Colstrip is a city in Rosebud County, Montana, United States. The population was 2,096 at the 2020 census.
Established in 1924 and incorporated as a city in 1998, Colstrip is the largest city in Rosebud County, with 25.2%
History
20th century
left|thumb|200px| Open pit strip mining with shovels at Colstrip's Rosebud Mine
Colstrip was established by the Northern Pacific Railway in 1924 as a company town to provide coal for their steam locomotives. The mining at Rosebud Mine, two miles south of the town, is open pit strip mining, where draglines remove soil above the layer of bituminous coal from the Fort Union Formation.
During The Second World War, the Colstrip mine was identified as strategically important because it supplied coal for the Northern Pacific Railway steam locomotives hauling military equipment for the war effort. The mine was guarded from sabotage, and the employees were not allowed to quit their jobs.
In 1958, the railroad switched to using diesel locomotives and the Colstrip mine was shut down.
In 1959, Montana Power Company purchased the rights to the mine and the town. It resumed mining operations in the 1970s, with plans to build coal-fired electrical plants. The Rosebud Mine opened in 1968.
The power plants were built in the 1970s and 1980s by a collection of contractors including Bechtel. During this construction period, Colstrip was a boomtown, with a large increase in population. Plants 1 and 2 became operational in 1975 and 1976, and plants 3 and 4 became operational in 1984 and 1986.
In 1974, construction of Colstrip's Castle Rock Lake (formerly called a surge pond) was completed.
The Colstrip plants produce electricity from coal using steam. The water for the steam is pumped in an underground pipe from the Yellowstone River and stored in the lake. The lake is stocked with fish and is the home for a wide variety of wildlife.
In 1990, the Colstrip Energy Limited Project began commercial operations. Located six miles (10 km) north of Colstrip, this experimental electricity production facility is owned by Rosebud Energy Corp., a partnership that at one point included Enron. The plant uses high sulfur waste coal from the Rosebud Coal Mine's topmost one foot layer of coal.
In 1998, plants 1-4 were sold to a group led by PPL Corporation (PPL) and Puget Sound Energy (PSE). The Rosebud Coal Mine was sold to Westmoreland Mining LLC. In this same year, the City of Colstrip was incorporated.
21st century
In June 2015, PPL spun off its power generation assets, including the Colstrip plants, to become Talen Energy.
In 2016, PSE reached an agreement with the Sierra Club and the Montana Environmental Information Center to shut down units 1 and 2 of the coal-fired generating plant by the year 2022. The agreement said nothing about Units 3 and 4 However, the existing electrical transmission capacity that transmits power from Colstrip to the Pacific Northwest may be used to transmit wind energy. Another blow to Colstrip's economy came in 2016, when an application to create a junction point from BNSF Railway to connect to Tongue River Railroad was denied.
In June 2019, Talen Energy announced the closure of two of the four coal burning units by the end of the year. At the time, the power plant was the sixth-largest source of greenhouse emissions in the U.S. Units 3 and 4 remained in operation.
In January 2020, PSE announced that Unit 1 and Unit 2 had ceased operating in early January". Units 3 and 4 were to remain operational but would be closed within the next five years.
In January 2023, Avista made a deal giving NorthWestern Energy their 15% share of the plant for free. The deal was to take effect in 2025. A Washington state law bans use of coal-generated electricity, forcing Avista to relinquish their stake in the company.
In March 2025, the plant owner, backed by Montana politicians, asked for a two-year extension using the second Trump administration's offer to grant presidential pollution waivers. The plant owners argued that continued operation would control energy costs and guarantee grid reliability.
Geography
thumb|left|The Rosebud mine in 2006, taken from the [[International Space Station]]
The Powder River Basin contains the 25,000-acre Rosebud Mine, a strip mine a few miles south of Colstrip, and the Northern Cheyenne Indian Reservation. Bituminous coal lies in the Fort Union Formation.
According to the United States Census Bureau, the city has a total area of , all land.
There are 30 city parks and 300 acres of green space owned by the city.
South of town , is Deer Medicine Rocks, a National Historic Landmark. These sandstone cliffs are covered with petroglyphs and pictographs. Hills covered in sandstone formations are typical of this area. The topography in the county is mostly rolling with small hills. Deer and pronghorn are plentiful.
Economy
As of 2017, the majority of jobs in the city were in local and federal governments, employing 1,732 people.
Environmental remediation of the 2 closed energy units, particularly groundwater contamination from seepage and leakage of the effluent ponds, is costly. In 2017, it was calculated as ranging from $85 million to $143 million.