watervulnerability

Coconino National Forest Watershed Vulnerability Assessment, Southwest Region (R3)
• Springs and headwaters are now important to natives due to the presence of invasives
downstream. These habitats may be further restricted, resulting in reduced populations or loss of
species.
• Decrease in perennial stream habitat is likely.
• Increased water temperatures are likely; in habitat with poor cover, temperatures could approach
tolerance limits.
• Reduced connectivity due to reduction in perennial (and seasonal) habitat.
• Increase in flows in the fall could trigger spawning and might result in less overwinter survival.
• Higher water temperatures result in lower O2 and higher primary productivity.
Water Uses
• Runoff will come earlier and baseflow will decrease during critical, dryer periods.
• Less flow during periods of current diversion.
• Warmer temperatures result in higher evaporative loss from reservoirs.
Riparian and Stream Habitats
• Year-round utilization of riparian vegetation by ungulates in Upper Clear and Upper West Clear
Creek. This has led to impacts to aspen and other tree species in other areas.
• Lower water tables will shrink the riparian areas longitudinally and by width.
• Conversion of interrupted perennial streams to intermittent is likely.
• Conversion of intermittent riparian areas to ephemeral or non-riparian areas is likely.
• Reduced water quality from loss of buffer.
• Changes to energy input (allochthunous).
• There may be some shift in ephemerals from spring to fall.
• Likely that fall flows will be flashier, resulting in poorer water quality.
• Perennials streams are likely to shrink.
Infrastructure
• Higher-intensity storms expected; peak flows will increase.
• More peaks may occur later in spring.
The key hydrologic process potentially affected by climate change on the CNF is the amount and timing
of precipitation. Aquatic and riparian habitats on the CNF are not abundant, and in many cases are already
stressed. If precipitation were reduced, or flow regimes adversely affected by timing or increased
temperatures, loss of the habitats would be expected.
Secondary effects are likely to further stress aquatic systems. Evapotranspiration will likely increase as a
result of increased seasonal temperatures and longer growing seasons. Flow regimes are likely to be
further impacted, as a result.
STEP 3 - Consideration of Watershed Sensitivity and Watershed Condition
The current condition of the watersheds is important because it will affect how each watershed responds
to changes in hydrologic processes. In this step, the existing condition of watersheds within the
assessment area was categorized in terms of current condition and natural sensitivity to potential change.
The assumption driving this analysis is that watersheds in good condition are more resilient than
watersheds in poor condition. It is also assumed that resilient watersheds will respond better (change less
in terms of outputs and ability to support resources) than watersheds that lack resiliency.
146 Assessing the Vulnerability of Watersheds to Climate Change