DEATHS of a number of fish at a reservoir have prompted an investigation.

An ecological survey will take place today to determine the extent of damage caused at Warnham Mill Pond Reservoir, Horsham, after a sluice gate was not closed and the pool emptied.

The Environment Agency was carrying out planned work to lower water levels, but there was a mechanical failure and the sluice gate could not close, a Horsham District Council statement has said.

As water drained, fish and silt were washed downstream into the Boldings Brook, a tributary of the River Arun.

An inspection of the river downstream revealed a number of fish died and there may have been other damage to the river bed.

Councillor Jonathan Chowen, cabinet member for arts, heritage and leisure, said: “The Mill Pond is an important and popular nature reserve and we are seriously concerned about the potential impact this incident has had on the ecology of the lake.

“It is too early to know the extent of the damage until the ecological assessment has been carried out. Once we have the results, we will be able to discuss appropriate remedies with the Environment Agency.

“In the meantime, I would like to thank our council officers who worked tirelessly to support the Environment Agency following the incident. The rescue operation that was mounted saved many fish that had got caught downstream. They did an excellent job in very difficult circumstances.”