally surrounded by a wooden frame, now decayed. This is one of four such pillars built during the construction of the Haweswater aqueduct. Below Branstree, Tarn Crag and Great Howe is the first section of the pipeline carrying water from the reservoir toward Manchester. The tunnel, some 1,300 ft below this point, required 250 tons of gelignite for blasting, and when constructed in the 1930s was the longest such pipeline in Britain. It emerges into Longsleddale below the southern end of Great Howe, where the spoil can still be seen.