CRWaterAvailabilityScope - Final Phase I Scope

• Title: Water Availability Study of Colorado River and Tributaries Phase 1 Scope of Work
• Date: 10/19/2007
• Author: CWCB
• Interbasin CC - Doc Type: General Resources

At various locations within the state initial water avai lability w ill be evaluated using the
following formula :

Water Availability = Physical Supply - Water Use (includes downstream demands)

The above factors can be modified using various assumptions and techniques. It is the
application of these assumptions and techniques which dramatically increases the
complexity of the analysis. In addition, assumptions/techniques in considering the
following factors also affect the precisions and accuracy of the analysis :

method s for determining consumptive use

legal interpretations which may constrain availability

characterization of shortages to current demands

characterization of current demand patterns/project operations

time steps (instantaneous, daily, monthly, yearly, multiyear) associated with
demands

reliabil ity considerations in meeting a set or sets of demands (risk)

assumptions regarding temperature and the impacts of temperature changes on the
timing and amount of consumptive uses and return flows

assumptions regarding precipitation (timing, amount, form)

The following scope of work includes assumption s regarding how some of the above
factors will be considered and evaluated (in some
case it may be overly speculative to make
Study Purpose …… .…….……… …… 1
Study Authorization…….… …… …… 2
assumptions). It is important to note that there is
Overall Study Phases………………... 3
no single right or wrong a nswer. In addition, how
Phase I Goals/Organization…………... 5
an individual views the risks associated with General Guidelines for Study……...... 5
Phase I Technical Approach……….... 7
future use will in large part correlate with the
Phase I Schedule…………………….. 1 5
extent to which that individual ’s current demand
Phase I Budget………………………. 1 5
is met (i.e., those users who se current demand s
are not being met may take on considera bly more risk then those who se current demands
are fully met). What is important is to have general agreement on how Colorado should
approach answering the question of how much water we have available for future water
needs.

STUDY AUTHORIZATION

Senate Bi ll 07 - 122 directs the Colorado Water Conservation Board (Board) to evaluate
water availability in the Colorado River and its tributaries. SB 07 - 122 provides up to
$500,000 for the conduct of the study with no set deadline for completion. The language
in th is bill als o indicates that:

The Board shall work in full consultation with, and the active involvement of , the
B asin R oundtables (BRT),

The Study shall consider current and potential future in - basin consumptive and
non - consumptive needs ,
Colorado River Water Availability Study Scope 2 October 1 9 , 2007