Lawn Lake Dam

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Coordinates: 40°27′51″N105°37′41″W / 40.464065°N 105.628077°W / 40.464065; -105.628077

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The flood caused by the failure of Lawn Lake Dam scoured Roaring River valley and deposited an alluvial fan of debris in Horseshoe Park. Roaring River - Alluvial Fan.jpg
The flood caused by the failure of Lawn Lake Dam scoured Roaring River valley and deposited an alluvial fan of debris in Horseshoe Park.

Lawn Lake Dam was an earthen dam in Rocky Mountain National Park, United States that failed on July 15, 1982, at about 6 a.m., in an event known as the flood of 1982. The sudden release of 30 million cubic feet (849,000 m3) of water resulted in a flash flood that killed three people camping in the park and caused $31 million in damage to the town of Estes Park, Colorado and other downstream areas.

Lawn Lake

Lawn Lake was originally a natural lake with a surface area of 16.4 acres (6.6 ha), located at an elevation of approximately 11,000 feet (3,400 m) in the Rocky Mountains. In 1903 a group of farmers from Loveland built a dam to increase it to a surface area of 48 acres (19.4 ha) for the purpose of providing water for irrigation in Loveland. [1]

Dam failure

Over the years the road that had been cut to permit construction of the dam fell into disrepair and ceased to exist. Because of the dam's remote and difficult location, inspection and repairs lapsed. The Colorado State Engineer determined that the probable cause of the dam failure was deterioration of lead caulking on the joint between the outlet pipe and the gate valve leading to internal erosion of the earth-fill dam. [2] There had been issues reported during inspections in 1951, 1975, 1977 and 1978. [3]

The mouth of Lawn Lake (the site of the dam) in July 2007, 25 years after the accident. LawnLakeMouth.jpg
The mouth of Lawn Lake (the site of the dam) in July 2007, 25 years after the accident.
Lawn Lake in 2007, 25 years after the accident, with the shore still showing the former extent of the lake. LawnLake.jpg
Lawn Lake in 2007, 25 years after the accident, with the shore still showing the former extent of the lake.

When the dam failed the waters rushed down the Roaring River valley, which falls 2,500 feet (760 m) in 6 miles (9.7 km), at a peak rate of 18,000 cubic feet per second (510 m3/s), scouring a large gully out of the mountain stream and killing one person camping alongside it. At this rate, the lake emptied in about half an hour. When the waters reached the broader valley of Fall River at Horseshoe Park they spread out and slowed, leaving behind a large alluvial fan of debris. The flood continued down Fall River and hit the Cascade Dam which stored water to run a hydroelectric plant about a mile (2 km) downstream. Cascade Dam failed from the onslaught and added its waters to the flood. The Aspenglen campground was destroyed and two campers who returned to recover camping gear lost their lives, due to insufficient warning from park rangers. [4]

The flood entered the town of Estes Park and caused severe damage to 177 downtown businesses (75 percent of Estes Park's commercial activity). [5] In Estes Park the flood joined the Big Thompson River and flowed into Lake Estes on the eastern edge of the city. Olympus Dam, part of the Colorado-Big Thompson Project, there withstood the deluge and the flood was halted. [1]

Aftermath

The scar left by the scouring of Roaring River and the alluvial fan at Horseshoe Park are still very apparent 37 years later and will remain for a very long time. Twenty-five years after the accident, the extent of the former reservoir is still clearly evident, and at the mouth of the lake, the start of the Roaring River flows through the location of the former dam.

As a consequence of the dam failure, aging dams at Pear Reservoir, Bluebird Lake and Sandbeach Lake in the park were demolished and removed. [6]

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Roaring River (Colorado) River in Larimer County, Colorado, United States of America

The Roaring River is a 6.5-mile-long (10.5 km) tributary of the Fall River in Larimer County, Colorado. The river's source is Crystal Lake in the Mummy Range of Rocky Mountain National Park The river flows through Lawn Lake before a confluence with the Fall River in Horseshoe Park. The collapse of the Lawn Lake Dam in 1982 scoured the river's channel and deposited an alluvial fan of debris in Horseshoe Park.

Course of the Colorado River

The Colorado River is a major river of the western United States and northwest Mexico in North America. Its headwaters are in the Rocky Mountains where La Poudre Pass Lake is its source. Located in north central Colorado it flows southwest through the Colorado Plateau country of western Colorado, southeastern Utah and northwestern Arizona where it flows through the Grand Canyon. It turns south near Las Vegas, Nevada, forming the Arizona–Nevada border in Lake Mead and the Arizona–California border a few miles below Davis Dam between Laughlin, Nevada and Needles, California before entering Mexico in the Colorado Desert. Most of its waters are diverted into the Imperial Valley of Southern California. In Mexico its course forms the boundary between Sonora and Baja California before entering the Gulf of California. This article describes most of the major features along the river.

Roaring Brook (Lackawanna River tributary)

Roaring Brook is a tributary of the Lackawanna River in Lackawanna County, Pennsylvania, in the United States. It is approximately 21 miles (34 km) long and flows through Covington Township, Madison Township, Moscow, Roaring Brook Township, Elmhurst Township, Dunmore, and Scranton. The watershed of the stream has an area of 56.3 square miles (146 km2). Its named tributaries include Little Roaring Brook, Rock Bottom Creek, White Oak Run, Van Brunt Creek, Bear Brook, and East Branch Roaring Brook. It has a high level of water quality for much of its length. However, it is affected by abandoned mining land, stormwater, and other impacts in its lower reaches. Reservoirs in the watershed include the Hollister Reservoir, the Elmhurst Reservoir, and others. The stream also flows through the Nay Aug Gorge and passes over the Nay Aug Falls, which are on the National Register of Geologic Landmarks. It flows through a concrete channel in its lower reaches. The topography of the watershed contains rolling hills in its upper reaches and the mountainous land of the Moosic Mountains in its lower reaches.

History of Rocky Mountain National Park began when Paleo-Indians traveled along what is now Trail Ridge Road to hunt and forage for food. Ute and Arapaho people subsequently hunted and camped in the area. In 1820, the Long Expedition, led by Stephen H. Long for whom Longs Peak was named, approached the Rockies via the Platte River. Settlers began arriving in the mid-1800s, displacing the Native Americans who mostly left the area voluntarily by 1860, while others were removed to reservations by 1878.

Horseshoe Park

Horseshoe Park is a flat at 8,524 feet (2,598 m) in elevation in Larimer County, Colorado. It is within the Rocky Mountain National Park, which lies between Estes Park to the east and Grand Lake, Colorado on the west. Horseshoe Park is home to bighorn sheep, elk and other wildlife, and it is a wetland sanctuary for wide variety of birds. Recreational activities include picnicking, hiking, cross-country skiing and snowshoeing. Roaring River, Lawn Lake and Crystal Lake are located here.

References

  1. 1 2 "The Lawn Lake Flood". Town of Estes Park. Archived from the original on December 9, 2011.
  2. Katie Keller Lynn (September 2004), Sid Covington (ed.), Rocky Mountain National Park Geologic Resource Evaluation Report (PDF), National Park Service Geologic Resources Division, p. 6, retrieved 2010-07-24CS1 maint: discouraged parameter (link)
  3. "Case Study: Lawn Lake Dam (Colorado, 1982)". Association of State Dam Safety Officials. Retrieved 2019-04-13.CS1 maint: discouraged parameter (link)
  4. "Coates v. United States, 612 F. Supp. 592 (C.D. Ill. 1985)".
  5. Cordsen, John (13 July 2012). "1982 flood changed downtown Estes Park". Trail-Gazette. Retrieved 3 July 2018.CS1 maint: discouraged parameter (link)
  6. High Elevation Dam Removals in Rocky Mountain National Park Archived 2010-06-20 at the Wayback Machine