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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STATE OF COLORADO

Colorado Water Conservation Board

Department of Natural Resources
1313 Sherman Street, Room 721
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
www.cwcb.state.co.us

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Bill Owens
Governor

MEMORANDUM

TO:
FROM:

Colorado Water Conservation Board Members; ~.
Larry Lang, Chief, Flood Protection Program t-( - .
Joe Busto, Flood Protection Program ~
September 7, 2003
Agenda Item 8
Probable Maximum Precipitation Site-Specific Study for the Cherry
Creek Reservoir - Study Findings and Recommendations

Greg E. Walcher
Executive Director

Rod Kuharich
CWCB Director

DATE:
RE:

Dan McAuliffe
Deputy Director

Attachment:

Senate Joint Resolution 99-023
U.S. Army Corps of Engineers letter dated August 4, 2003

Presentation:

Dr. Ed Tomlinson, Applied Weather Associates, Inc.

Background
Why a CWCB Probable Maximum Precipitation (PMP) Technical Review of the Corp's
Cherry Creek Dam Safety Study?
Following a series of public meetings with local governments and the public, the U.S. Army Corps
of Engineers (Corps) and National Weather Service (NWS) in 1998 and 1999 produced much
controversy regarding their study findings and recommendations. The public meeting presenters
delivered the message that the Cherry Creek Dam wasn't safe and $250 million worth of
improvements were recommended at Cherry Creek Dam and Reservoir and basin. Similarly, the
Corps' Probable Maximum Flood (pMF) analysis indicated in the event of a dam failure 10,000
people would be dead and billions of dollars worth of damages would happen in Denver, Colorado.
In response to the basin controversy, the Colorado General Assembly enacted Senate Resolution 99-
023. The CWCB members conducted a field tour and inspection of Cherry Creek Basin on March
19, 1999. This tour determined the level of Board involvement in the peer review of the Corps' study
as directed by 99-023.

. Excerpts from the Senate Resolution 99-023 illustrate the events that led to CWCB involvement:
"WHEREAS, the U.S. Army Corps of Engineers has assumed the Cherry Creek Dam will fail
following an extraordinarily improbable chain of events, .. .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, any government agency proposal to spend from $50 to $250 million of taxpayer money
must be based on data and assumptions that are as accurate as possible..........

Colorado Water Conservation Board
Flood Protection. Water Supply Planning and Finance. Stream and Lake Protection
Water Supply Protection. Conservation and Drought Planning