Northern Ireland faces the biggest public sector cuts in a generation, Finance Minister Sammy Wilson has warned.
He used a keynote speech to send the message to ministerial colleagues that they face tough decisions on how to manage the Assembly's finances.
And the minister told the Institute of Revenues, Rating and Valuation at Belfast City Hall that the Stormont administration must decide how much longer it can delay water charges.
The new Conservative-Liberal Democrat coalition Government recently imposed cuts of £128 million on the Northern Ireland administration, but more drastic reductions in public spending are expected. Mr Wilson said: "These are challenging times and over the next few years we will see massive reductions in public expenditure, not seen since the 1970s.
"While not of our making, we must rise to this challenge so that key frontline public services can be delivered in the best way. It is not enough to say we all need to work smarter. We - that is the Northern Ireland Executive - need to decide what our real priorities are because we can no longer afford to deliver the full range of commitments set out in the Programme for Government.
"We will need to make these hard choices now and there will have to be bigger cuts elsewhere. Economy or health and education? Even that choice is not a straightforward one because public sector spending in social policy areas directly affects our economy."
The minister is on record as warning that deferring water charges in 2011 could cost the Executive up to £420 million. And in a further message to fellow ministers, he said: "In my role as Finance Minister, I often hear calls for more funding for projects within individual ministerial portfolios. What I rarely, if ever hear, is a mature discussion on where this funding should come from.
"Following the Chancellor's announcement of last week, it is clear that the predicted period of public spending cuts is no longer something coming down the tracks - it is here now, today. As such, this will necessitate measured debate in the coming months on how the Executive can use its resources to best effect."
But Brian Campfield, general secretary of the public sector union Nipsa, said: "All the political parties have pledged that they are opposed the introduction of water charges and Nipsa intends to ensure that all politicians, including Sammy Wilson, keep to their promise.
"There is an alternative to imposing additional water charges. The Northern Ireland Executive should immediately lift the self-imposed cap and freeze on rates, cut back on the money spent on consultants, stop any new public private partnership projects and demand that the UK government immediately collect the billions of pounds from the wealthy that are due in unpaid taxes."