The committee is scheduled to begin hearings later this month, but the group will proceed without Cohen.
Six lawmakers say DEC Commissioner Larry Hartig removed Cohen from the panel because he was a clean water advocate.
They also say Cohen's dismissal was the result of pressure from the cruise ship industry.
Sens. Hollis French and Bill Wielechowski and Reps. Beth Kerttula, Mike Doogan, Berta Gardner and Les Gara want Gov. Parnell to reinstate Cohen to the panel.
"That is not how we should be doing business in the state of Alaska. The state of Alaska, when we're talking about positions that deal with sensitive environmental issues, the protection of Alaska waters, the protection of Alaska lands we should not be letting industry dictate who's on commissions, who's on panels—absolutely, positively not," said Wielechowski, D-Anchorage.
Last week Hartig told the Alaska Public Radio Network that he wants a panel for independent experts, not advocates.
Hartig's office said simply that he and the governor will review the letter.
Parnell's spokesperson says the governor supports Hartig's review to find an unbiased panel.
Wielechowski said that he had a conversation with Hartig last week in which Hartig said he dismissed Cohen for his advocacy.
Wielechowski also says Hartig told him that people within the cruise ship industry had been calling to complain about Cohen.
Contact Ted Land at firstname.lastname@example.org