Alder and Otter was founded in 1998 by Dr. Eleanor Harcourt, a freshwater ecologist who spent the previous two decades studying declining otter populations on the River Wye for the Nature Conservancy Council and its successors.

By the mid-1990s, otters were returning to stretches of the Wye that Dr. Harcourt had written off as lost. She became convinced that the recovery was not because of species-specific rescue programmes, but because of cumulative improvements to riverside habitat, water quality, and bank vegetation. “If you fix the river, the otter fixes itself,” she said in 1997, in what became the charity’s foundational argument.

She gathered a small founding board: two ecologists, a retired water engineer who had run pollution prosecutions for the National Rivers Authority, a farmer whose land bordered a Welsh tributary of the Wye, and a legal academic specialising in environmental law. With £12,000 of seed funding from a legacy, Alder and Otter was registered as a charity in September 1998.

The first restoration project was a 2 km riparian reinstatement on the Afon Cothi in Carmarthenshire. The charity now operates across thirty-seven catchments in England and Wales, with small satellite projects in southern Scotland. Dr. Harcourt stepped down as Chief Executive in 2019. She remains President and an active patron.