Colorado River Basin Activities and Issues - 5

• Title: Colorado River Basin Activities and Issues
• Date: 5/9/2007
• IBCC - Doc Type: Needs Assessment & Technical Support

Colorado River Basin Activities and Issues

On Febmary 2,2007, the Interbasin Compact Committee (IBCC) discussed the Colorado
River Compact. After the presentation of background information, a free-flowing
discussion began to frame the big-picture issues facing the State. This memo offers a
framework for approaching the issues on the Colorado River and presents some
discussion points for moving forward.l

The issues on the Colorado River can be framed by three key questions:
1. How much water is remaining in the Colorado River and its tributaries for use
within the State?
2. How would a call by the lower basin states be administered within Colorado?
3. How should the State of Colorado approach full development of the Colorado
River?

These three questions are interrelated, but provide a way to think about the big-picture
issues. The Interbasin Compact Process cannot definitively answer these questions.
However, it can present a framework within which the various decision makers address
these questions, and provide the necessary public input and transparency.

Question One: How much water is remaining in the Colorado River and its
tributaries for use within the State?

Summary
Gauged river flows and calculations of Colorado's current consumptive use indicate that
between 450,000 ac-ft (or less) and 1,200,000 ac-ft of Colorado River water may be
remaining in the river and its tributaries. The lower end of the estimate takes into
consideration water that is available under a multiple year drought. The upper end of the
estimate reflects the maximum legal availability to Colorado under the Colorado River
Compact.

Eric Kuhn, General Manager of the Colorado River Water Conservation District, framed
the question to the IBCC as follows:
An assumption ~ften made in hydrology is that thefltture will look like the past.
This assumption involves examining historical data on c1imatolo:s'Y, hydrolo:s'Y
and river.f7ows, and assuming that the same pattern ~ highs, lows, average
raiJ?fall, mix ~fwet and dlY years, etc. ~ will continue into thefltture. Is that a
good assumption in today 's world?

Many studies suggest the world is getting warmer, which could trigger an
increase in consumptive use. In a warmer world, the same precipitation would

1 This memo ,,'as developed from the discussion at the 2/2/07 IECC meeting and subsequent conversations.
It is only meant for discussion purposes. should only be attributed to the author. and does not reflect any
decisions or policy by the State of Colorado.