Recently-released figures showing rapidly dropping numbers of Otago long-term ACC claimants over the past year and growing review applications by claimants challenging ACC decisions were a "wake-up call" over ACC's future, Dr Powell said.
"It's like a line in the sand," she said.
"It's reached the point where the person in the street is asking what's going on."
Otago Daily Times inquiries show the number of long-term claimants in Otago fell more than 15%, from 1199 on June 30 last year to 1014 at the equivalent date this year.
This was the biggest one-year change in long-term Otago long-term claimant numbers for at least five years.
ACC officials recently said "long-term claimants" had been receiving weekly earnings-related compensation for a year or more.
The number of reviews of ACC decisions sought by Otago-based claimants rose at least 5%, from more than 430 on June 30 last year to more than 450 at the same stage this year, other figures show.
Dr Powell said the community's faith that individuals would receive their fair entitlement under the scheme had been badly shaken, and ACC had been used as a "political football" for too long, including during recent cost-cutting.
ACC figures indicate national long-term claimant numbers fell more than 3600, or 25%, to about 10,626 over the past three financial years.
Government officials have also highlighted the need to maintain the scheme's financial viability.
ACC officials say the national "long-term claims pool" has been reducing for several reasons, and improved "focused rehabilitation" by ACC within their first year of weekly compensation payments meant fewer people were becoming long-term claimants.
At an Institute of Actuaries of Australia conference in Brisbane late last year, a New Zealand actuary who has worked closely with ACC, said there was "constant tension between the two sides of politics" in New Zealand, which was reflected in the ACC scheme.
Labour governments typically increased access to benefits, but this had been "to some degree reversed" under National, since 2009, given concerns about ACC finances, the actuary said.
In a recent letter to the ACC board, accompanying the latest service agreement signed between the Government and ACC, ACC Minister Judith Collins emphasised the need for the board and management to "rebuild" public trust in ACC and ensure individual claimants received their fair entitlements.
She also expected the board to "monitor carefully the numbers and outcomes" of claims disputes, and wanted to see "more disputes resolved satisfactorily" without the need for formal independent resolution.
Dr Powell noted that a broad agreement between the Government and the Opposition had developed about the way much of the KiwiSaver superannuation scheme was operating.
If public trust in ACC was to be restored, as Mrs Collins had sought, an agreement between New Zealand's main political parties about how ACC would operate in future was ultimately needed, she said.
