Former Australian Federal Police commissioner Mick Keelty has been the interim inspector-general since October last year.

Water Minister Keith Pitt announced last week the substantive role would be merged with the Murray-Darling Basin Authority's compliance functions under new legislation.

Opposition water spokeswoman Terri Butler said the inspector-general's role had no enforcement powers without a bill passing parliament.

"Australians were promised a cop more than a year ago but to date we remain copless," she told the Murray Darling Association's conference on Tuesday.

Ms Butler said the merger made sense but criticised the government for being too slow to implement the Productivity Commission recommendation made almost two years ago.

She said the government planned to implement the new cop by September 2021.

The Brisbane-based MP cited a slew of basin reports that found communities are losing faith in governments' ability to act on water policy.

"Increasing transparency is an important aspect for any moves to fix the erosion of trust," Ms Butler said.

"The broader question of loss of trust and confidence is an issue that is particularly worrying."

Labor is refusing to release detailed policy until closer to the next federal election, due by 2022.

But Ms Butler indicated she would be open to considering proposals to give local government more say on basin issues.

Australian Associated Press