Bay of Plenty Regional Council is carrying out water quality tests on the Puarenga stream because of complaints claiming the waterway is polluted.
The stream runs below a bridge leading into the Whakarewarewa village - a popular swimming hole for Te Arawa penny divers.
Tūhourangi Tribal Authority member Walton Lee has advised children not to swim there.
Mr Lee has independently monitored the waterway for up to four years. His advice has been repeated by the district health board.
A 2008 report by Bay of Plenty Regional Council found extensive remedial work in the 1990s by landusers including the Red Stag Mill and the district council improved the stream's quality.
The council expects the latest tests for bacteria like E.coli are to be completed by mid-August.
However, Te Manu Kōrihi News reports Mr Lee has been taken to task for going public. He has appeared on television with his claims.
Tuhourangi head John Waaka says the tribe would have dealt with the matter without Mr Lee's complaints on television.
Mr Lee says he raised his concerns with the authority, but his actions reflect his primary concern: the health of the children.