Rimrock Lake, located in Harney, Oregon, is a privately owned earth dam built in 1905 primarily for irrigation purposes. With a height of 10 feet and a length of 200 feet, this dam holds a maximum storage capacity of 200 acre-feet and covers a surface area of 134.6 acres. The reservoir's drainage area is 4.6 square miles, with a maximum discharge capacity of 75 cubic feet per second.

Despite being classified as having a low hazard potential, Rimrock Lake is regulated and inspected by the Oregon Water Resources Department. The dam features a slide gate as its outlet gates and has not been rated for its condition assessment as of the last inspection in June 2017. The surrounding area does not have any downstream settlements, adding to the remote and natural beauty of the location.

For water resource and climate enthusiasts, Rimrock Lake offers a glimpse into early 20th-century water management practices and the vital role of irrigation in agricultural areas like Harney County. The dam's historical significance, combined with its peaceful and undisturbed setting, makes it a noteworthy site for those interested in water infrastructure and its impact on the surrounding environment.