watervulnerability

Sawtooth National Forest Watershed Vulnerability Assessment, Intermountain Region (R4)
Geomorphic Integrity
Rating determinations are based on the
ability of subwatershed soil-hydrologic
conditions to function as a sponge-andfilter
system to absorb and store inputs
of water, and on geomorphic resilience
of streams, and riparian and wetland
areas. Both natural and anthropogenic
disturbances were used to estimate
existing geomorphic conditions of each
subwatershed.
Subwatershed is in
good condition, near
or at properly
functioning condition,
and has low risk from
further disturbance.
165 Assessing the Vulnerability of Watersheds to Climate Change
Subwatershed is in fair
condition, functioning
at risk, and has
moderate risk from
additional disturbance.
Allotments No allotments Sheep/Goat allotments
and less than 25% of 6 th
Field in Cattle/Horse
allotment
Equivalent Clearcut Acres 20%
Table 2. Indicators and criteria used to determine threats to aquatic resources
Figure 6. Bayesian belief network for determining overall
threat level for each subwatershed on the Sawtooth NRA.
Subwatershed is in
poor condition, not
properly functioning,
and has high risk
from additional
disturbance.
Greater than 25% of
6 th Field in
Cattle/Horse
allotment and
Sheep/Goat
allotments present
Figure 7. Composite threat rating for subwatersheds in the Upper
Salmon subbasin on the Sawtooth NRA. Red areas have the most
threats, yellow areas have moderate threat levels, and green areas
have low threat levels.
After each indicator was rated (low, moderate, or high), outcomes were entered into a Bayesian belief
network to determine a composite threat rating for each subwatershed within the Upper Salmon subbasin
on the Sawtooth National Recreation Area (Figure 6). Threat ratings were used later in this analysis to
determine bull trout persistence. A key assumption in this analysis is that subwatersheds with a higher
composite risk rating would be more at risk to the influences of climate change.