A Rotorua iwi trustee is calling for stricter rules for firms disposing of waste into water that runs into a penny-diving swimming hole at Whakarewarewa Village.
The Bay of Plenty regional council is carrying out tests for bacterial contamination of the Puarenga stream following complaints.
The stream flows beneath a bridge that leads into the Whakarewarewa Village, where the people of Tuhourangi and Ngati Wahiao have lived for more than 200 years.
In July, the local health authority advised children not to swim in the stream, and the council says testing shows that the water quality is poor.
A trustee for Tuhourangi Tribal Authority, Walton Lee, says companies such as the Red Stag Timber Mill are complying with their resource consents, but they could be doing a lot better.
Red Stag says it is already maintaining high standards in its disposal of effluent.