Minnesota will keep, for now, an existing rule imposing limits on manganese in drinking water.
The Minnesota Department of Health was proposing to weaken the rule, but reversed course after receiving public comments.
One of those comments came from Paula Maccabee at the environmental group Water Legacy.
"We're very pleased that the Minnesota Health Department has listened to Water Legacy and other citizens of Minnesota, and is keeping in place Minnesota rules that protect children and elderly persons," Maccabe said. "We think that's a very positive step."
About 30 individuals and public interest groups protested, pointing to a health effects study published in September.
At small dose, manganese is good for us, but in larger amounts it can harm the nervous system. The Health Department was planning to adopt a looser federal standard, until it could study the problem thoroughly.
Paul Moyer from the Health Department said the agency listened to the public.
"Those concerns were strongly supported by that additional scientific information," Moyer said.
Now, Moyer said the Health Department will begin a study of manganese next year.
Manganese is one of several minerals expected to be released at high levels from proposed copper-nickel mines in northeastern Minnesota.