Lathkill

The River Lathkill is located in the Peak District National Park and is designated a SSSI. The site is part of a candidate SAC under the Habitats Directive. It is the only river in Britain which rises in, as well as flows through limestone for its entire length. The upper parts are a winterbourne, and in summer the stream issues from bubble springs lower down the valley. Downstream there are alternately moderately flowing gravelly sections and silted pools, some formed by natural tufa dams, others artificially. In the pools there are abundant submerged plants including species of Veronica, Ranunculus, Potamogeton and Callitriche, while faster sections are carpeted with bryophytes, some of which are nationally rare (eg. Cratoneuron commutatum).

There are no direct discharges to the river but the Knotlow cave system has recently been contaminated with sewage effluent and there is concern that this may eventually wash into the river. There are two licensed abstractions for fish rearing purposes and there are concerns over low flows which may affect water quality and the biota (the bottom 2km dried up completely in the summer of 1996). There was a suspected outbreak of crayfish plague in 1993 and crayfish have not been present in the invertebrate samples since that time.