watervulnerability

Chugach National Forest Watershed Vulnerability Assessment, Alaska Region (R10)
avalanches, and exposure of glacial moraines could lead to higher bedload transport and channel shifts in
depositional areas. This deposition, however, is seen as a natural response and does not pose risks to
infrastructure or other values. Some forms of fish habitat enhancement that might be considered for
mitigation, such as instream structures, may not be appropriate due to the potential channel instability.
Managers also need to review existing restoration plans, road maintenance plans, and other work that
already has been identified. Mitigation measures for the increased risk of fire in the Resurrection Creek
watershed are already spelled out in the All Lands/All Hands program developed with other agencies and
the Kenai Peninsula Borough. Fuel reduction goals, public education, and emergency preparedness
measures are already lined out and are being implemented. Other entities, such as the Copper River
Watershed Project in the Cordova area, have ongoing restoration programs, including the Million Dollar
Eyak Lake project. Thus, Forest Service managers may have many opportunities for collaborative work.
The greatest issue, however, may be the uncertainty as to how fish and wildlife species may respond to
the effects of climate change. Salmon, in particular, are a key part of the ecosystem and the economy in
Alaska. Unlike areas in the lower 48 states, coastal streams will have more, not less, water, and water
temperatures will not rise enough for lethal effects to salmonids. Direct mortality is unlikely, but
increased water temperatures could disrupt seasonal timing and life history cycles of both the fish and the
food chains upon which they depend. If, for example, warmer water temperatures cause salmon eggs to
mature more quickly, the fry could hatch too early in the season when no prey is available – unless the
maturation of zooplankton and other organisms is temperature-dependent and increases as well. Without
this basic knowledge, it is difficult to determine how the resources will be affected.
There are a number of other biological questions, particularly whether species have the genetic/behavioral
plasticity to adapt to changes. As an example, most salmon can have a wide range of spawning times,
habitats, and life-history patterns. If eggs develop more quickly with warmer water, perhaps latespawning
stocks will preserve the species. Perhaps the best mitigation is for land managers to maintain or
restore diverse habitats and the genetic stocks that use them (something managers should be doing
anyway). This is not to say populations will not be stressed, and population managers may well need to
reduce harvests or take other actions as species adjust.
To answer some of the biological questions, researchers from the Pacific Northwest Research Station and
a number of universities are conducting studies in the Cordova area. Two current studies involve looking
at differences in salmon and aquatic invertebrate life histories and timing, based on different temperature
conditions across the Copper River Delta, including some sites in the Eyak Lake watershed. In these
cases, physical locations are being used as a surrogate for the temperature changes that are predicted from
climate change. Additional baseline data is also being collected on surface and groundwater temperatures,
another major data gap.
In summary, extensive climate data resources are available through the University of Alaska, Fairbanks,
but limited historic data and models may hinder quantitative assessments. However, determining climate
change trends, identifying resource values, and analyzing how those resources might be affected may be a
sufficient start for determining future actions. In Alaska, where most areas are relatively pristine, it made
more sense to focus on more developed watersheds to identify specific issues and actions.
Much of the mitigation efforts that need to be done are actions that may already be planned or should be
the normal plan of work. Stream projects that restore natural flows and functions may be the best way to
protect fish habitat and reduce the risks of floods. Most Forests have conducted watershed assessments,
road condition surveys, and fire management plans. The standards may need to be reviewed in light of
predicted changes, such as increasing cross drainage or culvert sizes for roads, but most of the problems
may already be identified. Lastly, a number of other government entities, agencies, community groups,
268 Assessing the Vulnerability of Watersheds to Climate Change