NEPA--Environmental Assessment

Silverton Grazing Risk Assessment
preferred habitat components in the allotment, and decades of historic use of the
allotment without evidence of contact with bighorns from S33, in combination result in a
rating of “Moderate Risk” for contact in the Picayne/Mineral Point Allotment.
Eureka Allotment (BLM, active allotment):
Under current management, there is only about 183 acres of overlap in the active BLM
Eureka Allotment with mapped summer range for the S33 Pole Mountain/Upper Lake
Fork bighorn sheep herd. Within this area, only about 43 acres (23%) is suitable domestic
sheep grazing range. The overlap area is a small narrow area on the east side of the
allotment.
Domestic sheep have been grazed here since prior to the Second World War. Prior to
1992, the stocking rate of this allotment was about twice what it is currently. The
permittee accesses the allotment by trucking sheep to a set of corrals just south of the
town site of Eureka, then trailing sheep into Eureka Gulch along the road.
The area of overlap with bighorn summer range is a relatively small area in the east
central part of the allotment along the north side of Eureka Gulch. Although the overlap
area is steep alpine slopes, there is little rocky terrain or talus slopes for bighorn escape
cover. Most of the terrain in the allotment is alpine meadows bisected by high ridges and
steep slopes and canyons traversing higher alpine peaks, with some patches of mature
spruce-fir forest along the South Fork Animas River canyon. Elevations in the allotment
vary from 9,800 feet to just over 13,400 feet. The allotment includes the headwaters of the
West Fork and the South Fork of the Animas River. There is good access to most of the
allotment by 4WD roads.
Elevations on the allotment vary from 9,800 feet to just over 13,400 feet. The terrain
consists of high ridges and steep slopes with canyons throughout the rugged mountains.
The allotment occurs at the headwaters of the West Fork and the South Fork of the
Animas River. There is good access to most of the allotment by 4WD roads.
The area of mapped overlap with bighorn sheep summer range in the Eureka Allotment is
generally not used by the permittee. Domestic sheep are generally grazed west of the area
of mapped overlap. The area of overlap is on the north wall of Eureka Gulch and about
1.0 mile west of the Animas River. Portions of Burns Gulch where bighorn sheep have
been detected are about 2.0 air miles northeast of the mapped overlap area. Crown
Mountain and Niagara Peak are about 3.0 air miles east of the allotment and are believed
to be summering areas regularly used by bighorn sheep. The Eureka corrals are about 1.5
air miles west of Crown Mountain, and about 0.25 mile south of and outside the S33
summer range boundary. The north half of the allotment shares its east boundary with
the Picayne/Mineral Point Allotment and the western most boundary of S33 summer
range.
Surveys for bighorn sheep were conducted by BLM employees over the past four summer
seasons, including in the area of mapped overlap, and no bighorn sheep were detected in
the allotment or near the Eureka corrals. The domestic sheep permittee has reported no
sightings of bighorn sheep in the allotment. The allotment is also heavily used by the
public for motorized recreation with an extensive network of heavily traveled 4x4 roads
and no bighorn sheep have been reported to CDOW in the area of overlap.
Summary of Risk Rating for Eureka Allotment:
Risk Rating: Alternative 2 – High
D-19