Hills Creek Reservoir, also known as Hills Creek Lake, is an artificial impoundment behind Hills Creek Dam on the Middle Fork Willamette River in the U.S. state of Oregon. The lake is near Oakridge in Lane County about 40 miles southeast of Eugene, at the confluence of Hills Creek with the Middle Fork. The reservoir and its watershed lie within the Willam…Hills Creek Reservoir, also known as Hills Creek Lake, is an artificial impoundment behind Hills Creek Dam on the Middle Fork Willamette River in the U.S. state of Oregon. The lake is near Oakridge in Lane County about 40 miles southeast of Eugene, at the confluence of Hills Creek with the Middle Fork. The reservoir and its watershed lie within the Willamette National Forest.