The progeny of northern Minnesota prospectors and miners, Grant Merritt would seem an unlikely choice to head the Minnesota Pollution Control Agency (MPCA) — and an even more unlikely foe of Reserve Mining Co., as he was in the 1970s.

Merritt’s recent book, “Iron and Water: My Life Protecting Minnesota’s Environment” (University of Minnesota Press, 198 pages, $24.95), details with barely a nod to irony how a third-generation Duluth resident with family ties to the discovery of northern Minnesota’s vast iron ore deposits helped put an end to Reserve’s daily dumping of 67,000 tons of taconite tailing waste into Lake Superior.

Appointed MPCA commissioner March 1, 1971, by Gov. Wendell Anderson, Merritt served as the state’s chief environment protector until June 25, 1975.

“My uncle, who lived in East Beaver Bay, on the North Shore, had come to me in 1967 and told me that Reserve was not only dumping 67,000 tons of tailings into the lake every day, but that they were also dumping oily rags and chemicals,” Merritt said.

At the time, Merritt, now 84, was a lawyer and “aspiring politician” living in New Hope. A graduate years earlier of the University of Minnesota Duluth, he had worked for a while in Silver Bay, where he had seen the tailings being dumped.

“At the time, I wasn’t worried about it, because the state permit said the tailings couldn’t be dumped outside a 9-mile zone in Lake Superior,” Merritt said. “I would find out later the state never enforced the permit.”

Now Minnesota is poised again — possibly — to seal agreements that would allow vast new mining operations in the state’s far north, and Merritt’s perspective on the possibilities, and potential problems, of such undertakings is unique among living Minnesotans.

His message: Proceed with caution.

“Sometimes I am characterized as anti-mining, but I’m not,” Merritt said. “I am, however, concerned that the two major companies that want to mine copper-nickel and other metals near Ely and elsewhere in the northeast are foreign-owned and don’t have the best environmental track records.”

Twin Metals Minnesota is one of those companies, and its plan to build a vast underground mine that might operate for as long as 100 years is particularly worrisome, Merritt said.

That’s because its general location near Ely and Babbitt places it on the Boundary Waters Canoe Area Wilderness side of the Laurentian Divide. This means any inadvertent spillage of toxic waste or wastewater from what generally is known as sulfide mining would irrevocably threaten the BWCA, Quetico Provincial Park, Voyageurs National Park, and lakes and rivers up to and including Lake of the Woods — and possibly beyond.

By contrast, another mining company, PolyMet, is planning an open-pit mine near Hoyt Lakes, from which water drains south toward Lake Superior.

Twin Metals and PolyMet say their proposed mines can be operated without environmental damage, while providing perhaps thousands of good-paying jobs.

Skeptics, and there are many, counter that the mere creation of such massive operations in the northeast will generate a “mining industrial complex” consisting of vehicles, buildings, roads, power lines and rail tracks that will transform the region and degrade the BWCA.

If PolyMet and/or Twin Metals are allowed to mine, Merritt said, Minnesotans should be prepared to monitor their operations closely for a century or more, because that’s how long Twin Metals says it might operate on the BWCA’s edge.

The state’s long-running regulatory and legal battles with Reserve Mining underscore the need for continual scrutiny, Merritt said, noting that the first hearings conducted on Reserve’s application to dump tailings into Lake Superior were held in 1947.

Four years later, in 1951, with the permits in hand, Reserve began building a taconite pelletizing plant in Silver Bay, as well as the Peter Mitchell mine in Babbitt and 47 miles of railroad track connecting the two towns.

It would take 18 years and the constant daily dumping of tailings into Lake Superior before a special federal panel concluded “there is presumptive evidence in the record to indicate that the discharge from the Reserve Mining Company endangers the health and welfare of persons (in Minnesota and) in states other than Minnesota.”

Still more time — another 11 years — would pass before, in 1980, an on-land disposal site was completed for the tailings, ending finally their dumping into Lake Superior.

In the years between 1951 and 1980, of course, scores of state and federal politicians, policymakers, mining executives and environmental regulators came and went.

The only constant during the period was the dumping of tailings, which ultimately were proven to threaten fish, water — and people.

“One of my concerns about the present mining proposals is that mining companies come and go,” Merritt said. “They also tend to consolidate. If Twin Metals and PolyMet were to form one large company, they could gain enough political and economic power to expand their mining operations in northern Minnesota still further.

“You just wonder whether these companies will comply with whatever environmental standards will be set. We know what Reserve did. And we know the state never did anything about it. Not for a long time.”