Ryan dam
Encyclopedia
Ryan Dam is a hydroelectric dam on the Missouri River
, ten miles (16 km) downstream from the city of Great Falls
in the U.S. state
of Montana
. The dam is 1336 feet (407.2 m) long and 61 feet (18.6 m) high; its reservoir
is 7 miles (11.3 km) long and has a storage capacity of 5000 acre.ft. It is a run-of-river
dam. The dam is built on the largest of the five Great Falls of the Missouri, and these specific falls are also called "Grand Falls". Since 1915, the six-unit powerhouse on the left side of the dam has occupied a significant portion of the 87 feet (26.5 m) high waterfall.
The dam, built just upstream of the falls and a small island named Ryan Island, is divided into two parts. On the right side of the dam is a concrete-arch spillway structure, that when functioning, releases water over the remains of the waterfall. The center part of the dam consists of a dike that extends from the falls' base to Ryan Island (separating the tailrace from the main river, which it meets a few hundred yards downstream). It also contains a concrete gravity structure facing towards the right bank of the river and tilted to face slightly downstream. This segment of the dam contains the outlet works
, a water jet that bursts out and cascades over the waterfall. The left side of the dam is a large powerhouse topped by a concrete gravity structure.
Since the dam's construction in the Missouri River gorge, it has flooded a fair portion of the Great Falls - the cascades between Grand Fall and Crooked Falls, which lies several miles upstream - and reduced the flow over Great Falls to such an extent that much of the bedrock is visible. The dam was constructed on top of a 10 feet (3 m) cascade that Lewis and Clark observed to lie just upstream of Grand Fall. Upstream of Ryan Dam the next dam is Rainbow Dam
, and the uppermost is Black Eagle Dam
.
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
, ten miles (16 km) downstream from the city of Great Falls
Great Falls, Montana
Great Falls is a city in and the county seat of Cascade County, Montana, United States. The population was 58,505 at the 2010 census. It is the principal city of the Great Falls, Montana Metropolitan Statistical Area, which encompasses all of Cascade County...
in the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. The dam is 1336 feet (407.2 m) long and 61 feet (18.6 m) high; its reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
is 7 miles (11.3 km) long and has a storage capacity of 5000 acre.ft. It is a run-of-river
Run-of-the-river hydroelectricity
Run-of-the-river hydroelectricity is a type of hydroelectric generation whereby a considerably smaller water storage called pondage or none is used to supply a power station. Run-of-the-river power plants are classified as with or without pondage...
dam. The dam is built on the largest of the five Great Falls of the Missouri, and these specific falls are also called "Grand Falls". Since 1915, the six-unit powerhouse on the left side of the dam has occupied a significant portion of the 87 feet (26.5 m) high waterfall.
The dam, built just upstream of the falls and a small island named Ryan Island, is divided into two parts. On the right side of the dam is a concrete-arch spillway structure, that when functioning, releases water over the remains of the waterfall. The center part of the dam consists of a dike that extends from the falls' base to Ryan Island (separating the tailrace from the main river, which it meets a few hundred yards downstream). It also contains a concrete gravity structure facing towards the right bank of the river and tilted to face slightly downstream. This segment of the dam contains the outlet works
Outlet works
A set of outlet works is a device used to release and regulate water flow from a dam. Such devices usually consist of one or more pipes or tunnels through the embankment of the dam, directing water usually under high pressure to the river downstream...
, a water jet that bursts out and cascades over the waterfall. The left side of the dam is a large powerhouse topped by a concrete gravity structure.
Since the dam's construction in the Missouri River gorge, it has flooded a fair portion of the Great Falls - the cascades between Grand Fall and Crooked Falls, which lies several miles upstream - and reduced the flow over Great Falls to such an extent that much of the bedrock is visible. The dam was constructed on top of a 10 feet (3 m) cascade that Lewis and Clark observed to lie just upstream of Grand Fall. Upstream of Ryan Dam the next dam is Rainbow Dam
Rainbow Dam
Rainbow Dam is a hydroelectric dam on the Missouri River, high and long, located six miles northeast of Great Falls in the U.S. state of Montana and just upstream of Rainbow Falls, a 45 ft waterfall that is the third of the five Great Falls of the Missouri. The dam, built in 1910, generates...
, and the uppermost is Black Eagle Dam
Black Eagle Dam
Black Eagle Dam is a hydroelectric gravity weir dam located on the Missouri River in the city of Great Falls, Montana. The first dam on the site, built and opened in 1890, was a timber-and-rock crib dam. This structure was the first hydroelectric dam built in Montana and the first built on the...
.