[6][7] In his early 60s, Hauser began to rebuild his finances by branching out into the relatively new industry of hydroelectric power generation.

[16][21] The reason for resuming construction was to supply power to the Butte, Anaconda and Pacific Railway and the Chicago, Milwaukee, and St. Paul Railroad.

[25] There were more than 115 buildings at the construction site, including a bunkhouse and dormitories for unmarried men, cottages for married men, a dining hall, a bathing house, storage sheds, garages, a photography studio, school, hospital, and sewer.

[34] Madison Limestone forms much of the surface rock through which the Missouri River flows at Holter Dam.

[35] Holter Lake sits atop the Eldorado thrust fault, which juxtaposes Proterozoic Belt Supergroup Greyson Shale over much younger Madison Limestone and is part of the Sevier orogeny.

The central section of the lake is a narrow, 5-mile (8.0 km) neck, marked at its downstream end by the Gates of the Mountains.

[35] Although the Missouri River once ran swiftly through the Gates of the Mountains, Holter Dam drastically reduced the flow of water so that now the area has almost no current.

[46] In June 1999, Montana Power proposed lowering the level of Holter Lake by 16 feet (4.9 m) for six weeks so that the flashboards could be repaired and replaced.

[29][49] The sale was expected to generate $30 million in taxes for the state of Montana (although MPC said the total would be lower).

[50] Subsequently, in May 2000 PPL announced it would use small steel cofferdams to drain the water around the flashboards and allow their repair without lowering the level of the lake.

[30] In November 2001, citizens of Montana upset with energy price increases announced by PPL sought passage of a ballot initiative that would require the state of Montana to buy all of PPL's hydroelectric dams, including Holter Dam.

While effective at generating electricity, well-designed, and well-engineered, Holter Dam is considered an exceptionally unpleasant structure visually.

Just below Holter Dam is the Blue Ribbon trout fishing section of the Missouri River.

[60] According to Montana wildlife officials, "Holter Reservoir has historically been one of the most diverse and productive multi-species fisheries in the state.

[60] In 1992, "catch-and-release only" regulations were imposed on brown trout to protect the fragile population numbers of these fish.

[63] These pressures led state wildlife managers to implement in March 2002 limits on the catch of rainbow trout on this part of the Missouri River.

[66] In 2009 and 2010, a fungal disease killed large numbers of mature brown trout below Holter Dam.

[3] In January 2011, as part of its management efforts, PPL agreed to donate $1.2 million to fund 41 conservation projects along the Missouri and Madison rivers, which included restoring and increasing riverside vegetation along 4.5 miles (7.2 km) of the Missouri River below Holter Dam and a study of the walleye feeding habits below Holter Dam.

[70] A 2005 proposal by the managers of the Helena National Forest to draw down Holter Lake by 2 feet (0.61 m) in August 2005 in order to repair Coulter Campground near the Gates of the Mountains had fishermen and recreational outfitters angry due to the likely side-effects on the downstream fishery.

[58] Heavy snowpack and spring rains in 2008, however, forced dam operators to increase the flow to 11,000 cubic foot (310 m3) per second.

[60][76] In 2010, the State of Montana proposed a 10-year fishery management plan for 11 sport and 10 non-sport fish species in Holter Lake.

[77] The regulations would have permitted unlimited walleye fishing below Holter Dam as a means of protecting trout from this voracious, nonnative predator species.

[78] Final regulations approved in October 2010 permitted fishermen to catch and remove an unlimited number of walleye from Holter Dam to Cascade Bridge, but limited catches to 20 per day (and 40 in possession) from Cascade Bridge to Black Eagle Dam.

The state also increased the number of walleye caught between Hauser Dam and Holter Dam to 10 daily (although all fish 20 to 28 inches (51 to 71 cm) in length had to be released), and set the yellow perch limit on Holter Reservoir down to 25 per day.

[81] In March 2011, the Montana Department of Fish, Wildlife and Parks (FWP) set no limit on the number of northern pike anglers may take from Holter Lake and the waters just above it.

[81] A month later, the agency said it had completed an environmental assessment of a plan to remove northern pike from the Missouri River and its feeder streams.

[81] In April 2011, the FWP removed all fishing limits on northern pike from the headwaters of the Missouri River to Holter Dam in order to encourage fishermen to eradicate the species.

[83] In December 2011, the state reported improved numbers of trout below Holter Dam due to several high-volume years of cold water in the Missouri River.

[32] Birds of prey can routinely be seen plucking fish from Holter Lake and the Missouri River below the dam.

As part of its federal licensing agreement, PPL Montana donated $1.2 million in 2011 to fund 41 conservation projects along the Missouri and Madison rivers.