Sefton Central Labour MP Bill Esterson said he was deeply concerned by proposed changes to flood management brought about by funding cuts.
A 12-week consultation began this month after the Environment Agency put forward proposals to scale back or stop its rural land drainage in the area by 2015.
The plans have been announced after the Environment Agency saw its funding slashd by the Tory-Lib Dem government. They say the £3million a year it spends on flood risk management and land drainage in the Lower Alt and Crossens catchment is no longer sustainable.
The MP said the proposals were unbelievable and put the community in Sefton at risk.
Bill said: "I am extremely concerned by this report and its implications on residents in my constituency.
"The Environment Agency's strategic plan clearly states that the changes they are suggesting for the flood risk management of Sefton and West Lancashire are being brought about not as a means of improving the system, but because of funding cuts to the Environment Agency by the Tory-Lib Dem government.
"The changes will leave people's homes vulnerable to flooding and threaten farm land and crops.
"At a time when we know climate change is going to affect the risk of flooding, a fact identified in the report itself, we are seeing proposals here to scale back the pumping activity which is currently at the core of the flood defences in Sefton, particularly at the Lower Alt.
"This report also states that Sefton's agricultural land will be used as make shift flood plains. But Sefton boasts some of the best grade one agricultural land in the country. We should be using this land to grow our own food to become less dependent on foreign imports and reduce the rocketing price of food.
"The proposals being suggested by the Environment Agency also impact on Sefton's Core Strategy and the long-term future of the greenbelt which we in the Labour Party have been fighting to preserve from the Tory-Lib Dem government's relaxation of the planning laws in favour of developers building on previously protected countryside and greenspace areas.
"The impact of this report is huge and needs to be carefully considered. I will be contacting Defra and the Environment Agency personally to ask for clarification of some of the points in the report. And I am also urging wider public consultation of the document. I simply feel that not enough people are aware of the recommendations and the long term impact it will have on the communities within Sefton.
"Instead of just two drop-in sessions for the whole area affected, each and every community needs to have the chance to formally have its say on this report and I am calling on the Environment Agency itself to hold public meetings in Formby, Crosby, Maghull and Aintree, as well as in communities outside my constituency. It is vital people have a say in what is essentially a proposal which will radically alter Sefton in the years to come.
"My fear is that they will not be changes for the better and are being brought about because of ideological Conservative-Liberal Democrat cuts which are quite literally threatening people's homes right here in Sefton."