The cost of the January floods to Cumbria could top £250m, insurers say.
The floods saw boats used by rescue workers in Carlisle
The Association of British Insurers (ABI) says work to repair damage to affected communities in the county could take months to complete.
It says the total cost of winter storms to the entire north of England and southern Scotland could be £500m.
The government is likely to foot a large part of the bill, with seven local authorities in the county so far making official requests for help.
An ABI spokesman said: "We are looking at between £200m and £250m for the damage in Carlisle and Cumbria.
"If that were to include the rest of the north of England and southern Scotland, we are talking about £500m."
Parts of Carlisle are still uninhabitable, with many homeowners and businesses still awaiting insurance settlements.
Cumbria request for state help
Cumbria County Council
Carlisle City Council
Eden District Council
South Lakeland Council
Allerdale Borough Council
Copeland Borough Council
Cumbria Police Authority
Carlisle City Council chief executive Maggie Mooney said: "We are working with the insurance companies and with our insurers and with the government as well."
She said an application had been made for government help under a scheme to help local authorities in emergency situations.
A spokeswoman for the Office of the Deputy Prime Minister (ODPM), said it was considering what help could be given to stricken areas under the so-called Bellwin Scheme, which was set up in 1983.
So far the scheme has helped with the costs of the 1987 hurricane, which swept parts of the UK.
It was also used to help alleviate hardship during the foot-and-mouth outbreak in 2001.
She said: "The help we can give is limited to uninsurable costs, which require immediate work, such as the removal of rubbish and trees and repairs to paths and pavements.
"Before we can allocate any money the local authority concerned must have committed 0.2% of its annual revenue to the problem and must make a claim within two months of the emergency.
"Up to 85% of costs above that may be met with cash from government."
Mrs Mooney said the overall cost to the city council was so far about £8m, of which £1m had already been earmarked from reserves.