Great-crested newts have helped prompt a £40,000 hike in cost for a project which aims to bring narrow boats back to a stretch of Cromford Canal.
The rare creature - one of only four amphibians protected in the UK - were found dotted along a 1.3 mile section of the canal from Cromford Wharf to Leawood Pumphouse which is being cleaned-up.
Their presence and the need to fell more trees than originally thought meant Derbyshire County Council have had to approve an extra £40,250 on top of the £300,000 they have already spent on the project.
The authority also approved £15,000 to replace a sluice gate at Cromford Mill which will help with water flow into Cromford Canal at a meeting on Tuesday, June 18.
Work to dredge the canal began in March.
Material such as decomposing plants and soil particles which get washed into the canal have been removed to make the water deeper, allowing a boat to use it for the first time since the 1980s.
The council owns the five miles of Cromford Canal, which is a designated Site of Special Scientific Interest, from Cromford Wharf to Ambergate. Parts of it also fall within the Derwent Valley Mills World Heritage Site.