The officers observed two orchard sprayers operating in gusty wind, with spray clearly seen blowing over the path and Otene Rd, despite not having any signs on the pathway that spraying was in progress.
The agrichemicals the cyclists came into contact with were Calibra (a fertiliser), Folicur (a fungicide classified as hazardous), Mantrac (a fertiliser classified as hazardous) and Pristine (a fungicide classified as hazardous).
Judge Melinda Dickey fined the company $14,000 for the breach of the Hawke's Bay Regional Resource Management Plan.
HBRC group manager policy and regulation Katrina Brunton said the large fine serves as a strong signal to orchardists that they must comply with the law.
"Sprays can be dangerous to public health and need to be used with great care and diligence," she said.
"We will not tolerate poor practice from the horticulture sector, and will rigorously enforce the law to protect people and the environment."
Brunton said the fine should discourage others from not taking the proper precautions when using agrichemical spray.
"This is the fourth successful prosecution for the regional council this year. We are committed to pursuing illegal activities through the courts to enforce the rules that protect our community and our environment."
Anyone with information regarding unauthorised discharges to land, air or water should contact the council's 24/7 Pollution Hotline on 0800 108 838.