Holter Lake reservoir was formed by Holter Dam on the Missouri River. It was finished in 1918 by the Montana Power Company for power generation. Upper Holter Lake is separated from the main reservoir by a narrow section in the Gates of the Rocky Mountain canyon. Holter Lake is a very popular lake, both for fishing and for pleasure boating in Montana. The lake has very good fishing for rainbow trout, as well as walleye, perch, brown and kokanee salmon. Perch hug the shoreline, while open-water trout and walleye mill around on the sandy flats.

Hydroelectric development is a significant component of the history of the Gates of the Mountains. Holter Dam, located approximately 7 miles north of the northern mouth of the Gates of the Mountains, was constructed beginning in 1910. The construction of this dam inundated lands witching the Gates of the Mountains canyon. Construction of the Holter Dam was carried out over an eight-year period. The camp associated with the dam construction was extensive and included a photographic studio, school, blacksmith shop, boarding house, store, barber shop, gardens, hospital, bunkhouses, and single family residences. The number of workers housed at the camp varied between 400 and 725 and included engineers, skilled mechanics, artisans, and common laborers. The area that housed the Montana Power Company (MPC) employees was separate from the foreign laborers camp with the MPC camp being very elaborate. Heritage survey work conducted the Holter Dam construction camp indicates that the remains of over fifteen original structures still exist. The Gates of the Mountains area is currently managed as a recreation corridor. The Montana Department of Natural Resources and Conservation, the USDA-Helena National Forest, and the USDI-Bureau of Land Management, manage the area collectively. As part of management of this area, these three agencies interface with Pacific Power & Light-Montana (PPLM), formerly the Montana Power Company,(MPC), regarding the management of resources within the corridor.

Because the river corridor is a reservoir created by the construction of Holter Dam, PPLM, as required by its permit with the Federal Energy Regulatory Commission (FERC), is responsible for damage to resources located within the high water level of the river. The FERC license for seven hydroelectric facilities, including Holter and Hauser Dam, was issued in 1956. Intensive heritage survey and test excavation work conducted in the 1990s was accomplished as a requirement for the recent re-licensing of these facilities.