Powys council said the latest phase of work in Talgarth to help protect 19 properties was due to start in March.
However, they say a single objection has delayed the process which has resulted in funding being lost.
Councillor John Brunt said: "We are extremely disappointed and are actively seeking a resolution to the objection."

Son, 24, landed awkwardly during a challenge on Tuesday and will undergo surgery on his right forearm on Friday.
Neither the club nor the Korean FA indicated how long Son will be out for.
Spurs play Paris St-Germain in a pre-season friendly on 23 July and open their Premier League campaign at Newcastle on 12 August.
Son scored 21 goals in 47 games for the north London club last season, as they finished runners-up behind Chelsea in the league.

Saintfiet said Adebayor and two other Togo players - Kossi Agassa and Floyd Ayite - had shown a lack of discipline after they failed to join up with the squad on time as they prepared for their opening Africa Cup of Nations qualifier next weekend.
"I have no problem with the players as individuals," Saintfiet told BBC Sport from Accra.
At the moment they are not part of it, but they have not been suspended and I have no problem with them. The doors are never closed for me because these are players with exceptional quality
"It's their choice not to come to the hotel, not to be part of the group, and that makes the choice for me very easy to say these players are now not able to be part of the national team.
"We ask only to be as one team together, to prepare us for these important games," Saintfiet explained.
Togo take on Liberia in Lome on Sunday 14 June in a Group A fixture that marks the start of their qualifying campaign for the 2017 Nations Cup finals.
The fixture against Ghana on Monday will be a big test for Togo against the recent Nations Cup runners-up as they prepare for the Liberia game.
The absence of Tottenham striker Adebayor, Stade de Reims goalkeeper Agassa and Bastia midfielder Ayite will be a big loss for Togo but Saintfiet claims he was left with little choice saying all three players were absent for much of last week.
"Floyd Ayite and [Kossi] Agassa were only one time in training and Emmanuel [Adebayor] came twice, but for the rest of the time I never saw him.
"So I'm very sad about that because these three players were in my squad of 23, they are important players for the country and I was looking forward to working with them.
"But if they are not able to be part of it and commit to the national team as all the other players - and we have many more players who play in Europe - the rules are the same for everyone."
Despite removing all three players from the squad, Saintfiet - who previously coached Ethiopia, Namibia and Malawi - insists the trio have not been suspended and could still have a future with Togo.
"At the moment they are not part of it, but they have not been suspended and I have no problem with them. The doors are never closed for me because these are players with exceptional quality.
Adebayor's club Tottenham Hotspur gave him compassionate leave twice last season to return to Africa to deal with a personal family feud that the striker has discussed on social media.
Saintfiet , who was appointed last month as coach of the west African nation, acknowledged Adebayor's importance to the Togo set-up.
"A player like Emmanuel Adebayor is unique in Togolese football with his quality and he's a very strong player.
"But again, if a player wants to be part of the team, he has to be with the team, following the rules of the team."

Creighton was riding at Warrnambool on Saturday when was unseated as his horse The Walrus stumbled early in the race.
He was initially conscious but his condition deteriorated at Warrnambool Base Hospital and he was transferred to Melbourne for further treatment.
He remains in intensive care following wrist surgery, Racing Victoria said.
Creighton was formerly based in Britain and rode big winners for trainer Mick Channon.
Former England footballer Channon tweeted: "Some positive news about Eddie Creighton thankfully. A smashing lad."
Work on flood protection in Powys has been stopped due to an objector to the scheme.
[NEXT_CONCEPT]
Tottenham forward Son Heung-min could miss the start of the new season after fracturing his arm in South Korea's World Cup qualifier against Qatar.
[NEXT_CONCEPT]
New Togo coach Tom Saintfiet has removed captain Emmanuel Adebayor from the squad to face Ghana in an international friendly on Monday.
[NEXT_CONCEPT]
Irish jockey Eddie Creighton is "conscious and responsive" after coming out of an induced coma following a fall at an Australian racecourse.