"We'll look at another 50 million litres a day before winter next year, when we've done further upgrading on the water treatment plant. Now that means a big investment of money, we're talking about an excess of $100m."
The extra 50 million litres would be hopefully accessed through a consent that had already been allocated to another party who hadn't used it, he said.
Goff said all other parties involved would agree to the transfer of that consent.
"We're also looking to get another 100 million litres a day if we need it during the winter months," Goff said.
Were that to happen, water for Auckland would be drawn during the winter in order to replenish the region's storage lakes in the Waitākere and Hūnua ranges, he said.
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In return for the much-needed water, a trust would be set up through Watercare to ensure the ongoing health of the river, Goff announced.
"If we're taking a lot more water from the river, we want to put something back to the river, in terms of improving its water quality," he told Du Plessis-Allan.
"It helps the Waikato and it helps us too, because the quality of the Waikato river is pretty bad."
Several million dollars had been earmarked for the trust, though the final amount would be negotiated, he said.
All five parties had entered Wednesday's meeting with differing views, but all agreed on two things, Goff said: the need to protect the health of the Waikato river and the health of the people living in the Waikato and Tāmaki Makaurau.
On Tuesday Environment Minister David Parker referred Auckland's controversial request to take an extra 200 million litres of water a day from the Waikato River to a board of inquiry.
Parker said the sourcing of drinking water for Auckland was nationally significant and the application affected not only Auckland but also other activities in the Waikato and the river itself.
"The inquiry will need to consider the viability of alternatives, including the treatment of storm and/or wastewater," he said.
"Water taken for Auckland from the Waikato already includes treated water from outfalls from storm water and treated wastewater upstream of its take."
The board of inquiry has up to nine months to make a decision, but Parker expected interim solutions like transferring 25 million litres of water a day for the forthcoming summer to be transferred and settled outside of this.
Instead the inquiry would sort through important issues such as whether Auckland should be allowed the 200 million litres of water a day over other commercial users in Waikato, he said.
He said Auckland's drought situation and population growth has given Auckland authorities "a bit of a fright" and everyone including Hamilton City Council was trying to help.
The inquiry comes after the Government, Waikato Regional Council and Hamilton City Council have been working with Auckland and other interested parties over several months to come up with a solution to Auckland's water crisis.
