More than 1,000 employees at the Environment Agency have applied for voluntary redundancy, although compulsory job cuts could still be made, according to sources.
Unions fear up to 1,700 jobs are set to be axed at the agency despite the flooding crisis which has gripped parts of the UK this year.
The agency asked for staff to express an interest in taking voluntary redundancy and it is now believed that around 1,200 workers have applied.
Sources told the Press Association that not all those who have applied will be allowed to leave because of the nature of the work they are involved in.
That leaves open the possibility of several hundred compulsory redundancies at the agency.
Prime Minister David Cameron was questioned about job losses earlier this month at the height of the flooding but said nothing would happen while the crisis was being tackled.
Unions have suspected that the agency will re-start negotiations over redundancies once the flooding eases.
Some officials have reported that morale among EA staff is low because of criticism of the way the agency has handled the floods.
Some staff were withdrawn from the Thames Valley for a while earlier this month because of abuse from local residents.
Unison general secretary Dave Prentis said: "It is time for the Government to withdraw the threat of compulsory redundancies at the Environment Agency. The continuing uncertainty around job losses and the stress of an ever-increasing workload is already driving some staff to jump before they are pushed.
"Workers from all sections of the agency have been out on the front line protecting communities and proving their worth through the whole floods crisis. It is an insult that up to 1,000 staff are still at risk of redundancy."
Justin Bowden, national officer of the GMB union, said, "Money may be no object according to the Prime Minister but apparently common-sense is. The storm damage and flooding events of the last three months show beyond all reasonable doubt that the jobs at the Environment Agency are a vital public service which, if they are lost, will have an irreversible cost for individuals and the public purse.
"Everyone can see that to cut jobs at the Environment Agency is penny wise and pound foolish in the extreme. There is no social, moral or financial case that can be made to cut EA jobs and leave the country more vulnerable to floods and drought than recent events have already shown it to be.
"MPs of all parties must maintain the pressure on the Prime Minister to reverse the planned 1,700 job cuts and 10% cut to the agency's budget because, as things stand, his claim that 'money is no object' rings hollow."