The Rocky Mountain National Park has a fan shaped deposit that was formed by the flowing of streams the flattened, slowed and spread at the exit to the canyon onto the flatter plain. Lawn Lake which is at an elevation of eleven thousand feet was originally just over sixteen acres until a twenty-foot earthen dam was built on it during 1902.
This increased the capacity for water in the lake to approximately 257 million gallons. The water was usually released from the dam into the Big Thompson and Fall River at Estes Park using the Roaring Fork River channel. The water in the lake was used to irrigate the land around it. The damn was neglected due to the remote area that it was in which is believed to have led to its eventual erosion.
The dam at the Lawn Lake broke on July 15, 1982 at 6:30am and released an estimated 228 million gallons of water. The channel of the river overflowed carrying boulders and trees with it as it went down the side of the mountain. The Aspenglen had to be evacuated when the dam broke. The dam at Cascade Lake which was concrete and seventeen feet high failed when the water hit it and released another four million gallons of water onto the mounting.
When the flooding from the Lawn Lake was done there was a scar five miles long where the flood had went down the mountain. This scar ends at Horseshoe Park with a large fan shaped deposit made up of broken trees, boulders and silt. This is what is known as the Alluvial Fan in the Rocky Mountain National Park. The debris that formed the Alluvial Fan created a shallow wetland and lake called Fan Lake when it created a damn in the Fall River.
The flooding that created the Alluvial Fan in Colorado's Rocky Mountain National Park did over thirty million dollars worth of damage both in and around the town of Estes Park, Colorado which is adjacent to the park. The fan formed when the waters from the lake slowed down and spread out where the Horseshoe Park is bordered by the Fall River and a large area of fanned out debris was left behind to form a fan shape in the landscape. This area is now a tourist attraction of the Rocky Mountain National Park in Colorado.
The Alluvial Fan left behind at the Horseshoe Park and the scars left on the land are still present. There is a trail known as the Alluvial Fan Trail that takes visitors to the Rocky Mountain National Park in Colorado to see the Alluvial Fan formation. Visitors to the Rocky Mountains and the surrounding area have a number of site seeing options making it an ideal place to visit. There are numerous trails in the Rocky Mountain National Park for visitors to explore and they should make it a point to explore the Alluvial Fan Trail and see the natural wonder that is the Alluvial Fan.