Ngati Rangiwewehi say they have "absolutely sought legal advice" over the legality of a proposed fee at Hamurana Springs.
The iwi announced the new entrance fee last month.
People were quick to share their opinion on social media with some saying the recreational reserve status of the Springs meant the fee was illegal.
Hamurana Springs was classified as a recreation reserve in the 2014 Ngati Rangiwewehi Claims Settlement.
Under the Reserves Act 1977 a charge is not allowed to be placed on the use of a reserve for more than 40 days of any year without the prior consent of the Minister of Conservation.
The spokesman for the Te Kaikaitahuna Management group, the business arm of Te Tahuhu o Tawakeheimoa Trust which is representing Ngati Rangiwewehi, Russell Harrison, said they had sought legal advice regarding their plans for the Hamurana Springs Reserve.
"The fee we intend to administer, under Sections 53, 54 and 58 of the Reserves Act, is a management fee for maintenance and upkeep of the reserve including the platforms, walkways, bridges, amenities, carparks and conservation efforts.
"The operation model is similar to a number of other tourism ventures that operate on reserves," he said.
"We are deeply committed to our role as landowners and kaitiaki of Hamurana and this is at the forefront of all of our decisions.
"Caring for Hamurana costs money so to help us absorb these costs we have decided upon a surcharge."
Ngati Rangiwewehi have yet to confirm the cost for entry into the reserve.
"As an iwi, Ngati Rangiwewehi is looking forward to returning Hamurana back to its former glory as this is part of a bigger plan to help achieve our iwi vision which is to maximise the potential of our people and land for generations to come," Mr Harrison said.
"We understand that some will disagree with our choices but we believe we are pro-actively utilising Ngati Rangiwewehi assets to grow iwi sustainability for the betterment of tomorrow's generation."
The Department of Conservation is working through a five-year restoration and transition plan with Ngati Rangiwewehi.
Operations manager Jeff Milham said the department did not want to prejudice discussions with Ngati Rangiwewehi and commenting publicly was inappropriate at present.
"The department is confident in Ngati Rangiwewehi's ability to manage the reserve and will continue to offer its support through until 2019."
Department of Conservation senior community ranger Margaret Metcalfe said they had no reason to believe Ngati Rangiwewehi would not be able to maintain the Springs to the same or a higher standard than the department.