Shopkeepers and residents are urged to be prepared in case of extreme flooding.
Andrew Coen from the Environment Agency said that if extreme flooding was to hit Brighouse then the town centre, Armytage Road Industrial Estate, and Brookfoot would all be under water.
This will only happen once every 100,000 years but when that day will be nobody knows.
But if the worst was to happen Mr Coen said there was no reason why the town couldn’t be back on its feet providing a plan was put in place which can be activated when the balloon goes up.
The map was revealed at one of Calderdale Council’s flood drop in sessions held at Brighouse Civic Hall.
The sessions were held immediately after the floods in July and August last year in Hebden Bridge, Todmorden and Mytholmroyd. But due to the amount of people wanting to know what future plans were being put in place to prevent flooding throughout Calderdale, the meetings were extended to the borough.
The meetings were run by Calderdale Council, the Environment Agency, Yorkshire Water, the Canal and River Trust, National Flood Forum and Community Foundation for Calderdale.
John O’Grady from the council’s flood team said there were only a few areas of Brighouse affected by the flooding last year including Brookfoot, Briggate and down River Street. “We have been sharing information and helping people to help themselves be more flood responsive,” he said.
“In the Upper Calder Valley, £3 million has been invested by the council to repair things damaged by the floods.
“But any work we do in the Upper Valley will not transfer the problem to the Lower Valley. We have a multi agency approach, all working together in harmony to decide where the most important investments are required.”
A detailed report should be published later this year into some of the investigations being carried out by the agencies into the plans for the future.
They are using the hydraulic model of the River Calder which should be able to explain why areas like River Street flooded last year.
They will look at the opportunities to improve wash land to take water out of the river at peak times using the model.
There are 6,500 premises on the at risk list held by the Environment Agency although Brighouse isn’t classed as a high priority because flooding is not as severe as in other areas.
However the agencies would like to form a flood action group in the Lower Valley run by local people for local people.
The town centre last flooded in 1946.