THE Fisheries Department is seeking legal advice after Wide Bay Water decided not to build a fishway on the Burrum River No. 1 dam at Howard.

A Fisheries Queensland spokeswoman said the department wrote to WBW in April last year "seeking advice as to how they intend to meet their commitment to improve fish passage in the Burrum River".

"No response has been received to date," she said.

"We are currently seeking legal advice concerning this matter."

WBW chief executive Peter Care confirmed the board had received the letter.

"My only comment is the board has made a decision not to take it any further," he said.

In September 2010, WBW committed $3.2 million to building a new fishway with an expected completion date of June 2013 but the deadline passed and in April last year, the WBW board decided not to go ahead because of the cost.

At the time, WBW chairman Cliff Searle said the money would be better spent on other infrastructure.

He said despite earlier reports, there was no condition on WBW to build a new fishway when Lenthalls Dam was raised in 2007.

A Fisheries Department spokesman at the time said the board's decision contradicted previous written correspondence in which WBW committed to construction.

Wide Bay Burnett Environment Council president Roger Currie said a fishway was needed to sustain the fish population because some species needed to head up from the saltwater into the fresh.

"Ecologically we do need to do something about fish passage on the Burrum," he said.

But Mr Currie said he believed the commitment to build a new fishway was a gentleman's agreement between WBW and the Fisheries Department and the corporation hadn't been tied to a legal obligation.

Mayor Gerard O'Connell said discussion on the issue had probably been exhausted.

"It's been dealt with," he said.

"The board's made a decision."