DULUTH – The environmental movement in northern Minnesota has added an influential force to its ranks: tribal leaders.

Through a series of legal victories, including one just weeks ago, tribes are extending the meaning of rights they reserved in 19th-century treaties. Earlier court battles established that tribal members have the right to hunt, fish and gather on vast tracts of land they ceded to the federal government. Now, the tribes are asserting that the treaties mean there must be fish in the rivers to catch, game on the land to hunt and wild rice in the lakes to gather.

This argument could lead to far more comprehensive protection for the waters and land that have sustained them for generations.

"We are not only trying to preserve the diminished resource we have now, but we're also asserting that these waterways deserve to have their original chemistry restored," said Karen Diver, chairwoman of the Fond du Lac Band of Lake Superior Chippewa. "How do we craft approaches to put habitat back that used to be there? How do we heal what we've done to it over time?"

That's a tall order in a part of the state that is always desperate for jobs, and is now the focus of several companies wanting to dig mines for copper and nickel.

The tribe's latest victory came when the federal Environmental Protection Agency admitted it had made a mistake in approving a state-granted variance that allowed Mesabi Nugget to exceed water quality standards at its Hoyt Lakes plant, which produces high-purity iron nuggets.

The two Chippewa bands and two environmental groups that sued the EPA — Fond du Lac Band, Grand Portage Band, Minnesota Center for Environmental Advocacy and a small group called WaterLegacy — have been focusing on some of the same issues lately, and the strategic cooperation has proved effective.

"If the agency looks at a mining company, and doesn't see anyone on the other side, it's easier to waive rules, easier to give variances," said WaterLegacy attorney Paula Maccabee. "If somebody else also is watching the process, it keeps the regulators honest."

Several tribes are in the throes of high-profile environmental battles. The Bad River Band in Wisconsin is fighting a proposed new taconite mine in its ceded territory; the Keweenaw Bay Indian Community has long opposed the Eagle copper-nickel mine, under construction in Michigan's Upper Peninsula.

In Minnesota, tribal water quality experts are watching the ongoing environmental review of PolyMet Mining Corp.'s proposed copper-nickel mine near Ely. Tribal authorities have a long list of topics on which they say the PolyMet review is still inadequate. In earlier critiques, the state relegated their concerns to footnotes; tribal experts are hoping for a more thorough response this time.

Tribal staff members also serve on an advisory committee that oversees research on the impact of sulfate pollution on wild rice — a major effort that could ultimately force mining companies and other industries to install expensive wastewater filtration systems.

Most tribal leaders say they would rather avoid costly litigation. Diver said she wants to focus on pollution prevention.

"Prevention is cheaper than restoration, and restoration may not always be possible." she said. "We can't always undo what we've done."

Stephanie Hemphill is a freelance writer based in Duluth.