The giant dairy cooperative Fonterra is the latest to be penalised for polluting a waterway.
The company has been fined $24,000 in the Tauranga District Court for a chemical spill at its Edgecumbe milk processing plant last year.
The spill caused nitric acid and a caustic cleaning agent to end up in a stormwater drain.
Three Bay of Plenty farmers have also been convicted this month for breaching effluent discharge conditions, with fines ranging from $12,000 to more than $26,000.
The Bay of Plenty Regional Council says the fines are a timely reminder to all dairy farmers that they must comply with resource consent conditions for effluent discharge.
It says all three dairy farm cases were a result of poor management of effluent systems, including ponds and irrigators.