The defendant had also been issued an infringement notice in 2010 for an effluent discharge and was sent a reminder letter about its obligations in March 2015.
Ms Brewer said the latest offending came to council's attention after a complaint from a member of the public about the irrigator operating in a paddock quite close to a stream.
When council's enforcement officer arrived at the property they found the irrigator had been placed about 20m from two farm drains and a canal, she said.
Effluent was flowing about 20m across land into a farm drain, which flows into a nearby canal about 200m away, which ultimately flows into the sea.
Ms Brewer said the farm worker had left the travelling irrigator operating unmonitored for an extended period of time.
Samples of the discharge where it had entered the drain and canal, plus upstream and downstream, revealed "very high" levels of faecal bacteria unsafe for recreational bathing.
The defendant's lawyer, Lara Burkhardt, argued that the prosecution's sentence starting point was too high as the abatement notice offence was a "technical breach" at worst.
Ms Burkhardt said her client could have challenged the abatement notice, but chose to accept it despite the circumstances of the first and second discharges being different.
Kahu Ma Farms had also taken "significant remedial steps" to address council's concerns.
That included spending $71,000 to increase the sump capacity, decreasing stock numbers and milking only once a day to reduce the impacts on the environment, she said.
Kahu Ma Farms also spent $7,500 to install a failsafe device on the irrigator.
Ms Burkhardt said the latest discharge had been the result of "human error" rather than a deliberate act or a case of reckless.
She urged Judge Kirkpatrick to also take into account the defendant was making its first appearance in the court.
