Weather Mod Report - 1977

• Project Type: General OWC
• Project Name: Weather Modification
• Title: "What Should Colorado Be Doing in Weather Modification"
• Date: 11/9/1977
• County: Statewide
• Water Conservation - Doc Type: Final Report

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of direct impacts on the natural environment of additional snowpack in the
mountainous areas. I shall follow the outline drawn up by the Skywater IX
environmental workshop groups which spent a week, just about a year
ago, summarizing our present state of knowledge on this subject.

The first topic was effect of increased snowpack on abiotic aspects of the
mountain environment, including precipitation itself as an environmental
element, then effect of added snowfall on microclimate, erosion, avalanches,
and water yield, and finally effects on fluvial geomorphology and water
quality. Effect on the duration of snowcover is expected to be the
most readily detectable. Effects on erosion, fluvial processes, and
sediment yield might become apparent but would be very difficult to
distinguish from the much larger effects attributable to summertime
precipitation.

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Based on research on avalanches conducted by the U.S. Forest Service and
the Institute of Alpine and Arctic Research of the University of Colorado
showing that avalanche hazard is determined by details of snowpack
structure and within-storm snow accumulation, and that the major avalanche
chutes run during every large storm, additional snowfall attributable
to precipitation augmentation was not seen as having a significant
effect on avalanche hazard to life, property, or the environment. On
the contrary, the improved understanding and forecasting of avalanche
hazards derived from this research, which was stimulated by the prospect
of snowfall augmentation, was felt to have decreased the overall avalanche
hazard.

Vegetation, the principal link between the abiotic environment and higher
life forms, was the second topic. Extent and duration of snowcover were
identified as the key factors, and a need for better information as to
where added snow will fall, how it will drift and accumulate, and how
these processes would affect snowcover duration on a local scale is of
prime concern. Within areas of late-lying snow, some change in species
composition is to be expected, tending to favor the rarer plants.
Elsewhere, added snowfall is expected to increase the general level of
vegetational productivity. No salient adverse effects are to be
expected.

The workshop group expressed high concern for offsite impacts on
vegetation arising through broad-scale changes in land-use that might ensue
should the added water supply result in much conversion of rangeland to
cropland. However, since this effect is mediated through the socio-
economic and political environments, I shall not consider it further
at this moment.

The workshop on animals considered the web of effects through habitat
and food on particular animal species identified as indicators of general
ecological effect. In the mountain environments of the Upper Colorado
Basin, the most likely effects are considered to arise from restriction to
movement and greater difficulty of access to food for elk, rnuledeer, and sage
grouse. Adverse effects on pronghorn would be expected if much rangeland

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