in this Island on a Cottonwood tree an Eagle has placed her nest; a more inaccessible spot I believe she could not have found; for neither man nor beast dare pass those gulphs which separate her little domain from the shores.

[23][24] In 1872, Thomas P. Roberts, a survey engineer for the Northern Pacific Railway, formally named the cataract "Black Eagle Falls" after the incident recorded in Lewis' journal.

Railroad magnate James J. Hill organized the investors, who were primary owners of large amounts of stock in the Great Northern Railway.

[28][29] Gibson realized that the Great Falls of the Missouri could provide abundant, cheap electricity for industry, and proceeded to promote the town on this basis.

The company immediately began purchasing riverside land and water rights along the Missouri River from Black Eagle Falls down to Sheep Creek (a distance of about 12 miles (19 km)).

[35] GFWPTC engineers designed a rock-and-timber crib weir overflow dam,[4][31] in which dressed and shaped heavy timbers formed a closed structure filled with rock or rubble.

[44] The island and the north bank of the Missouri River formed the tailrace (or channel for water leaving the powerhouse) of Black Eagle Dam.

[45] The north bank and a masonry wall offshore formed a long, concrete-lined forebay (100 feet (30 m) across at its widest part) for the northern powerhouse.

[63] The Boston and Montana smelter toppled four fully loaded railroad cars into the Missouri just north of Black Eagle Dam in an attempt to divert the floodwaters from the plant.

In 1908, John D. Ryan (president of the Daly Bank and Trust Co. in Butte and the Anaconda Copper Company, and a future Assistant Secretary of War)[66] purchased most of the shares in the GFWPTC.

[67] In 1910, GFWPTC organized a subsidiary, the Great Falls Power Co., to take over ownership and operation of Black Eagle Dam and its other hydroelectric properties (then being built).

By the early 1920s, the needs of the city of Great Falls had outstripped Black Eagle Dam's ability to generate electricity, and the smelter was planning a new electrolytic zinc manufacturing plant that would require 10 MW of power.

[45] Concrete and masonry retaining walls north and south of the powerhouse were also built to help prevent erosion of the riverbank into the forebay and tailrace.

[94] For security reasons, the Montana Power Company closed the dam to such foot traffic during World War II and never allowed it to resume afterward.

[96] After almost a decade of extensive research and data collection as well as unfruitful negotiations, a hearing began before an FPC trial examiner on November 18, 1946, to determine whether the rivers where Montana Power had constructed dams prior to 1935 were navigable and therefore should be licensed under the act.

"[101] The court of appeals held that Black Eagle, Morony, Rainbow, and Ryan dams were on navigable waters and occupied public land without any authority.

[102] Montana Power appealed the decision to the Supreme Court of the United States, which denied certiorari (refused to hear the case) in March 1951.

(Black Eagle dam was relicensed by the Federal Energy Regulatory Commission, the successor agency to the FPC, on September 27, 2000 for 40 years.

[106] The sale, which included Black Eagle Dam,[107] was expected to generate $30 million in taxes for the state of Montana (although MPC said the total would be lower).

In June of that year, PPL Montana initiated a $55 million effort to replace overhead power lines connecting the dam to the area's electric grid.

[115][116] Black Eagle Dam (which slows the water and allows sediment to fall to the bottom of the reservoir) has been listed as one of the contributing sources of this problem.

Driftwood and logs are the most common forms of debris, but unusual objects such as boat docks, bowling balls, canoes, hot tubs, and small wooden and steel sheds and buildings also sometimes become lodged against the dam.

[130] PPL Montana works with local and state government and law enforcement, other companies, and the news media to plan for various contingencies and improve how it might respond in a disaster or emergency.

[115] In 2011, the former smelter next to Black Eagle Dam was listed by the United States Environmental Protection Agency (EPA) as a Superfund hazardous and toxic waste site.

[149] Toxins present in the water and riverbed, according to the EPA, include antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, silver, sodium, and zinc.

[123][161] In mid-July, the River's Edge Trail Luminaria Walk occurs around Black Eagle Dam and the falls, and are illuminated with colored spotlights during the event.

For decades, two gravel spaces existed on River Drive North near the Bob Speck Municipal Golf Course where drivers could stop, get out, and view Black Eagle Falls and the dam.

[165] Construction also began on a 0.5-mile-long (0.80 km) section of trail designed to link Art Higgins Memorial Park (on the north bank of the Missouri River just behind the dam) with the island.

[166][167] There is no fee to enter Black Eagle Memorial Island, which is open daily to the public from 9 A.M. to 8 P.M. and is maintained by the Montana Department of Fish, Wildlife and Parks.

[171] The master plan, which covered both banks of the Missouri River from White Bear Island to Black Eagle Dam, inventoried the entire shoreline and assessed the riverbanks for condition, rehabilitation and refurbishment, and improvement opportunities.