BOARD00961

• Board Meeting Date: 9/22/2003
• Description: Flood Section - Probable Maximum Precipitation Site-Specific Study for the Cherry Creek Reservoir-Study Findings and Recommendations
• Board Meetings - Doc Type: Memo

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1999

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SENATE JOINT RESOLUTION 99-023

BY SENATORS Andrews, Evans, Lamborn, Arnold, Blickensderfer, Congrove, Hillman,
Musgrave, and Tebedo;

also REPRESENTATIVES Clapp, Nufiez, Spence, Allen, Dean, Decker, Fairbank, Hefley,
Hoppe, Lee, Miller, Scott, Smith, and Spradley.

CONCERNING AN INDEPENDENT PEER REVIEW OF THE FEDERAL NATIONAL
WEATHER SERVICE PROBABLE MAXIMUM PRECIPITATION STUDY USED BY
THE UNITED STATES ARMY CORPS OF ENGINEERS IN THEIR REDESIGN STUDY
RELATING TO THE CHERRY CREEK DAM.

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WHEREAS, The terms "probable maximum flood" and "probable maximum precipitation"
as used by the United States Army Corps of Engineers are misleading terminology because
they are both improbable events with respect to the Cherry Creek Basin; and

WHEREAS, The United States Army Corps of Engineers has assumed the Cherry Creek
Dam will fail following an extraordinarily improbable chain of events; and

WHEREAS, The probable maximum precipitation is a theoretical maximum only and has
somewhere between a one in one million to a one in one billion chance of occurring in any
single year; and

WHEREAS, The site specific probable maximum precipitation study completed for the
United States Army Corps of Engineers by the National Weather Service has erroneously
applied meteorological procedures and fails to include documented historical paleo flood
evidence; and

WHEREAS, This error is further compounded by the erroneous assumption that the
topographic effects of the Palmer Divide will increase the rainfall in the Cherry Creek
. Basin; and

WHEREAS, The probable maximum flood used by the United States Army Corps of

h ://www.state.co.us/govdir/legdir/sess1999/sres99/sjr023.htm

9/1 0/2003