Disgust at the timing of an Environment Canterbury decision to let Silver Fern Farms dump waste into the Waimakariri River in rare flooding events.

Independent commissioners have granted a five year emergency consent to the company, following a lengthy hearing process.

Fish and Game's regional manager Rod Cullinane is questioning the motives for releasing the decision just before Christmas.

"I'd go so far as to say it's almost under-hemmed, given that the appeal period will run through to the 10th of January, I understand, which isn't a time that makes it easy for anyone considering an appeal to do so."