Senior councillors and Welsh Assembly local government secretary Peter Law complained about the impact the Assembly's arrival has had on local government.
Polls indicate nearly half the Welsh public think the Assembly has achieved nothing, said City & County of Cardiff lord mayor, Russell Goodway.
Local authorities spend too much time implementing the policies of central and regional government, rather than addressing the priorities of the electorate, he told the WLGA conference in Llandudno.
'The attitudes among politicians in Wales towards their colleagues in other tiers of government are remarkably immature to the extent that, in my view, it threatens the cohesive governance of our country.'
He called for an overhaul of the political system in Wales, suggesting the population of 2.9 million was over-governed by 1,500 councillors, 60 Assembly members, 40 MPs and five MEPs.
Mr Law warned he would be looking for greater co-operation between the branches of government.
'The Assembly expects much greater joint working between its agencies, local authorities and others to make things happen,' he said.
'It is still a young institution but its philosophy is clear. Partnership, in particular with local government, business and the voluntary sector, is inherent in the Government of Wales Act and underpins the Assembly's own policies.'
Peter Black, the Liberal Democrat local government spokesman in the Assembly and a member of City & County of Swansea Council, said councils are being forced into short-term emergency measures because of a lack of long-term planning to tackle crime.
'Up to 25 years sustained action is needed to tackle crime, drug and alcohol abuse, poor health and a poor skills base - otherwise the Assembly will have failed. Short-term grants make it very difficult to institute change and policy initiatives need to be properly funded,' said Mr Black.
Wales has a backlog of£750m in council house repairs and a quarter of a million people live in unfit housing. Public transport is rare and expensive and it is nearly impossible to find affordable childminders while parents go out to work, he added.