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

forest-meadow and al pi ne-meadow 1 ocat ions. Prel imi nary results
indicate that heavy or late-lying snow tends to shift the
growi ng season to a 1 ater date, but not to affect its 1 ength.
In delayed seasons, species were observed to complete their
growth cycles and set seed. In the alpine setting, certain
species subjected to artificial snowdrifts produced seed of
reduced germinability. It is tentatively concluded that the
Skywater experimental program of wi nter snowpack augment at i on
will have no discernable impact on herbaceous vegetation."
[2, pp. 3-104, 3-105J

The Skywater Programmatic St,atement concluded:

"No significant impact on the overall productivity of the
herbaceous community is expected. The mai n reason for thi s
expectation is the finding that species composition is deter-
mined principally by minimum soil moisture during the growing
season, and that productivity of different species in different
settings is influenced by a variety of factors, including a
sl i ght del ay in snow rel ease data and a del ay in the date of
exhaustion of winter moisture.

"Other outputs of the~ Skywater program such as instrument
and equipment installlations, travel, and seeding agents,
are expected to have no significant impact on herbaceous
vegetation." [2, p. 3-108J

Long-term monitoring of the responses of vegetation to incremental
precipitation increases will be required to determine whether species
composition and productivity will be significantly affected.

Studies of the effects of precipitation increases on large and small
mammals were undertaken in the Medicine Bow Ecology Project [14J, the
Sierra Ecology Project [15J, and the San Juan Ecology Project [10J.
In addition, Montana State Univers ity surveyed prev i ous research
on the effects of weather components on big game. "Section 2,
Ecological, Wildlife and Biocommunities,1I of this report series
states:

"Various weather components seem to influence the activities of
many bi g game speci es: 1. game speci es move to areas of the
most available forage; 2. game species move to areas of the
most nutritious forage; 3. relative humidity affects the length
of rest periods which are longer on more humid days and shorter
on less humid days; 4. ,animals rest in areas away from wind; 5.
precipitation, unless accompanied by wind, does not affect the
activity of game species; 6. game species use higher elevation
ranges during dry summers; 7. game species are more observable
during dry summers because of lack of cover and search for
preferred food species:; 8. winter snows decrease the avail-
ability of total range" cover, and food; 9. low temperatures
decrease act i vit i es of game speci es; 10. wi nds of 15-25 mph
and low temperatures cause game species to feed later in the

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