Before Matt Mendes guided on the Deschutes River, he drove the Green Monster. It was 2002, and Mendes was 13 years old; the job was his first on the river. The Green Monster, an old Ford F350, nicknamed for its paint job, belonged to his maternal grandfather, Al Bagley, a revered fly-fishing guide and a member of the Confederated Tribes of Warm Springs. The tribe governs the 1,019-square-mile Warm Springs Indian Reservation, located in Oregon’s high desert and bound to the east by the Deschutes, one of the country’s premier steelhead and trout destinations. In 1997, Bagley became the tribe’s first fly-fishing guide, capitalizing on its exclusive access to 22-miles of the Deschutes’s west bank, per an 1855 treaty with the United States government. The business was gangbusters from the get-go.