FLOOD06461

• County: Larimer
• Community: Estes Park
• Stream Name: Fall River, Lawn Lake
• Basin: South Platte
• Title: The Lawn Lake Dam Failure and the Fall River Flood
• Date: 8/6/1982
• Prepared For: FEMA
• Prepared By: Many
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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PART I
DESCRIPTION OF THE DISASTER

Shortly before 6 o'clock on the clear morning of Thursday,
July 15, 1982, a 79-year-old privately-owned earthen dam
at Lawn Lake, high in the Rocky Mountain National Park west
of Estes Park, Colorado failed, sending an estimated flow
rate of 8,000 cfs down the Roaring River into Horseshoe Park
and the Fall River drainage system. (ATTACHMENT 1) There,
the rise of water in the Fall River caused Cascade Lake dam
(holding 8-10 feet of water) to also fail sending an inter-
mediate surge down the channel. At the upper (west) end of
Elkhorn Avenue near the beginning of the downtown business
corridor, the flood waters could not pass under a bridge
clogged with debris and instead flowed over the structure and
also down Elkhorn Avenue through the central part of town.
(ATTACHMENT 2) The flooding washed away bridges, destroyed
road systems, inundated 177 businesses (75% of all the town's
commercial activity) and 108 residences. It also destroyed
a hydroelectric plant, fish hatchery, and caused two confirmed
deaths with two others still missing.

Due to the unique nature of this event, flooding was brief
(only a few hours) but of unprecedented severity. At Estes
Park, the estimated flow rate was 5,500 to 6,000 dfs. As a
comparison, figures for a 500-year flood on the Fall River
estimate a flow of only 830 cfs. Typical channel flood depths
during the peak discharge were 10 to 12 feet or about 2.5 times
the average SOD-year flood depth estimated in the Flood Insur-
ance Study. Most businesses in the downtown area reported
3 to 4 feet of water in their establishments.

The flood occurred during the time of the year that most of
the affected businesses depend upon to generate a major por-
tion of their gross yearly income. The Forward Estes Park
Foundation, a consortium of local businessmen, had estimated
that Estes Park receives 47 percent of its annual income be-
tween July 15 and September 1. Total dollar losses are esti-
mated by Federal and State recovery officials to be approxi-
mately $30.7 million. A breakdown of these damage estimates
follows:

Homes and Businesses
(including economic losses)

$19,000,000

Agricultural

2,550,000

Public (Federal, State and local)

4,130,000

Rocky Mountain National Park

5,000,000

$3.0,680,000

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