The organisation that helped save England's otters has launched an appeal for funds.
There are 12 pairs of breeding otters at the Trust
The Otter Trust at Earsham on the Norfolk border with Suffolk faces a big bill for a flood prevention scheme at its own headquarters.
It needs £40,000 to ensure its future and is only just recovering after visitor numbers fell during the foot-and-mouth crisis.
Philip Wayre founded the Trust in 1971 with his wife Jeanne.
He said: "There would be no otters virtually in the whole of England now had it not been for the Trust's re-introduction programme.
"That's the single most important thing we've ever done."
By 1999, the Trust had bred and released 120 otters into the country's rivers.
There are 12 pairs of breeding otters at the centre, which attracts 20,000 visitors a year.