WMOD00264

• Applicant: USBR
• Sponsor Name: CWCB
• Project Name: Analysis of Cloud Seeding Potential
• Title: Potential Water Augmentationfrom Cloud Seeding in the Colorado River Basin
• Prepared For: CWCB
• Prepared By: USBR
• Date: 12/1/2005
• State: CO
• Weather Modification - Doc Type: Scientific Study

Final Online Version, December 2005; modified
version to be submitted to April 2006 Journal of
Weather Modification

Potential Water Aug:mentation from Cloud Seeding:
in the Colorado River Basin

Steven Hunter, Steffen Meyer and Ra Aman
Bureau of Reclamation Technical Service Center, Denver

1. BACKGROUND

Seeding of orographic (mountain) clouds in the cool season has been done in the
Upper and Lower Colorado River Basin since the 1960s, on an operational and research
basis. Several studies have been done in that time to estimate the potential water
augmentation from seeding in the basin. The following are some of the older such
studies and their estimates of water yield, as cited in a Bureau of Reclamation report of
19801:

Table 1. Previous water yield estimates from cloud seeding in the Colorado River Basin

Source Dates Water Yield Estimates (Acre-ft)
Bureau of ReclamationZ 1967-1968 1,870,000
Stanford Research Institute3 1971-1972 1,150,000*
North American Weather 1972-1973 1,315,000 (liberal)
Consultants (Twelve Basin 903,000 (conservative)
Investigation )4

* Figure from this document is halved because it assumed a 20% increase, whereas today the often
accepted increase is 10%

These figures are for seeding all target areas in the basin, with areas selected
based on the differing criteria of each study. Since these studies are over 30 years old, it
was desired to update them with more recent information. Also, motivation was added
by the letter 25 August 2005 from the seven Colorado Basin states to Interior Secretary
Norton. This letter requested a long-term plan for operating Lakes Powell and Mead
during hydrologic drought, and included a recommendation that Reclamation develop a
plan for water augmentation through cloud seeding. Also, funding and context for the
current work were provided by the Colorado Water Conservation Board's (CWCB)
"Winter Storm Climatology" study, of which Reclamation had a part.

2. AUGMENT A nON ESTIMA nON PROCEDURES

We assumed a 10% increase in April 1 snow water equivalent (SWE) in existing
and potential target areas, with SWE provided by the Snow Data Assimilation System
(SNODAS5). The SNODAS consists of a spatially-distributed snow energy and mass
balance model, updated with all available snow water equivalent, snow depth, and snow
cover (from surface, aircraft, radar, satellite) data. Model outputs include SWE, snow
depth, snowmelt, pack temperature, and sublimation. Daily and historical model output
for the state of Colorado may be found at this web site6. The output has been available
nationwide since October 2003, and for some areas before that date. Therefore data exist

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