This is a list of dams in the United States that have been removed as physical impediments to free-flowing rivers or streams. Dams are not included if they have instead failed, or if they have been decommissioned but not yet removed. Dam removal takes many forms, and some removals may leave structures behind or alter the natural course of a river.
According to the non-profit advocacy organization American Rivers, 2,119 dams were removed in the United States between 1912 and 2023. The peak year was 2018, which saw 109 removals. Pennsylvania removed 390 dams in this period, more than any other state. Mississippi is the only state with no documented dam removals. [1]
The 46-foot (14 m) [2] Brown Bridge Dam [ broken anchor ], 56-foot (17 m) [3] Boardman Dam [ broken anchor ], and 34-foot (10 m) [4] Sabin Dam [ broken anchor ] were removed from the Boardman River in Michigan as part of the Boardman River Dams Ecosystem Restoration Project after their hydropower was decommissioned in 2005.
The 100 ft (30 m) privately owned Rindge Dam on Malibu Creek in the Santa Monica Mountains of California was built in 1924 and has been allowed to completely fill with sediment, making it functionally obsolete but still a potential hazard. Malibu Creek once supported the southernmost steelhead population in the world. But today, steelhead no longer occupy the creek.
The similar 1947 Matilija Dam near Ojai, California was built against the advice of the U.S. Army Corps of Engineers, among others, and also blocked steelhead trout spawning grounds. After being notched twice and largely silted up, 90% of its design capacity has been lost. As of 2013 stakeholders agree that the dam and its sediment be removed, but no funding source has been identified. [5]
Built in 1916, the 25-foot (7.6 m) [6] Fossil Creek Dam supported hydroelectric power production on Fossil Creek, a tributary of the Salt River via the Verde River. The dam was removed in 2008 to restore flow, travertine deposition, and native fish populations. [7]
The 710 ft (220 m) Glen Canyon Dam has been proposed for removal because of the negative effects it has on the water quality and riparian habitat of the Colorado River in Grand Canyon National Park. In addition, the reservoir impounded behind it, Lake Powell has filled all of the canyons for up to 160 miles (260 km) above the dam. This lake, while providing recreational opportunities, has eliminated more than 160 miles (260 km) of habitat for endangered Colorado River fish species.
The reservoir also loses more than 6 percent of the total annual flow of the Colorado River to evaporation and seepage. [8] Advocates of dam removal such as the Glen Canyon Institute also cite these losses of stored water as reason to decommission the dam. If it were to be removed, it would dwarf any completed dam removal project in history.
On the South Fork Clearwater River, the Grangeville Dam was a 56-foot-tall (17 m), 440-foot-long (130 m) arched concrete hydroelectric dam constructed by the Washington Water Power Company in 1911. A wooden fish ladder had been installed but it collapsed in 1949. The dam was removed in the interest of fish passage and since the hydropower facilities had become obsolete. The dam was destroyed by dynamite at 6:35 PM on August 19, 1963, following two prior detonations that day which had failed to collapse the structure. [9] At the time, the dam was the largest ever to be removed, a record which stood for decades. [10]
In 1971 the 39 ft (12 m) tall Lewiston Dam was removed from the main stem of the Clearwater River just above its confluence with the Snake River. Built in 1927 as a hydroelectric facility, the dam lacked fish ladders and was rendered obsolete by the downstream Lower Granite Dam.
On the White Salmon River, the 123 ft (37 m) Condit Dam blocked access for Pacific Salmon and steelhead runs on 33 miles (53 km) of river. PacifiCorp proposed to remove the dam, rather than paying for fish passage upgrades. Removal was proposed in 2006, but actions from Skamania and Klickitat counties held up the process. In fall 2008, salmon were trucked up above to dam to allow them to spawn higher up the river. In October 2011, PacifiCorp contractors used explosives to blow a 15-foot (4.6 m) hole in the dam to drain its reservoir and allow young salmon to enter the Columbia River and head to sea.
The 21-foot (6.4 m) Milltown Dam lay the junction of the Clark Fork River and Blackfoot River in Montana. The dam held very high levels of toxic sediments from 100 years of mining and logging. Its 2008 removal improved water quality, trout habitat, and the general ecological condition of the watershed. [11]
On the Sandy River in Oregon, the 50-foot (15 m) tall Marmot Dam was removed by Portland General Electric in 2007. Its removal has been extremely successful at improving access for Pacific Salmon and steelhead to the upper Sandy River watershed up into the Mount Hood Wilderness.
Four dams along the lower Snake River, built and still operated by the United States Army Corps of Engineers, serve as hydroelectric power sources as well as maintaining an inland port at Lewiston, Idaho for agricultural barge traffic. The four are candidates for removal because of millions of cubic yards accumulated behind the dams, which are raising water levels for riverside cities. They include: the 1975 100 ft (30 m) Lower Granite Dam, the 1970 98 ft (30 m) Little Goose Dam, the 1969 100 ft (30 m) Lower Monumental Dam, and the 1962 100 ft (30 m) Ice Harbor Dam.
Three million new cubic yards of sediment are deposited behind the lower four dams on the Snake River annually. [12] The city of Lewiston, Idaho and others along the Snake have built a system of levees maintained by the Army Corps of Engineers. The levees in Lewiston were designed to leave five feet between water levels and the top of the levees. As of 2011, two feet remained. As water levels continue to rise, either some of the dams must be removed or dredged, or the municipal levees will continue to be raised. The Corps admits that the amount of sediment in the riverbed is too great for dredging to be effective, and Lewiston community leaders are worried that higher levees will further cut the town off from its rivers. [13] The Corps began dredging behind Lower Granite Dam in 2015. [14]
The 6-foot (1.8 m) tall Cuddebackville Dam on the Neversink River was built in two portions dating from the 1820s (for water diversion into a canal) and 1915 (for hydroelectric power). The dam had been abandoned since 1945, and was removed in October 2004 by the U.S. Army Corps of Engineers in a novel partnership with the Nature Conservancy. The removal benefited aquatic life in the area, specifically the Dwarf Wedge Mussel and the American Shad.
The Elwha Ecosystem Restoration project on the Olympic Peninsula of Washington started in 2012, and finished in 2014, the 108-foot (33 m) Elwha Dam and the 210-foot (64 m) Glines Canyon Dam were removed to restore stocks of Pacific Salmon and trout species to the Elwha River watershed. The removal of these blockades allows migratory salmon to travel past the dam sites and upriver, an event that has not occurred since the dams' creation in 1913. After spawning there, the salmon die and their carcasses decompose, releasing marine nutrients laid down in their bodies as they fed in the open ocean. This reintroduction provides a valuable research opportunity for interested parties. [15] Since the dam removal, reservoir beds that looked like moonscapes have returned to vibrant rich habitat. Within a year of the Elwha Dam removal, an increase in salmon-derived nutrients was documented in the American dipper. [16]
Built in 1837, the 24-foot (7.3 m) tall Edwards Dam on the Kennebec River in Maine blocked passage to Atlantic Salmon and American Shad. Its 1999 removal was the result of a landmark case in which a U.S. federal agency, the Federal Energy Regulatory Commission, required the decommissioning and removal of a dam against the operator's wishes.
After more than 20 years of advocacy from the Un-Dam the Klamath movement, the largest dam removal in history started, [17] the first of four dams – the Copco Number 2 Dam – was removed in fall 2023, [18] and the removal project was completed in August 2024. [19]
Two dams have been removed as part of the Penobscot River Restoration Project: the Great Works Dam in 2012 and the Veazie Dam in 2013, each 20 feet (6.1 m) tall. [20]
In 2008, the 80-foot (24 m) tall Elk Creek Dam was removed from the Elk Creek tributary to the Rogue River.
O'Shaughnessy Dam in California was completed in 1923 and represented the first great environmental controversy in the US as it was constructed in a national park. [21] The debate over the dam and reservoir continues today. Preservationist groups such as the Sierra Club lobby for the restoration of the valley, while others argue that leaving the dam in place would be the better economic and environmental decision. [22]
The two remaining dams on the Kinnickinnic River in River Falls, Wisconsin are being considered for removal in order to completely restore the Kinnickinnic River to its natural state. [24] The Kinnickinnic River, called the Kinni for short, is a 22-mile-long (35 km) [25] river in northwestern Wisconsin in the United States. The Kinni is a cold water fishery supporting a population of native Brook Trout and naturally reproducing Brown Trout. The Kinnickinnic River is officially designated as a Class I trout stream by the WI DNR, indicating it is a "high quality" trout water that has sufficient natural reproduction to sustain populations of wild trout, at or near carrying capacity. [26] The Kinnickinnic is also designated as an Outstanding Resource Water (ORW) by the WI DNR both above State HWY 35, and below the Powell Falls Dam, however, the stretch of the Kinni through the City of River Falls is not included in this designation where the river is impounded into two reservoirs which do not support a fishery. This ORW designation indicates the Kinni provides outstanding recreational opportunities, supports valuable fisheries and wildlife habitat, has good water quality, and is not significantly impacted by human activities. [27] This designation indicates that the State of Wisconsin has determined the Kinnickinnic River warrants additional protection from the effects of pollution. These designations are intended to meet federal Clean Water Act obligations requiring Wisconsin to adopt an “antidegradation” policy that is designed to prevent any lowering of water quality – especially in those waters having significant ecological or cultural value. [27]
Local stakeholder organizations in the FERC relicensing process include the Friends of the Kinni, the Kiap-TU-Wish Chapter of Trout Unlimited, the Kinnickinnic River Land Trust, and the River Alliance of Wisconsin. Government agencies also serving as stakeholder organizations include the Wisconsin DNR, the US Fish and Wildlife Service, and the National Park Service.
This list includes all known removals of dams greater than or equal to 65 feet (20 m) in height.
Dam | Height | Expected year | Location | Watercourse | Watershed |
---|---|---|---|---|---|
Matilija Dam | 198 ft (60 m) | Ojai, CA 34°29′N119°19′W / 34.49°N 119.31°W | Matilija Creek | Ventura River | |
Rindge Dam | 100 ft (30 m) | 2025–2035 | Malibu Creek State Park, CA 34°03′53″N118°41′56″W / 34.0646°N 118.699°W | Malibu Creek | Santa Monica Bay |
Dam | Height | Location | Watercourse | Watershed |
---|---|---|---|---|
Glen Canyon Dam | 710 ft (220 m) | Coconino County, AZ 36°56′15″N111°29′04″W / 36.9375°N 111.4844°W | Colorado River | Colorado River |
O'Shaughnessy Dam | 430 ft (130 m) | Yosemite National Park, CA 37°56′51″N119°47′18″W / 37.9475°N 119.7883°W | Tuolumne River | San Joaquin River |
Ice Harbor Dam | 213 ft (65 m) | Franklin County and Walla Walla County, WA 46°14′59″N118°52′48″W / 46.2496°N 118.88°W | Snake River | Columbia River |
Lower Monumental Dam | 152 ft (46 m) | Franklin County and Walla Walla County, WA 46°33′45″N118°32′13″W / 46.5624°N 118.537°W | ||
Little Goose Dam | 253 ft (77 m) | Columbia County and Whitman County, WA 46°35′15″N118°01′34″W / 46.5875°N 118.0261°W | ||
Lower Granite Dam | 181 ft (55 m) | Garfield County and Whitman County, WA 46°39′38″N117°25′42″W / 46.6605°N 117.4283°W |
Dam | Dam height | Watercourse | Removal completed | Notes |
---|---|---|---|---|
Pinery Feeder Dam | Cuyahoga River | 2020 | [28] | |
Brecksville Dam | 8 ft (2.4 m) |
Dam | Dam height | Watercourse | Removal completed | Notes |
---|---|---|---|---|
Marie Dorian Dam | 8 ft (2.4 m) | Walla Walla River | 1997 | The dam blocked passage to Pacific Salmon and steelhead into the Blue Mountains from the Columbia Basin. |
Dam | Watercourse | Removal completed | Notes |
---|---|---|---|
Island Woolen Mill Dam | Baraboo River | 1972 | Opened 120 miles (190 km) of a Wisconsin River tributary to fish and wildlife. [29] |
Reedsburg Woolen Mills Dam | 1973 | ||
Wonewoc Dam | 1996 | ||
Waterworks Dam | 1998 | ||
Oak Street Dam | 2000 | ||
LaValle Dam | 2001 | ||
Linen Mill Dam | 2001 |
Dam | River | Removal timeframe | Notes |
---|---|---|---|
Junction Falls Dam | Kinnickinnic River | 2023–2040 | In 2018, River Falls, Wisconsin, approved the removal of two little-used dams in the city. This would return the Kinnickinnic River to a free-flowing state and restore the city's namesake falls. [30] |
Powell Dam | 2025–2040 |
The Elwha River is a 45-mile (72 km) river on the Olympic Peninsula in the U.S. state of Washington. From its source at Elwha snowfinger in the Olympic Mountains, it flows generally north to the Strait of Juan de Fuca. Most of the river's course is within the Olympic National Park.
Rindge Dam is a 100-foot-tall (30 m) dam on Malibu Creek in the Santa Monica Mountains of Southern California. Located in Malibu Creek State Park, it sits just northeast of Malibu Canyon Road, and is partially visible from the turnouts south of the tunnel. The dam, a major obstacle to river wildlife, is due to be removed with demolition work beginning in 2025 and finishing in 2035.
The Sisquoc River is a westward flowing river in northeastern Santa Barbara County, California. It is a tributary of the Santa Maria River, which is formed when the Sisquoc River meets the Cuyama River at the Santa Barbara County and San Luis Obispo County border just north of Garey. The river is 57.4 miles (92.4 km) long and originates on the north slopes of Big Pine Mountain, at approximately 6,320 feet (1,930 m). Big Pine Mountain is part of the San Rafael Mountains, which are part of the Transverse Ranges.
Alameda Creek is a large perennial stream in the San Francisco Bay Area. The creek runs for 45 miles (72 km) from a lake northeast of Packard Ridge to the eastern shore of San Francisco Bay by way of Niles Canyon and a flood control channel. Along its course, Alameda Creek provides wildlife habitat, water supply, a conduit for flood waters, opportunities for recreation, and a host of aesthetic and environmental values. The creek and three major reservoirs in the watershed are used as water supply by the San Francisco Public Utilities Commission, Alameda County Water District and Zone 7 Water Agency. Within the watershed can be found some of the highest peaks and tallest waterfall in the East Bay, over a dozen regional parks, and notable natural landmarks such as the cascades at Little Yosemite and the wildflower-strewn grasslands and oak savannahs of the Sunol Regional Wilderness.
Condit Hydroelectric Project was a development on the White Salmon River in the U.S. state of Washington. It was completed in 1913 to provide electrical power for local industry, and is listed in the National Register of Historic Places as an engineering and architecture landmark.
The Elwha Dam was a 108-ft high dam located in the United States, in the state of Washington, on the Elwha River approximately 4.9 miles (7.9 km) upstream from the mouth of the river on the Strait of Juan de Fuca.
San Francisquito Creek is a creek that flows into southwest San Francisco Bay in California, United States. Historically it was called the Arroyo de San Francisco by Juan Bautista de Anza in 1776. San Francisquito Creek courses through the towns of Portola Valley and Woodside, as well as the cities of Menlo Park, Palo Alto, and East Palo Alto. The creek and its Los Trancos Creek tributary define the boundary between San Mateo and Santa Clara counties.
The Kinnickinnic River, called the Kinni for short, is a 22-mile-long (35 km) river in northwestern Wisconsin in the United States. The Kinni is a cold water fishery supporting a population of native Brook Trout and naturally reproducing Brown Trout.
Pescadero Creek is a major stream in Santa Cruz and San Mateo counties in California, United States. At 26.6 miles (42.8 km), it is the longest stream in San Mateo County and flows all year from springs in the Santa Cruz Mountains. Its source is at 1,880 feet (570 m) above sea level on the western edge of Castle Rock State Park, with additional headwaters in Portola Redwoods State Park, and its course traverses Pescadero Creek County Park and San Mateo County Memorial Park before entering Pescadero Marsh Natural Preserve at Pescadero State Beach and thence to the Pacific Ocean 14.4 miles (23 km) south of Half Moon Bay.
Glines Canyon Dam, also known as Upper Elwha Dam, was a 210-foot (64 m) tall concrete arch dam that impounded Lake Mills reservoir on the Elwha River in Clallam County, Washington. As of 2015, it is the tallest dam ever to be intentionally breached.
Lake Mills was a reservoir in Olympic National Park, Washington, United States, that existed from 1927 to 2012. It was formed by the Glines Canyon Dam on the Elwha River and was located about 13 miles from the mouth of the river on the Olympic Peninsula.
Lake Aldwell was a reservoir located about 4.9 miles (7.9 km) from the mouth of the Elwha River on the Olympic Peninsula in the U.S. state of Washington. The reservoir was created in 1913 behind the Elwha Dam, which was fully removed in 2012. The Elwha Dam blocked at least 70 miles (110 km) of fish habitat for Pacific Salmon and steelhead within Olympic National Park.
Matilija Creek is a major stream in Ventura County in the U.S. state of California. It joins with North Fork Matilija Creek to form the Ventura River. Many tributaries feed the mostly free flowing, 17.3-mile (27.8 km) creek, which is largely contained in the Matilija Wilderness. Matilija was one of the Chumash rancherias under the jurisdiction of Mission San Buenaventura. The meaning of the Chumash name is unknown.
Dam removal is the process of demolishing a dam, returning water flow to the river. Arguments for dam removal consider whether their negative effects outweigh their benefits. The benefits of dams include hydropower production, flood control, irrigation, and navigation. Negative effects of dams include environmental degradation, such as reduced primary productivity, loss of biodiversity, and declines in native species; some negative effects worsen as dams age, like structural weakness, reduced safety, sediment accumulation, and high maintenance expense. The rate of dam removals in the United States has increased over time, in part driven by dam age. As of 1996, 5,000 large dams around the world were more than 50 years old. In 2020, 85% percent of dams in the United States are more than 50 years old. In the United States roughly 900 dams were removed between 1990 and 2015, and by 2015, the rate was 50 to 60 per year. France and Canada have also completed significant removal projects. Japan's first removal, of the Arase Dam on the Kuma River, began in 2012 and was completed in 2017. A number of major dam removal projects have been motivated by environmental goals, particularly restoration of river habitat, native fish, and unique geomorphological features. For example, fish restoration motivated the Elwha Ecosystem Restoration and the dam removal on the river Allier, while recovery of both native fish and of travertine deposition motivated the restoration of Fossil Creek.
The Elwha Ecosystem Restoration Project is a 21st-century project of the U.S. National Park Service to remove two dams on the Elwha River on the Olympic Peninsula in Washington state, and restore the river to a natural state. It is the largest dam removal project in history and the second largest ecosystem restoration project in the history of the National Park Service, after the Restoration of the Everglades. The controversial project, costing about $351.4 million, has been contested and periodically blocked for decades. It has been supported by a major collaboration among the Lower Elwha Klallam Tribe, and federal and state agencies.
Marsh Creek is a stream in east Contra Costa County, California in Northern California which rises on the eastern side of Mount Diablo and flows 30 miles (48 km) to the Sacramento–San Joaquin River Delta at Oakley, California, near Big Break Regional Shoreline. The creek flows through Marsh Creek State Park (California), where water is impounded to form Marsh Creek Reservoir, then through the city of Brentwood, California.
Searsville Dam is a masonry dam in San Mateo County, California, that was completed in 1892, one year after the founding of Stanford University, and impounds Corte Madera Creek to form a reservoir known as Searsville Reservoir or Searsville Lake. Searsville Dam is located in the Jasper Ridge Biological Preserve and is owned and operated by Stanford University. Neighboring cities include Woodside and Portola Valley, California.
Iron Gate Dam was an earthfill hydroelectric dam on the Klamath River in northern California, outside Hornbrook, California, that opened in 1964. The dam blocked the Klamath River to create the Iron Gate Lake Reservoir. It was the lowermost of a series of power dams on the river, the Klamath River Hydroelectric Project, operated by PacifiCorp. It also posed the first barrier to migrating salmon in the Klamath. The Iron Gate Fish Hatchery was placed just after the dam, hatching salmon and steelhead that were released back into the river.
Guadalupe Creek is a 10.5 miles (16.9 km) northward-flowing stream originating just east of the peak of Mount Umunhum in Santa Clara County, California, United States. It courses along the northwestern border of Almaden Quicksilver County Park in the Cañada de los Capitancillos before joining Los Alamitos Creek after the latter exits Lake Almaden. This confluence forms the Guadalupe River mainstem, which in turn flows through San Jose and empties into south San Francisco Bay at Alviso Slough.
Matilija Dam is a concrete arch dam in Ventura County, California, completed in 1947. Designed for water storage and flood control, it impounds Matilija Creek to create the Matilija Reservoir in the Los Padres National Forest, south of the Matilija Wilderness and north of Ojai.