PROJC00189

• Contract/PO #: C150006
• Contractor Name: Palisade, Town of
• Contract Type: Loan
• Water District: 72
• County: Mesa
• Bill Number: HB 95-1155
• Loan Projects - Doc Type: Feasibility Study

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The second report was prepared in 1997 by Hydrosphere Resource
Consultants of Boulder. Two methods were used in that report for
calculating firm yield. The first was a regional regression relationship
developed by USGS for western Colorado and which Hydrosphere applied
to the Palisade watershed. The second method involved the use of recorded
stream flow data compiled by Powderhorn Coal Company at gauging
stations on Rapid Creek.

The Hydrosphere methodology appears to be more comprehensive and more
applicable to the Palisade watershed than that used by Leonard Rice;
therefore, the information from that report will be summarized herein.

3.

l{ydro~here's Methods for Calculating Firm Yield

The following is a summary of the two methods used by Hydrosphere and
the results they obtained. A more complete description is in the
Hydrosphere report included in the Appendix.

a. Method A: RE:gional Rl:gression.

This method is based on the USGS (1985) report entitled "Estimation of
Natural Streamflow Characteristics in Western Colorado", Kirchener,
J .E., et.al. The Palisade watershed is located in two separate
hydrological regions (as defined by the USGS report), the mountain
region and the northwest region. The USGS report has calculated
regression equations for each region. Using criteria in the USGS
report, Hydrosphere determined which subareas in the watershed fit into
each hydrologic region and calculated yield for each subarea using the
regression equations. Adjustments were then made for flows diverted
out of the basins at the Rapid Creek Reservoirs and for flows diverted
into the basin from Kruzen Springs. Average annual yield calculated by
this method was 3622 acre feet per year.

b. Method B: Correlation with Rapid Creek Stream Flow Data.

As part of their permit from BLM, Powderhorn Coal Company is
required to monitor flows in the Rapid Creek/Cottonwood Creek
drainage basins. Flow records were available for the period from 1986
to 1993 from a flow monitoring station located below the confluence of
the two streams. The flow measurement program calls for recording
flows on a daily basis; however, there are numerous gaps in the data
due to problems with the flow measurement devices, high flows,
weather, etc. The procedure for calculating firm yield from this data is
as follows:

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