The purpose of the Crown Minerals Act was to promote mining of Crown owned minerals for the benefit of the country, and to achieve a fair financial return to the Crown for its minerals, the letter stated.
"Because of this, I am compelled to ensure that plans and policies in geologically prospective regions manage petroleum and mineral activities in a fair and reasonable manner," she wrote.
"My officials at MBIE [Ministry of Business, Innovation, and Employment] have taken an active interest in making sure planning documents don't undermine this position. With my support, MBIE has appealed plans, and policy statements after making submissions."
In a written response to the letter, council chair Rex Graham noted community support behind the plan change, and the region's "duty" to protect its aquifers.
He said most Hawke's Bay residents did not want fracking or oil drilling near the region's aquifers, and did not want any drilling for oil within the 12 mile nautical zone in Hawke Bay.
In her letter Ms Collins wrote of economic benefits of such operations - from jobs, to petroleum production being a Crown source of revenue.
This revenue, she noted, "is invested in public services and infrastructure, some of which benefits the Hawke's Bay region and its communities".
Mr Graham said the council had a "simple position" in regard to these benefits - "We use these aquifers for our drinking water and it is paramount for the health of our people that we vigorously protect these taonga from any potential threat".
"Our region in also famous for producing clean, safe food for customers around the world which produces our wealth and jobs," he said.
"This primary activity with its substantial support services also depend on our clean aquifers and it is the duty of all of us to protect them and our brand."
Resistance to the plan change was not unexpected - councillors said they were prepared to challenge the Government on the proposed prohibition, after 5569sq km of Hawke's Bay's offshore marine area was released for bids for gas and oil exploration activities in March.
The blocks released under the Government's Block Offer 2017 included areas inside the council's 12 nautical mile jurisdiction - despite its submission this be excluded.
This came soon after the council agreed to consider extending the prohibition to cover the coastal marine area.