The Green Party says the Department of Conservation's final submission on the proposed Ruataniwha dam in Hawke's Bay shows the Government's bias against the environment.
A draft submission prepared by department staff said the dam was risky, and could make the Tukituki river toxic, but that criticism was not included in DoC's final submission.
Green Party co-leader Russel Norman has accused Conservation Minister Nick Smith of compromising the advocacy role of the Department of Conservation.
The Greens are concerned the Minister gagged DoC after it emerged its report on the Ruataniwha dam was reduced from 32 pages to two paragraphs, after misgivings about the dam's water management plan were removed.
Dr Norman told Radio New Zealand's Morning Report that in effect, Dr Smith is saying that DoC can't put in a strong submission in such cases because that would put him in a difficult position as he makes the final decision.
Greens conservation spokesperson Eugenie Sage says no one at the Government level is speaking out for the public interest and protecting the country's rivers.
"The regional council isn't because it's promoting the scheme, MPI's promoting irrigation, and DoC - which could've given technical independent evidence around water quality - hasn't been allowed to make that submission."
Ms Sage says DoC has a statutory responsibility to advocate for conservation.