Free Flow

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ater

ducation

and

nstitutional

evelopment

throughout the basin. The study aimed to identify potential supply

and demand imbalances facing the Colorado River basin within the

United States over the next 50 years, and to explore options and

strategies for resolving those imbalances. The study is the most

comprehensive effort of its type to date and was designed around

four major components: future supply (hydrologic conditions),

future demand, evaluation of options and strategies, and vulner-

ability analysis.

Given the size of this undertaking, a consultant team that included

private sector firms CH2M Hill, Black & Veatch and the RAND

Corporation assisted throughout the three-year effort, providing

technical expertise, analysis and report production. Stakeholder rela-

tionships and technical tools were critical to the study’s success. For

many of the study facets, multi-stakeholder work groups convened

to develop consensus on complex topics. Incorporating major view-

points from various stakeholders resulted in creative alternatives,

which benefited the study overall.

The first phases of the study were water supply and demand

assessment. A scenario planning approach was employed to consider

the full range of possible futures, rather than just attempting to

determine what was most likely to occur. This produced several

scenarios for both supply and demand. When coupled, the various

combinations of supply and demand scenarios represent a broad

range of possible futures.

Ultimately, four supply scenarios were agreed on. The

scenarios reflect hydrologic conditions based on:

• paleo reconstructed (tree-ring) streamflow

• gauge flow from the last century

• a hybrid of reconstructed and gauge flow

• modelled future conditions using data from climate

model projections.

Each scenario has unique characteristics regarding

mean flow, variability and drought (surplus) magnitude

and persistence. Although stakeholders were familiar

with several of the scenarios from previous processes,

care was taken to dedicate sufficient time to introduce

and explain new hydrology data and methods. This

helped build stakeholder confidence before proceed-

ing with other study phases. Stakeholder interest and

investment in understanding these new approaches

were equally important to this process.

Demand scenarios were rooted in a storyline devel-

opment approach. Collectively, through discussions,

narratives of possible future demand conditions were

crafted, considering factors such as the economy, popu-

lation growth and location, environmental awareness

and agricultural practices. Appropriate stakeholders then

The Colorado River is the force that carved the Grand Canyon and the lifeblood for communities, wildlife and recreation areas

Image: Lori Warren, Black & Veatch