United States, Minnesota, Marshall, Thief Lake Wildlife Management Area. Marshall Co. Thief Lake Wildlife Management Area; 3.6 mi N of the jnc. of Rt.6 and rt.89 (on the E side of Rt.89). T158N Marshall Co. Thief Lake Wildlife Management Area; 3.6 mi N of the jnc. of Rt.6 and rt.89 (on the E side of Rt.89). T158N R39W Sec.30. 158N 39W 30