Cherry Creek Valley Risk Assessment Final Report

• Project Type: Ag/Muni Grant
• Contract/PO #: C153776
• Applicant: Cherry Creek Water & Sanitation District
• Project Name: Wabash Risk & Reliability Assessment Project
• Title: Wabash Reservoir Complex Risk/Reliability Assessment Project
• Date: 6/1/1999
• County: Denver
• Water Conservation - Doc Type: Final Report

Hydrologic Technology Fax:[phone]

Jl.ln 18 '99

7:22

P.04

The average annual yield of the Wabash Complex as originally designed with 419 acre-feet of
storage capacity is projected to be 276.acre-feet per year. This yield reflects operations based
upon meeting an irrigation demand of 325 acre-feet per year from 100 acres of irrigated turf
grass. If constructed to its decreed capacity, the water supply from the jWlior storage rights is
projected to meet approximately 80% of the design demand.

MWlicipal water supply projects have traditionally been rated based upon their firm yield. Firm
yield is defined as the lowest annual yield of a water supply project over a defined water supply
planning period. As measured against this definition, the Wabash Storage Complex has little or
no firm yield. The coupling of the jWlior water rights with groWldwater from the Denver basin
aquifers allows for the development of a water supply system that can meet demands on a
reliable basis.

During the adjudication process, die District developed a daily operations model to determine
the probable yield of the storage system. The yield model utilizes climatic data and urban runoff
estimates to project divertable flows in Cherry Creek. Daily river calls under Colorado's priority
system are them imposed to determine when water is available for storage.

WABASH RESERVOIR COMPLEX
YIELD I CAPACITY ANALYSIS

250

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100 200 300 400 500
Total Storage Capacily (AF)

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Figure 2. Wabash Yield Capacity Curve

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The District's yield model
was modified for this
project to help determine
the risk and reliability
associated with changes in
the total storage capacity
of the Wabash Complex.
The goal of this project
was to determine if
increases or decreases in
the storage capacity will
significantly affect the
average annual yield of the
project

Figure 2 summarizes the
modeling results for
various storage
configurations for the
Wabash Complex. If the
project is constructed to its
decreed capacity, the
storage system will be able