Iwi are calling on Far North power company Top Energy to monitor Ngawha's hot springs and to foot the bill for a thermal pool upgrade if it gets permission to expand its nearby geothermal power plant.
Top Energy is applying for consents from the Northland Regional and Far North District councils to triple the output of its Ngawha power station, east of Kaikohe, from 25MW to 75MW. Hearings took place before a panel of commissioners last week in Kerikeri.
If the proposal goes ahead, it would make the Far North energy self-sufficient. The company says it could also create hundreds of jobs in industries attracted by cheap power and heat.
Ngawha's geothermal field, however, also feeds hot pools with considerable cultural significance to Ngapuhi.
On Thursday, representatives of the Parahirahi C1 Trust, which owns part of the land under the Ngawha Waiariki hot pool complex and has a claim on the rest, urged commissioners to refuse consents.
If the expansion went ahead, the trust called for strict monitoring of the springs to make sure the power station did not affect the composition, temperature or pressure of the water.
The trust also wanted full membership of the peer review panel and staging of the project over a five-year period.
Trustee Amokura Kawharu, a law lecturer at Auckland University, told the hearing the hot springs had been known for their curative powers, as well as for cooking and heating, since the 16th century.
No natural resource had greater significance to Ngapuhi than Ngawha Waiariki and the springs.
Ms Kawharu also called on Top Energy to provide "material cultural benefits" to balance the negative cultural effects of exploiting the geothermal field.
She proposed the company meet the costs of a planned upgrade to the hot pool complex as a return benefit to the trust for the people it served.
Top Energy is not commenting until the hearings are complete. The commissioners are expected to release their decision next month.
Early last year, the Parahirahi C1 Trust disclosed plans for a $2.5 million upgrade of the pools, including a revamp of the rundown facilities and a barrier to protect the complex from floods.
As part of its expansion plans, Top Energy has bought the adjacent farm and Ginns Ngawha Spa, another hot pool complex across the road from Ngawha Waiariki.
Ginns is currently closed for renovation.