BOISE, Idaho (AP) --Federal land managers have determined Monsanto Co.'s proposed new Idaho phosphate mine near Soda Springs will release no detectible selenium into the Blackfoot River.

Public comment on the preliminary plan for the Blackfoot Bridge Mine, to produce raw materials for the St. Louis-based company's Roundup herbicide, runs through Sept. 28.

Last year, Bureau of Land Management officials determined Monsanto's original mine plan would result in federal Clean Water Act violations.

As a result, the BLM is insisting Monsanto use an underground liner to prevent rain and snow melt out of selenium-rich waste rock and leaking downstream.

Monsanto says it favors the liner proposal, which adds $25 million in costs.

The Greater Yellowstone Coalition, an environmental group, is having a consultant analyze the proposal.