Downstream water samples showed ammonia was present at 90 times the allowable levels.
Hawke's Bay Regional Council launched an investigation, which led to the issuing of a public warning not to swim in the popular swimming spot for a week.
The council became aware only when a member of the public informed the pollution response team that a stream was "running green", according to HBRC lawyer Nicola Graham.
At an Environment Court hearing last year, Graham claimed the incident was a direct result of a failure by management to ensure the correct processes and training were in place.
She cited environmental, societal and cultural impacts from the incident, and said the company's actions were "reckless in the least".
She noted that employees of the company had been issued with infringement notices twice since 2015 for dairy effluent offending.
At the time of the trial, Maxwell Farms Limited's lawyer Simon Connolly said while "regrettable", the offending was primarily down to "human error".
Connolly said management was unaware the staff member, who is no longer the farm manager, had not received formal training.
HBRC group manager policy and regulation Katrina Brunton says the local community has sent strong signals to the council that it values clean water.
"To uphold these values, we are committed to enforcing the rules to protect the health of our environment and our community. The penalties applied by the court should deter this type of offending," she said.
"The Tūtaekurī holds significant cultural value to local iwi and is used for recreational activities. This incident forced the closure of a popular swimming hole in the river for a week, which meant families were unable to enjoy using it over the summer holiday period."
