BUTTE, Mont. (AP) — The U.S. Supreme Court will decide whether residents of two Montana communities can continue their decade-long effort to get the Atlantic Richfield Co. to pay for a more thorough cleanup of arsenic left on properties after a century of copper smelting.

The Montana Supreme Court ruled in December 2017 for the residents of Opportunity and Crackerville.

They sued in 2008 seeking to force Arco to reduce arsenic levels to the area's normal level, 25 parts per million.

The U.S. Environmental Protection Agency said cleanup was required when arsenic levels were above an "acceptable" level of 250 parts per million.

Arco appealed to the U.S. Supreme Court, arguing federal law prohibited state lawsuits from interfering with an ongoing cleanup.

The Montana Standard reports the justices agreed Monday to hear Arco's appeal.

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This version corrects that cleanup was ordered when contamination was above 250 parts per million, not that cleanup was ordered to level of 250 parts per million.

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Information from: The Montana Standard, http://www.mtstandard.com