The elusive mammal saw numbers tumble in the face of toxic pesticides which damaged their health and reduced their food supplies of fish, to the point they had almost disappeared from England by the 1970s.
But a ban on the chemical pesticides and improvements in water quality in rivers across England has led to a turnaround in their fortunes, the latest survey by the Environment Agency showed.
The fifth otter survey of England, which examined 3,327 river sites across the country between July 2009 and March 2010, showed the number of places with evidence of otter life had increased tenfold in 30 years.
Evidence of otters was found at 58.8 per cent of sites in 2009-2010, up from just 5.8 per cent in 1977-1979 and an increase from 36 per cent in the last survey in 2002.
But the boom has not been uniform, with East Anglia and the River Thames showing the biggest rise since the 2002 study.
Rivers in the South West and the River Wye catchment are now thought to be supporting the maximum number of otters possible, with waterways in areas such as Northumbria, Cumbria and the upper Severn close to capacity.
Recovery has been slowest in the South East, with Kent the only county in England not to have seen otters return, the survey found.
But the Environment Agency predicts they will spread into Kent within the next 10 years, and the species will fully recover across England in less than two decades.
Paul Raven, head of conservation and ecology at the Environment Agency, said: "The otter is at the top of the food chain and, as such, is an important indicator of the health of English rivers."