FLOOD00567

• County: Boulder
• Community: Lyons
• Title: Lyons Flood Hazard Mitigation Plan: The August 10, 1994 Flood
• Date: 9/1/1994
• Prepared For: Lyons
• Prepared By: Town of Lyons, Colorado Office of Emergency Management
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

LYONS COLORADO FLOOD HAZARD MIT/GA TION PLAN

irrigation which may prove to be a costly
endeavor due to the frequency of floods in
this area.

OTHERPOTENTlALFLOOD
HAZARDS

In addition to severe weather conditions,
other factors threaten the community.
Located above the town, lies Button Rock
Dam which retains Ralph Price Reservoir,
the City of Longmont's water supply. The
North St. Vrain creek, which is a spill-off
water-way for this reservoir, leads directly
towards the town.

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Button Rock Dam and Resuvoir enclosed in Button
Rock Presuve(elevation 6,400 ft.) with regards to
Lyons (elevation 5,000 ft.)

The dam stands 210ft. high and has a
capacity to hold 16,084 acre ft. of water.
This high-hazard, earthen dam has a crest
width of30 ft., base width of 1,030 ft. and
is 925 ft. in length. It is classified as a
class-I, high-hazard dam due to its
composition (rock and mud) and elevated
position with respect to Lyons and other
nearby towns. The dam, in conjunction
with the people and structures located

below, produce a high risk - high
vulnerability situation. If this dam failed
Lyons and other surrounding towns would
be devastated by flood waters.

Water storage tanks pose another danger.
On the comer of Fourth and Reese streets
are the town's two water tanks which sit on
an elevated landform. The tanks impose
increased flood risk to neighboring
properties making property owners more
susceptible to flood loss and damage.
Floods from water tanks can be just as
damaging and dangerous as riverine floods
or rainfall floods.

Overall, flood risk and vulnerability

Increase:

<:> as the amount and location of stored
water supplks increase;
<:> as populatWn and development increase;

<:> as water paths continue to be alUred;

<:> as people continue to live in and develop in
des' ated d lain areas.

.,

Lyon's water supply tanks located on the corner of
Fourth and Reese Street.

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