Vandals have badly damaged a pond’s popular seating area.
Firefighters and police attended the blaze on Meadow Lane in Clayton-le-Woods.
Chorley Police said the fire to decking and seating areas was started deliberately between midnight and 12.20am on Thursday.
Michael Muncaster, chairman of Clayton-le-Woods Parish Council, said: “It’s actually something the parish council own, and was built by Environments for People
“We have numerous ponds in the parish and do a rolling programme of maintenance and updating.
“It’s only last year it was done and it’s cost a fortune.
“What we’ve done is ensure it is safe. I met with Bedrock Landscapes, who are one of our man contractors and they have made it safe.
“But we’re absolutely distraught about it.
“As a parish, it’s a lot of money.
“But it’s not just that, that particular pond is near an old folks’ home and we deliberately built it with a very slight wheelchair ramp so old folk could go down and feed the ducks.”
Mr Muncaster added that there had not been a vandal attack like it before there.
He said: “No, the only thing we’ve had before is the odd bit of graffiti and kids leaving empty beer bottles there.
“But certainly there’s been nothing to that extent.”
A Chorley Police spokesman said: “We are appealing for anybody who may have seen or heard anything suspicious or has any information regarding this incident to contact 101.”