watervulnerability

Shasta Trinity National Forest Watershed Vulnerability Assessment, Pacific Southwest Region (R5)
BACKGROUND
Eleven National Forests across the country participated in a pilot study evaluating potential impacts of
climate-induced hydrologic change on local water resources. Each forest identified its specific water
resource values at risk, assessed the associated watershed sensitivities, and then considered expected
effects from future climate change exposure to evaluate the relative vulnerabilities of forest watersheds to
climatic change. This report summarizes the results from the Shasta Trinity National Forest, representing
California and the Pacific South West Region.
A primary objective of these assessments is to assist forests in developing strategies to guide forest
management in response to climate change and promote sound resource investments. Determining areas
that are most vulnerable to climate change impacts would help focus on the adaptation opportunities that
may exist within these areas. Knowing what is at risk and how it may be affected presents the opportunity
to incorporate watershed vulnerability into future management actions. Promoting resiliency in areas that
are susceptible to hydrologic change is proposed as the appropriate management strategy.
Water supplies, aquatic habitat, and the stability of forest infrastructure are all subject to significant
changes as a result of climate change. More severe droughts, more frequent and larger floods, lower
seasonal stream flows, higher peak flows, increasing water temperatures, increasing erosion and
sedimentation are just a few of the changes that are likely to occur as a result of climate change,
especially in the western United States. This vulnerability assessment evaluates the relative risk of impact
from climate change to aquatic resources and infrastructure on the Shasta Trinity National Forest.
Figure 1. Location of Shasta-
Trinity NF, and river basin and
climatic sections
The Shasta Trinity National Forest manages 2.1 million acres of public land located in Northern
California (Figure 1) with forest headquarters located in Redding California. The Forest is in the Pacific
Southwest Region (R5) of the USFS. Mediterranean climate of northern California is characterized by hot
dry summers and cool wet winters. All climate zones in the continental United States receive precipitation
in the summer except California.
186 Assessing the Vulnerability of Watersheds to Climate Change