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

environmental impacts. If on the other hand, a
hail-suppression program that overlapped a precipitation-
management program were to result in accumulations of
silver at many times the rate resulting from precipitation
management alone, then consideration of environmental
impacts would be dominated by the hail suppression program.
The effect of precipitation management in aggregation with
hail suppression would then be to shorten somewhat the
period during which accumulation could continue without
incurring adverse impacts, providing that such impacts
would ensue at all.' [1, p. B-90J

'The 1976 Skywater IX Conference, Preci pitat i on Mangement
and the Environment, included a 2-day meeting of a study
group that was preparing a report to the National Science
Foundation on the status of research on seeding agents.
The Skywater IX Conference report [16J includes the report
of the seeding agents' group following its interaction with
other Conference workshops. Thi s report states: "Based on
pur e 1 yen vir 0 nm e n tal con sid era t ion s (n 0 t con sid e r i n g
relative _economics and changes in delivery system capabil-
ities), use of si"lver iodide as a nucleating agent should
have an insignificant impact on the environment. This is
based on the following factors: - No biological evidence is
available to date to indicate that unacceptable changes
might occur in biological systems which are of concern to
the general public. - The relatively minor contribution of
silver released to the environment by weather modification,
in comparison with other sources of silver.'

"The seedi ng agents study group 1 ater pub 1 i shed a report under
the National Science Foundation grant entitled 'Environmental
Impacts of Artificial Ice Nucleating Agents' [51J. The report
was recently summarized in a review by Warburton [52J, who
states:

'The book's title implies we are dealing with the effects
of ice-nucleating agents upon the environment, whereas, as
the authors ably point out, there are few observable
effects from such chemical compounds (part icul arly silver
iodide); most of the effects are produced by ionic silver
or the bisulphides at concentrations generally not achieved
by ice-nucleating agents released into the atmosphere by
man. It is regularly noted in the chapter summaries that
little or no observable effects have been detected on the
environment from the highly insoluble ice-nucleating agents
commonly used in weather modification.'

"Warburton continues:

'It is very reassuring and important to note the conclu-
sions reached by K'\ein from the discussions in Chapter 12,
Effects on Humans (from ice-nucl eati ng agents di spersed

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