Flood relief work has been brought forward after the Welsh government announced an extra £5m in funding.
Environment Agency Wales (EAW) said the money means over 1,000 more properties can be protected in Corwen, Denbighshire, among other communities.
But it warns it will need to treble its flood defence budget by 2035 to maintain current levels of protection.
The Welsh government said it is investing £150m in flood and coastal erosion risk management.
Welsh Conservatives said "after a torrid year of bad weather" planning systems should be more robust to ensure flood plains are better protected.
"This important announcement will mean we can do more work to reduce the risk of flooding for more homes," said EAW director Chris Mills.
"We are doing all we can to reduce the risk of flooding."
He added: "We estimate that we will need to treble the amount spent on flood defences by 2035 to maintain the current level of flood protection.
"This is why we are exploring new sources of money to complement the funding we get from Welsh government."
He said the extra money will be spent on reducing the risk of flooding to more than 650 homes and 450 businesses in Wales.
Environment Minister John Griffiths said: "The extra money will also enable construction work on the Corwen flood defence scheme to begin earlier than planned, which is great news for the affected residents and the local construction industry."
Part of the money will also go towards the £28m on-going Colwyn Bay scheme to strengthen existing sea defences over the seafront, protecting properties, the A55 and rail line.
North Wales Conservative AM Antoinette Sandbach said, following extensive flooding in St Asaph and Ruthin in Denbighshire the Welsh government "must reassure the public in north Wales that they have improved their flood management strategies".
She added: "The flooding damaged homes, crippled transport networks and devastated communities.
"The full impact of the 2012 floods is yet to be determined. However communities are still struggling to get back on their feet after a torrid year of bad weather."
Earlier this week the independent Committee on Climate Change (CCC) published its second report for the Welsh government on climate change.
It said the government's budget for "flood management has been maintained in real terms over the current spending review period, making the budget better protected than in England".