WSPC04785

• File Number: 8283.200
• Description: Colorado River Computer Models - Colorado River Decision Support System ‎(RAY)‎
• State: CO
• Basin: Western Slope
• Date: 1/1/3000
• Author: CWCB
• Title: CRDSS - Task Memoranda, CRDSS Scenarios
• Water Supply Pro - Doc Type: Report/Study

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3. OVerview of Problem Solving Procedure

Decision variables

Depending on intent, this scenario may be carried out using two distinct
approaches each involving different decision variables. Flexibility of the
modeling procedure allows formulation of the problem in either manner.

1) The first approach is to establish a desired instream flow target at
some location(s) in the river basin and then determine the impacts such
a flow proposal would have on existing (and proposed) water rights. The
decision variables here are the target instream flow amounts,
priorities, locations, and timing.

2) The second approach would be to establish the list of water rights,
and then determine whether the target instream flows could be met at
some location. The decision variables here are the water rights
established as active for the simulation trial. These may include
conditional water rights which may be said to be a development plan.

The amount of Colorado's entitlement which has not been developed
(magnitude and timing) is a derived quantity based on some analysis of the
amount of water available for development (i.e. the difference between the
amount of water leaving the state and the (projected) amount used).

Step-by-step review

A solution approach to this scenario involves a procedural kernal
summarized as follows for the two approaches:

(1) Instream flow target approach

(a) Determine amount of water at a selected location.
(b) Determine how much water is available for development.
(c) Specify instream flow targets (location, magnitude, timing).
(d) simulate the instream flow targets and water rights situation.
(e) Assess the potential impacts of the flow targets on existing and
conditional water rights.
(f) Run several scenarios and score impacts.
(g) Prepare a summary report.

(2) Development plan approach

(c) Define development plan(s) and determine incremental consumptive
.use.
(d) Simulate the development plan and existing water rights situation.
(e) Assess potential impacts of the development plants) on existing
water rights (and/or proposed instream flows) .

Steps (a) and (b) are analyses preparatory to assessing the impacts of
instream flows and/or development plans on Colorado's compact entitlement.
(These are not necessary if only a development proposal's impacts on other
water rights is desired.) These steps involve determination of the amount of
water available at a selected location, followed by determination of the
amount of Colorado's entitlement which has not been used. For a state-wide
assessment, these locations would be the gages closest to the state border;
each of the four basins would be addressed, one at a time. Since there is
currently no administrative mechanism for prioritizing development between
basins this would be left to the judgment of the user.

Steps (c), (d), and (e) are the procedural kernals for the two
approaches. Steps (f) and (g) involve repetition of the kernal procedures for
several scenarios, scoring of impacts for comparison purposes, and reporting
the results.