Wyo. Stat. Ann. § 41-11-101

The attorney general shall be the legal advisor to the commission and it shall be his duty to defend any suit or suits that may be instituted against the state of Wyoming, or against the water users and appropriators from this state, by the United States government, or by any other state, involving the question of priorities and rights of interstate streams; or if advisable to prosecute any suit necessary to properly safeguard the interests of the state or its citizens, in such interstate streams.