CHEYENNE, Wyo. (AP) — Wyoming has struck a deal to accept up to $75 million in place of Arch Coal's $486 million in bonding obligations in the state while the company goes through bankruptcy.

Arch's seven mines in Wyoming include Black Thunder, one of the world's largest coal complexes. Bonding helps ensure those mines could be filled in and restored to a natural state should they close.

In Arch's case, an agreement called self-bonding has allowed Arch to show it can cover all potential reclamation costs in Wyoming in exchange for not having to post any bond.

An agreement filed Tuesday in Missouri bankruptcy court would make Wyoming a priority creditor to collect at least some of Arch's bonding costs if necessary.

Environmentalists say such agreements risk leaving taxpayers responsible for mine cleanup costs.