WMOD00065

• Applicant: Western Weather Consultants
• Project Name: N. Central Mountains
• Date: 12/1/1979
• Weather Modification - Doc Type: Report

FINAL OPER~TIONAL SEEDING SUpLMARY REPORT
for
CENTRAL MOUNTAIN AREA

Application for a permit renewal for weather modification in
the North Central Mountains of Colorado was submitted on August
31, 1979, to the Department of Natural Resources, State of
Colorado. This matter was reviewed at a public meeting held on
October 3, 1979 before Harris D. Sherman, Executive Director,
Colorado Department of Natural Resources, at the Dillon TOwn Hall,
Dillo~Colorado.

A permit to operate the program with several changes, limita-
tions and exclusions was received on November 9, 1979. The
Steamboat Springs area was excluded from the program and the
standby programs of the Denver Water Department and Northern
Colorado Water Conservancy District were subject to decision at
the time of request for activation based on need, without the
requirement of further hearings. The beginning date for oper-
ations was set back from November 1, 1979 to December 1, 1979.
Further limitations applied to utilizing generators when the
plume might be expected to reach Leadville, Colorado and to
those generators under the wind direction conditions specified
in Western Weather Consultants, Inc. letter of October 31, 1979
and attached to the permit. The snowpack suspension criteria
were reduced to effect earlier cut off of operations with above
mean snowpacks. The effect was the elimination of 200% of mean
in January by backing up the previous criteria by one month.

The program was operationally ready by December 1, 1979 with
19 generators for the active program and 7 exclusively for the
standby programs. All of the generators were manually operated
and utilized silver iodide as the nucleating agent.

Weather systems suitable for treatment were scarce in December.
The first opportunity occurred on December 10, 1979 and the other
event for the month was on December 21st and 22nd. January pro-
vided an opportunity for 6 events and February had only one early
in the month. The drop off in February was due to snowpack
values exceeding the cut off criteria.

During the period from December 1, 1979 through February 29, 1980
cloud seeding occurred on 11 calendar days out of the total 91
day period of the program. These eleven days occurred in 9
separate events or operations. Total operations for the program
amounted to 410 hours of generator seeding time, which dispensed
2,650 grams of silver iodide. Precipitation occurred frequently
enough from late December through mid February with many of the