WMOD00398

• Project Name: Project Skywater
• Title: Precipitation Management and the Environment - An Overview of the Skywater IX Conference
• Date: 9/1/1977
• Weather Modification - Doc Type: Report

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Effective means for obtaining representative samples of air, water, and soil are needed for
monitoring. Methods to determine if precipitation comes from a seeded storm could clarify some
legal problems.
Some industries use differential crystallization of minerals by solar evaporation in brine ponds
as an extractive process. Concern that silver from cloud seeding inhibits separation of the desired
chemicals appears unjustified.
No seeding agent other than silver iodide was seen as raising important issues or as requiring
any action other than possibly monitoring eutrophication of public water supplies in an area of
heavy use of nitrogenous hygroscopic agents.
Conclusions.-Environmentally, the use of seeding agents should have no significant effect and
there is no evidence of unacceptable changes in biological systems due to them. However, users
should be aware that new studies may alter this assessment. Although cloud seeding represents
only a small fraction of environmental dispersion of silver, other dispersers are not likely to
support research in the field.
Recommendations.-A running review of pertinent literature should be undertaken. Possible
concentrations of and biological responses to silver should be monitored. Analytical methodology
for silver should be improved. Chemical, physical, and biological concentration phenomena and
the effects of any such concentration on organisms should be studied. The possibility that silver
may potentiate other metals should receive attention. Cooperative studies with the Photographic
Manufacturers Association and the Silver Users Association should be supported.

Environmental Overview (Dr. John Marr, Convener)

Within the context of an "ecosystem" overview, the following issues were identified and
discussed.
The terminology problem.-An issue is a controversy with implied uncertainty as to which,
among alternative feasible outcomes will eventuate, while a problem is generally an issue with a
unique solution. Environment implies focus on the surroundings of a place or object, while
ecosystem implies living matter together with what affects its form and function. In discussing
these matters, it is important to use simple terms in a consistent manner. A glossary of
precipitation-management terms would be useful.
Possible initiation of long-term trends.-Even though precipitation augmentation might
initially increase ecosystem productivity, this might be followed by a decrease. Possible causes of
such a decrease include leaching of nutrients initially in the soil to horizons no longer available to
plants; invasion of grassland by shrubs and trees, reducing forage production; an increase in
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fungus and insect pests; and erosion which, once accelerated by increase'd precipitation, might
continue at a higher rate. All theoretically possible long-term changes should be monitored.
Linkage with conservation activities.-Precipitation management needs to be linked to water
use through management coordination that embraces agriculture (including irrigation
technology), forest watersheds, and storage management (evaporation reduction).
Regional concept.-If results of ecological studies are to be extrapolated from one site to
another, stratification is needed that permits the landscape to be partitioned according to its
important properties. In declining order of importance, the important properties are climate
(principally precipitation); geomorphic class (according to a classification such as that of

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