27e

• Board Meeting Date: 11/19/2008
• Description: CF Section – En-bloc Non-Reimbursable Investments - NOAA Atlas 2 Precipitation Atlas Update
• Board Meetings - Doc Type: Memo

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
TO: Colorado Water Conservation Board Members
Bill Ritter, Jr.
Governor
FROM: Kevin Houck, P.E., Engineer
Harris D. Sherman
Watershed Protection & Flood Mitigation Section
DNR Executive Director
Jennifer L. Gimbel
DATE: November 7, 2008
CWCB Director
Dan McAuliffe
Agenda Item 27e, November 18-19, 2008 Board Meeting
SUBJECT:
CWCB Deputy Director
Watershed Protection and Fl ood Mitigation Section –
En-bloc Non-Reimbursable Investments
NOAA Atlas 2 Precipitation Atlas Update
Background
Floodplain delineations and design of hydraulic stru ctures must use design point rainfall as a
basic data input. Currently, the tool most commonly used is the Precipitation Atlas prepared in
1973 by the National Oceanic and Atmospheric Admi nistration (NOAA), generally referred to as
the NOAA Atlas 2. The NOAA Atlas 2 uses isohyetal figures to por tray design rainfall depths
for the entire State of Colorado for return fre quencies ranging from 2-year to 100-year and for
durations of 5 minutes to 24 hours. While this A tlas is very useful in obtaining the data needed
for hydraulic designs and floodplain an alyses, at 35 years old, it is re garded as being out of date.
Discussion
This request is to provide funds for the pur pose of updating the long out-of-date NOAA Atlas 2
for the State of Colorado. NOAA is currently performing work around the country in groups of
states with the goal of updati ng design precipitation data thro ughout the nation. By grouping the
states together in group s of projects, NOAA is able to a ttain benefits of scale and bring
additional partners into the pr ojects. NOAA issued a proposal with Colorado grouped with six
Midwestern states that have funding available but th is project will not be able to move forward at
this time if Colorado can commit the funds.
Staff Request
The CWCB Staff requests that the Board cons ider funding a one-time request of $300,000 for the
purpose of partnering with NOAA and other states to update the Atlas to current standards.
Recommendation
Staff recommends that the Board request the Ge neral Assembly to aut horize up to $300,000 from
the Construction Fund to be appropriated to the Colorado Water Conservation Board for the
purpose of updating the Atlas to curren t statistical stan dards and accuracy.
Water Supply Protection • Watershed Protection and Flood Mitigatio n • Stream & Lake Protection • Water Supply Planning & Financ e
Water Conservation & Drought Planning • In trastate Water Management & Development