Spectacular views await at new park <br/> Everything about Cottonwood Canyon State Park is impressive. At 252 miles, the John Day River is the second-longest undammed river in the lower 48 states. It is also one of the most productive steelhead fisheries in Oregon. The canyon is home to the largest California bighorn sheep herds in Oregon. The basalt flows came from Idaho and Nevada 15 million years ago and are 4.5 miles deep.October 26, 2013 12:11 p.m. read more..