AUGUSTA, Maine — Two Indian tribes and several progressive groups assailed Attorney General Janet Mills on Tuesday for her role in a court fight over tribal water rights, highlighting a key challenge from the left that could harm her 2018 gubernatorial bid.

The Democrat signed onto a brief supporting the state of Washington in its challenge to federal water regulations. The case will be argued next month at the U.S. Supreme Court, but the uproar over it is connected to Mills’ positions in similar, past court fights in Maine.

In a Tuesday letter, leaders of the Penobscot Nation and Passamaquoddy Tribe joined more than 20 progressive groups — including the Natural Resources Council of Maine, the Maine People’s Alliance, Maine Conservation Voters and American Civil Liberties Union of Maine — to blast Mills for “attacks upon tribal fishing rights at home and well beyond Maine.”

Last year, the Penobscot Nation lost an appeal of a 2012 court ruling holding that its reservation includes islands in the Penobscot River, but not the water. Mills’ office is also representing Gov. Paul LePage’s administration in a 2014 lawsuit against the Environmental Protection Agency.

That case centers on the federal government’s disapproval of certain Maine water quality standards, including many that tightened standards on tribal lands and are backed by the Penobscot Nation and the Passamaquoddy Tribe. Maine contends that they’re “arbitrary” and violate Indian settlement acts.

Assistant Attorney General Jerry Reid, who heads the office’s natural resources division, said in a written statement Tuesday that the Washington State case is about a federal order trying to force the state to spend $2 billion on culvert work and “a misreading of a western treaty.”

“Attorney General Mills accepted the unanimous recommendation” of her office’s non-partisan staff when she signed on to the suit, wrote Reid.

Mills has largely been a foe of the term-limited Republican governor and is running to replace him. But she was confronted by Penobscot protesters at a 2017 event in Portland, according to the Portland Press Herald.

Since President Donald Trump took office, Mills has joined Democratic fights against the Republican’s administration, including a lawsuit against the EPA over air standards. She hasn’t backed LePage in many legal pursuits, including a recent bid to toss the Affordable Care Act.

Mills is one of the top-tier candidates in the 10-way Democratic race to replace LePage and qualified Monday for the June primary ballot. Former Maine House Speaker Mark Eves, attorney Adam Cote, lobbyist Betsy Sweet, state Sen. Mark Dion and former state Rep. Diane Russell are also running for the Democratic nomination.

BDN writer Christopher Cousins contributed to this report.

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Michael Shepherd

Michael Shepherd joined the Bangor Daily News in 2015 after three years as a reporter at the Kennebec Journal. A Hallowell native who now lives in Augusta, he graduated from the University of Maine in...