A judge has described the actions of those running a Cambridge dairy farm as careless, inattentive and irresponsible over developments on its land.

The business has been fined a total of $26,000 for a range of offences.

They include illegally disturbing the beds of a watercourse and a stream, and disturbing the bed of a wetland.

Hamilton District Court judge Craig Thompson said he was mystified that J and J Watt Limited had sought and obtained an appropriate consent but then completely failed to take account of its conditions.

A prosecution was brought by the Waikato Regional Council after it inspected the farm last year and discovered recent earthworks around watercourses that ultimately led to the Waikato River.

It says the farm's actions significantly increased sediment loads in the stream flowing through the property.