PROJ01750

• Contract/PO #: 04000000017
• Contractor Name: Northwest Colorado Council of Governments ‎(NWCCOG)‎
• Contract Type: Grant
• Water District: 0
• Loan Projects - Doc Type: Contract Documents

Upper Colorado River Basin Study
Scope of Work

October 1, ! 998

fa<;ilities of in-basin water users will be provided to the Management Committee. This
information will be utilized in P ACSM and for scenario modeling to evaluate impacts to
in-basin water rights and users.

4.6 Review P ACSM West Slope Operations

1bree half-day meetings will be held with Denver Water staff to review and understand
the operational, water rights and hydrologic assumptions in the West Slope portion of
Denver's PACSM model. These meetings will involve Hydrosphere, Denver Water staff
and other sponsoring parties. A memo documenting the results of these meetings will be
provided to the Management Committee.

4.7 Specify P ACSM Modeling Scenarios

A number of hydrologic scenarios will be explored in this Study, including today's
conditions and future scenarios. These scenarios will be evaluated for wet, dry and
average years based on a 1947-1991 hydrologic record. The existing and future scenarios
may have numerous areas of uncertainty that must be agreed upon by the sponsoring
parties and specified prior to modeling of the scenarios.

For example, Denver Water has a PACSM model run depicting the operation of Denver's
system at an existing average annual demand of265,000 AF over the 1947-1991 period
of hydrologic record. The output from this run could reasonably be used to represent
"today's conditions". However it is not clear how Denver represents certain aspects of its
system and other systems in this run. For example, are modeled exchanges out of
. Wolford Mountain Reservoir occurring at significant levels? Are Windy Gap diversions
modeled at existing levels or full levels? 'Nhat interpretations are embedded in the
modeled operation of Green Mountain Reservoir? Therefore, a series of two meetings is
anticipated to specify the assumptions and scenarios to be considered in terms of demand
levels, components and major assumptions. Prior to the m~etings Hydrosphere and the
Management Committee will develop a list of factors to consider that bear upon these
scenanos.

Given the Study budget and schedule, a reasonable limit must be set regarding the
number of scenarios to be analyzed during Phase II of the Study. To facilitate future
problem solving discussions under Phase III of this project many future assumptions will
be lumped or weighted into two modeled scenarios: one that relies more heavily on
Denver's Grand County collection system and one that relies more heavily on their
Summit County collection system. An initially proposed list includes the following:

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