7850

• UCREFRP Catalog Number: 7850
• Author: Hydrosphere Resource Consultants.
• Title: Yampa River Basin Recommended Alternatives, Detailed Feasibility Study
• USFW Year: 1994.
• USFW - Doc Type: Draft.
• Copyright Material: NO

Executive Summary
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Table S-1
Preliminary* Flow Recommendations at Maybell
Month Reco mmended Flow (cfs)

October 204 (50% exc.)
November 255 (50% exc.)
December 228 (50% exc.)
January 217 (50% exc.)
February 256 (50% exc.)
March 498 (50% exc.)
April
May
June **
July 999 (50% exc.)
August 220 (50% exc.)
September 91 * * * (50% exc.)
* Still under review by U. S. Fish and Wildlife Service
* * Percentile which occurs naturally in any given year.
* * * The 50% exceedance flow for September is 91 cfs based on water availability
considerations associated with the assumptions in the Yampa River Basin Model. The
Service recognizes that the conditions modeled are based on worst case assumptions
and that flows are not likely to drop to this level in the near future. If this flow level
were to regularly occur there may be a need to secure augmentation sources to
maintain or enhance late summer flows.
Current Conditions Analysis
The basin model was then used to characterize streamflow and reservoir storage
conditions under current levels of development in the basin. The modeled water demands
reflecting current development are termed "current potential" demands. They reflect
somewhat more intensive water consumption by existing users (though not more than has been
observed in past dry years) and include "backcasting" adjustments to impose current levels of
demand over the entire historical study period. Based on data obtained from Division 6 of the
State Engineer's office, these "current potential demands" are believed to reflect an average
annual basin water consumption of roughly 121,000 of/yr.
The results of this model scenario indicate that, with the exception of some agricultural
demands on tributary streams, current basin water demands are fully met without very much
draft on existing storage. Only in dry years are the contract pools in existing reservoirs relied
on to meet demands.
' Flow conditions at Maybell resulting from this model scenario were also examined and
are shown on Figure S-1. Median flows at Maybell are somewhat higher than the preliminary
flow recommendations because the flow recommendations reflect additional depletion
' assumptions not included in the current conditions scenario. The 75th-percentile exceedance
flows give an indication of flow conditions that would be expected in dry years.
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