A plan to build a stretch of road between Nenagh and Thurles in Co Tipperary could endanger one of Lough Derg's main trout-spawning rivers.
Councillors in North Tipperary have passed a plan to widen and realign the Nenagh to Thurles road at Latteragh by diverting the Nenagh river.
The decision could see the destruction of a main salmon- spawning and nursery channel and the eventual reduction of trout stocks in the Nenagh river - a traditional wild brown trout habitat and a principle spawning ground on the east side of Lough Derg.
The decision to build the road has been made despite warnings by the Shannon Regional Fisheries Board that the road realignment would destroy one of the last remaining "untouched" sections of the Nenagh river.
In a letter to the council the fisheries board warned the proposal would "completely remove a meandering channel of river, which contains pockets of spawning gravel for trout".
"Spawning habitat will be lost and nursery area for trout will be lost," the board added in the letter. Anglers are deeply concerned about the effect the re-channelling of the river will have on trout stocks.
Mr Joe O'Donoghue, secretary of the Ormond Anglers' Association, said: "This area cannot be rehabilitated because you simply can't recreate what nature has put in place over the years."
Acting Director of Services for Transport and Emergency Services with North Tipperary County Council, Mr Marcus O'Connor, said the existing road at Latteragh was very busy, has poor alignment and is extremely hazardous.
"The situation represents a significant hazard to road-users and will continue to deteriorate unless works are undertaken," said Mr O'Connor.
He said the selected road alignment option, involving the diversion of the river, was the council's preferred choice because other routes would involve the excavation of rock.