Park Overview Hat Rock State Park, located off U.S. Highway 730 nine miles east of Umatilla, lies on the south shore of Lake Wallula behind McNary Dam on the Columbia River. Hat Rock was the first distinctive landmark passed by the Lewis and Clark Expedition on their journey down the Columbia, and is one of the few remaining sites not underwater. The park is a desert oasis surrounded by rolling sagebrush hills and outcroppings of basalt. This special place offers visitors a chance to escape the summer heat under the shelter of cottonwood and black locust ringed by acres of green grass. A boat

Sources: Wikimedia Commons / editorial, State agency · updated 2026-08-23