There are a number of tarns on Potter Fell, of which Gurnal Dubs and Potter Tarn are the most significant. Potter Tarn is located at the bottom of the ascent to the unnamed summit (395 m). The tarn supplies water to Croppers Paper Mill in Burneside and its flow is moderated by a concrete dam. The present water level is around half of its 1990 level, when the dam was lowered. The outflow from Potter Tarn issues into Ghyll Pool before the stream descends towards the paper mill. Gurnal Dubs is a popular place for recreational fishing and the licences are managed by the Kent Angling Association. It is located to the west of Ulgraves and south of the unnamed summit (395 m). The tarn is home to a boathouse that was renovated in 1985.