Conducting the Environmental Impact Analysis and Assessment - Environmental Impact Analysis: Process and Methods - page 179

and the installation of these large facilities (up to 1200 hectares each) necessary
for such an extensive range of coverage was considered a federal action with
potentially significant impacts requiring NEPA compliance and an EIS. The
investigation of the affected environment for the transmit OTH radar in Modoc
National Forest (northeastern California) was focused on the critical issues and
demonstrates an imaginative and creative approach that can provide insight to
structuring affected environment investigations for other situations.
The preferred location for the Modoc National Forest OTH transmitting
radars was in potential conflict with two important and environmentally sensi-
tive resources identified during scoping: large mammal (pronghorn antelope
and mule deer) migration and Native American cultural resources. Thus the
description of the affected environment had to address the existing migration
patterns of the large mammals and the cultural resource characteristics of the
area. The mandatory first step of the investigation (literature review) identi-
fied important information on the two critical resources such as the type of
cultural sites to expect and a general east-west migration pattern for both the
antelope and mule deer. The animals traversed the study area in the spring on
the way to their feeding or breeding grounds and in the fall on the way to their
wintering areas. They were present in the study area only for these very short
migration periods, but their continued survival was dependent on successfully
migrating through the area twice each year. However there was no site-specific
information available for their exact migratory routes, thus an investigation of
the existing conditions of these resources had to be designed and implemented.
The standard methods to describe large mammal migration were not com-
patible with the schedule of the environmental impact analysis; thus creative
measures had to be derived. The common methods for mammal migration
investigation were real-time observations (via on-ground spotters and aer-
ial surveillance) and radio tagging and tracking of the animals. Both these
methods required multiseason investigations, but the environmental analy-
sis had to be completed before fall and spring observations could be con-
ducted. After consultation with stakeholders, including the Forest Service
and state fish and game wildlife specialists, an effective and efficient method
that did not require real-time observation during both migration seasons
was developed. The entire study area (over 2000 hectares) was surveyed by
biologists (primary graduate students) by walking regularly spaced tran-
sects. Although the survey was conducted during the summer, when there
were no large mammals in the area, the migration routes were discernible by
fecal pellets left by the antelope and deer as they migrated. The pellets left
by the two species were very similar, and it was not practical to determine
in the field which were left by which species. But given the objective and
the narrow focus of the investigation, it did not matter because the objective
was to ultimately understand the impact of the radar placement on large
mammal migration, independent of species. Although the method was labor
intensive, it could be conducted within the schedule of the environmental
impact analysis, and it proved effective in identifying the migration routes.