The Government is being urged to investigate "how Auckland City got itself into its current predicament", as the region's council pushes to double the amount of water it takes from the Waikato River to address its major shortage.
Auckland has suffered a once-in-a-generation drought over the last few months, but critics of the council say the lack of rainfall has just exposed incompetence in the face of crisis and a lack of forward-planning.
Auckland Council has applied to Waikato Regional Council to draw an extra 200 million litres of water a day from the river, but the application is in a long queue. Under the Resource Management Act (RMA), councils are legally obliged to address each application chronologically.
Pressure is now building on the Government to amend the RMA to allow the application to be pushed to the front of the queue - but the Waikato River Authority (WRA) says Auckland Council has put itself in a tricky position, and is too reliant on neighbouring Waikato to come to the rescue.
"This will remove a significant volume of water from the Waikato River catchment, lower the river across a wide area, and risk further intrusion of salt water into the river system with consequential ecosystem and habitat effects," WRA iwi co-chair Roger Pikia said.
"Auckland last year took 17 percent of its water needs from the Waikato River, and is currently taking an estimated 40 percent. It is not sustainable for more and more water to be going out of the Waikato catchment.
"This is not a Waikato versus Auckland issue, this is a Waikato River issue."
The WRA is now asking Nanaia Mahuta, the Minister for Local Government, to launch an independent inquiry into how Auckland's water infrastructure crisis came about.
Crown spokesperson Dylan Tahau says the WRA needs to understand the reasons behind Auckland Council's request "because the Waikato River now appears to be central to Auckland's future water needs".
"It is our view that a failure of leadership and forward planning has led to Auckland City's water crisis," a joint letter from Pikia and Tahau to Mahuta explains. "The drought has put a spotlight on these failings rather than being the sole cause of the water shortage.
"With the Auckland Mayor claiming thousands of job losses and a national economic impact arising from this crisis, we believe it is entirely prudent for a Government inquiry to independently assess how Auckland City has got itself into its current predicament."
Raveen Jaduram, the chief executive of Auckland Council-owned Watercare, says he won't resign despite frustrations over the city's water crisis.
He told The AM Show water is "vital" for the Auckland economy - which in turn means it's vital for New Zealand.
"Water should go to the most productive use and we believe that Aucklanders are very efficient water users," he explained on Monday morning.
"Water is vital for the economy - it is not helpful if we sway away from the facts and the facts are, Aucklanders are very efficient water users."