BOARD00088 ‎(2)‎

• Board Meeting Date: 11/14/2006
• Description: WSP Section and ISF Section - Arkansas River ISF Appropriation
• Board Meetings - Doc Type: Hearings

STATE OF COLORADO

.

Bill Owens, Governor
DEPARTMENT OF NATURAl RESOURCES
DIVISION OF WilDLIFE

AN EQUAL OPPORTUNITY EMPLOYER

Bruce McCloskey, Dinlctor
6060 Broadway
Denver, Colorado 80216
Telephone: [phone]

May 5, 2006

Mr. Ted Kowalski
Colorado Water Conservation Board
Water Supply Protection Section
1313 Sherman Street. Room 723
Denver, Colorado 80203

Re: Arkansas River Instream Flow Analysis aDd Recommendation.

Dear Mr. Kowalski,

The purpose of this letter is to transmit the Colorado Division of Wildlife's (DOW) opinion regarding a
proposed 100 cfs instream flow recommendation for the Arkansas River below Pueblo Reservoir in Pueblo
County. The 100 cfs instream flow recommendation is a result from preliminary field work investigations
performed by now and discussion between several parties, including the Colorado Water Conservation '.
Board (CWCB) staff and the City of Pueblo. The CWCB requested the DOW to collect instream flow data
and provide them with an opinion regarding the benefits of such a recommendation. Because this was an
expedited request, the amount of time for field work was limited. With more time, more in-depth studies
could have been performed on this very hydraulically complicated stream reach. However, the DOW has
been able to collect a sufficient amount of data at four different cross-sections located throughout the stream
reach. As discussed in more detail below, DOW has reviewed the data collected to date and believes a 100
cfs year-round instream flow would preserve the natural environment to a reasonable degree, as long as the
stream environment continues to benefit, to some extent, from the higher summertime flows provided by
downstream senior water rights.

General Backeround
The subject of this instream flow analysis begins at the outlet of Pueblo Reservoir and extends downstream
to the confluence with Fountain Creek. This segment of river is located within the City of Pueblo and is
greatly affected by its urban setting. The urbanization of the riparian corridor has an affect on the natural
characteristics of the stream environment and the stream hydraulics. The resulting modification of the
stream hydraulics and natural hydrology has had an affect on the natural streambed composition and
hydraulic geometry. The existing stream channel has been designed and lor altered to convey large volumes
of water efficiently without flooding. This segment functions as an urban corridor stream, and must be able
to handle a higher frequency of greater magnitude stonn events due to the large amount of impervious areas
located within the watershed. To accomplish this task, urban streams generally have a limited number of
obstructions located within the channel that provide cover or holding areas for fish. In general, to improve

DEPARTMENT OF NATURAL. RESOURCES, Russell George, Executive Director
WllDUFE COMMISSION, Jeffrey Crawford, Chair. Tom Burke, VICe Chair. Ken Torms. Secretary
Members, Bernard Black . Rick Enstrom. Ph~ip James. Claire O'Neal. Brad Phelps. Robert Shoemaker
Ex Officio Members, Russell George and Don Ament

~.