The $33,520 penalty imposed on Forest Owner Marketing Services was a result of its forest harvesting operation on land south-east of Ōpōtiki.
Two contractors employed by the company were also fined. Gaddum Construction Ltd received a $15,000 penalty and Chance Brown was fined $10,500.
Between October 2014 and May 2015, workers were carrying out harvesting and earthworks in a pine forest at Tirohanga.
A member of the public alerted Bay of Plenty Regional Council to sediment in a stream south of the forestry block.
The council said its investigation revealed poor environmental management during the harvesting had left the site prone to erosion and sediment discharges.
The council raised its concerns with Forest Owner Marketing Services several times but it said the company failed to take adequate steps to address those concerns. Several months after the council first highlighted the issues a large landslide of sediment and forestry debris occurred.
The council paid an independent contractor to carry out remedial work in the forest at the end of 2015 at a cost of about $17,000. Forest Owners Marketing Services has undertaken to reimburse the council.
The council said damage to the streams in the forest was exactly what the consent conditions were designed to avoid.