But Green Party water spokesperson Eugenie Sage said yesterday the latest email made it "increasingly hard to believe the Minister's claims" that he had not had any influence on the department's submission.
In Parliament yesterday Dr Smith referred to an earlier statement by Dr Johnston on the matter where she said: "The Minister did not play any role in my decision making. He gave no direction. He never told me his view."
Dr Smith said documents released by the department showed "before the department even met with me there was a departmental senior official recommending a neutral submission".
While he had requested to see the submission, it was "absolutely proper" for a minister to ask his department to provide a copy of a submission before a board of inquiry, and an explanation as to its contents.
"I would love to show the member the hundreds of pages of submissions that were approved by previous Ministers under the Labour Government on equivalent boards of inquiry," he said.