Durango RICD, Supplement to My Expert Report of December 29, 2006

• Description: Durango RICD
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 2/20/2007
• Author: Randy Seaholm, CWCB
• Title: Durango RICD, Supplement to My Expert Report of December 29, 2006
• Water Supply Pro - Doc Type: Board 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
MEMORANDUM
TO: Susan Schneider
Colorado Attorney Generals Office
FROM: Randy Seaholm
Chief, Water Supply Protection Section
DATE: February 20, 2007
SUBJECT: Durango RICD, Supplement to my expert report of December 29, 2006
This supplements my expert report of December 29, 2006 as a result of my further
review of Durango's expert reports and their supplemental and rebuttal reports
related to hydrologic conditions, water use and compact considerations in the basin.
IS I would like to continue to reserve my rights to modify and supplement this report as
further information becomes known to me.
and therefore the ability to divert at the Durango Pumping Plant is limited to 600 cfs.
Furthermore, the decree contains a condition that will further limit diversions at the Durango
Pumping Plant. That condition will, "limit diversions at the alternate points of diversion on the
Animas River to the amount of water in priority that could have been diverted at the original
point of diversion at the Teft Diversion Dam in order to ensure that injury will not occur to
existing decreed water rights." These decree limitations and the assumptions used to determine
the environmental impacts in the FEIS would appear to limit ALP diversions sufficiently so as
Bill Ritter, Jr.
Governor
Harris D.
Sherman
Executive
Director
Animas -La Plata Proiect Water Rights and Operations: Pursuant to the decree
in Water Division 7 Case no. 80CW237 the Durango Pumping Plant is an alternate Rod Kuharich
point of diversion for several conditional water rights described therein, which CWCB Director
diversions total 760 cfs. Even though there are 760 cfs of decreed water rights that
identify the Durango Pumping Plant as an alternate point of diversion for those Dan McAuliffe
rights, the decreed capacity of the Durango Pumping Plant is identified as 600 cfs Deputy Director
not to cause the Animas River to become overappropriated.
Hydrologic Calculations — Skew Factors: While USGS Bulletin 17 -B specifically describes
procedures for evaluating flood -flow frequencies using the log- Pearson type -III distribution, the
log- Pearson type -IIII distribution is not limited solely to use in flood -flow evaluations. It is one
of several distributions that can be used for fitting a distribution to data. The "Frequently Asked
Questions of FAQ's" for Bulletin 17 -B state: "Bulletin 17 -B was written for analysis of annual-
maximum peak flows... nonetheless, the Bulletin- l7 -B procedure will provide a mathematical
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