The company has cut a swathe through scrubland in preparation for replacing an old water main in the valley.
The Men of the Trees say 40-year-old willows have been felled and wildlife habitats destroyed.
St Peter Deputy Collin Egré has accused Jersey Water of ‘wanton vandalism’ and Environment president Senator Philip Ozouf is calling for work to cease so that countryside officers can carry out an investigation before the project reaches proposed Sites of Special Interest higher up the valley.
Both Members said they would be speaking to Jersey Water’s managing director Howard Snowden.
