FLOOD02208

• Designation Number: 547
• County: Gilpin
• Community: Black Hawk
• Basin: South Platte
• Title: Draft Report - Reconstituition of 1979 Flood Peaks, North Clear Creek, Gregory Gulch, and Chase Gulch
• Date: 4/26/2001
• Designation Date: 5/1/2001
• Floodplain - Doc Type: Floodplain Report/Masterplan

p~ & Associates, Inc.

April 20, 2001

water resource consultants

841 Front Street
Louisville, Colorado 80027-1849
Phone [phone] FAX [phone]
E-moJl: [e-mail]

Mr. Mark Matulik, r.E.
Colorado Water Conservation Board
1313 Sherman Street, Room 721
Denver, Colorado 80203

REF: 0107 A: North Clear Creek, Gregory Gulch, and Chase Gulch Flood Peaks

Dear Mark:

Enclosed, please find a copy of the draft report Reconstitution of 1979 Flood Peaks,
North Clear Creek, Gregory Gulch, and Chase Gulch, for your review and use. We were
able to calibrate the TR20 model to the 1979 flood peaks using slight and reasonable
adjustments in Curve Numbers. We found we had to use a "Type IA" 24-hour storm
distribution for North Clear Creek and a 24-hour "Type II" storm distribution for Gregory
and Chase Gulch to produce reasonable calibration results, We also analyzed the impact
of Dorothy Lee and Chase Gulch Water Supply Reservoirs on flood peaks.

We have enclosed a CD with the data from the TR20 runs to the report. Please ignore the
folders entitled "with reservoir" and "no reservoir"; only use the files in the TR20 folder.

Once we have received your comments and incorporated any changes you desire, we will
provide you with a final copy of the report for your use and distribution. Please contact
us if you have any questions. Thank you.

Sincerely,

LOVE & ASSOCIATES, me.

L,~

By

Roger J. Peterson, P .E.

Attachment: Report, CD
cc: Larry Lang, P.E.