People needed for 'balsam bashing' along River Derwent
Volunteers are being invited to help halt the progress of Himalayan balsam, an invasive plant on the River Derwent.
The pink-flowered non-native species smothers riverside habitats, harms native plants and leaves banks bare and subject to erosion when it dies down.
It has to be pulled up before seed pods explode and spread along the river.
The Calver Weir Restoration Project and Peak District National Park rangers are holding a Himalayan balsam "bashing" day on Saturday.
Calver Weir environmental project manager Nick Quaife said a lot of children and teenagers had already taken part in the project over the past few weeks.
He said: "Large areas have now been cleared between Stoke Brook and Froggatt Old Bridge. We'd be very grateful if anyone else would like to come along on 7 August to help."
Himalayan balsam was introduced to the UK for ornamental gardens but spread into the wild.