WMOD00422

• Project Name: Colorado River Enhanced Snowpack Test
• Title: CREST - Environmental Assessment and Design Phase - Finding of No Significant Impact
• Date: 4/1/1981
• Weather Modification - Doc Type: Report

II. PROPOSED ACTION AND ALTERNATIVES

The action proposed by Water and Power is to seed wi nter storm clouds in
the Rocky Mountains of the Colorado River Basin to increase snowpack,
y'unoff, and streamflow, thereby providing increased water yield to help
meet future resource demands.

Pl. No Act ion

L'nder this alternative, no site-specific activities would occur in the
Colorado River Basin resulting in a design for a Basin-wide operational
cloud seeding program. Research into physical processes within storms,
development of new instrumentation for an improved measurement capability,
and testing techniques for real-time analysis and evaluation of results
woul d continue under the current Water and Power research program budget.
This alternative presents no, additional funding requirements and environ-
mental or social impacts are not expected. Institutional arrangements for
administering additional water supplies are not needed. The disadvantages
of the no-action alternative are that weather modification as a nonstruc-
tural alternative for augmenting the Colorado River Basin water supply will
not be demonstrated as a usable alternative. Future development in the
Basin may be restricted. In order to meet the water use anticipated under
the terms of the Colorado River Compact, other methods of augmenting the
water supply would be required ultimately. Delivery of water to Mexico as
well as replacement supplies for depletions resulting from the Salinity
Control Program would be impacted.

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B. Cloud Seeding

Winter orographic clouds that are not efficient naturally can be seeded to
produce increased precipitation. Water and Power has identified five
important al pi ne and subal pi ne watersheds above el evation 9000 feet that
produce about 75 percent of the Upper Basin's runoff (see figure 1). These
areas are the best candidate subbasins for cloud seeding.

Cloud seeding nuclei will be either dry ice or silver iodide. Clouds can
be seeded by aircraft or by ground-based generators. Six high yield
Colorado River Basin subbasins, including the San Juan Basin, have been
identified as candidates for the initial and demonstration phases of the
Basin-wide seeding program. .

1. 10-year Prog~am

In this option, the initial 5-year phase allows sufficient time for
tests in two subbasins to develop the equipment, procedures, and a
design for conducting a randomized seeding program in one subbasin that
will permit statistical evaluation. Other tasks include developing
techniques for readily identifying optimum seeding conditions, determi-
ning how frequently those conditions exist, procurement and installation
of. required data collection networks and equipment, and preparation of
environmental and social impact documents, and a demonstration design.

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