POCATELLO, Idaho (AP) -- The public comment period for a proposed new phosphate mine in southeastern Idaho has been extended by a month to the end of October, to give more people a chance to weigh in.

Monsanto Co. intends to mine phosphate ore from its Blackfoot Bridge site to supply raw materials for its weed killer Roundup.

The mine would replace Monsanto's South Rasmussen Ridge Mine, which federal regulators say is leaking selenium and heavy metals into tributaries of the Blackfoot River. Other mines in the region have been blamed for killing livestock poisoned by selenium.

But the Bureau of Land Management has determined Monsanto's plan for the Blackfoot Bridge mine, including a roughly $25 million liner for its proposed waste dump, will eliminate detectible selenium leaks.

The extension announced this week pushes the end of the comment period to the close of business on Oct. 31.

On the Net:

-- Copies of the Blackfoot Bridge draft environmental impact statement, as well as an opportunity to comment, are at http://www.blm.gov/id/st/en/prog/0.html.

Copyright 2009 The Associated Press.