watervulnerability

Grand Mesa, Uncompahgre and Gunnison National Forest Watershed Vulnerability Assessment, Rocky
Mountain Region (R2)
Figure 22. Runoff Sensitivity Ranking
Past Management Activity Stressors
Data used to evaluate past management or activity stressors were taken from the watershed assessment
conducted for the Forest plan revision. (Additional discussion of the data uses, limitations of that data,
and the effects of these anthropogenic stressors can be found in the Chapter 5, Section C of the watershed
assessment completed for the Forest plan revision (2005).) A mix of long-term effects (e.g., dams and
major roads) and short-term effects (e.g., timber harvests) have been included. Some stressors have direct
effects on or near channels; others affect areas throughout a subwatershed. Several individual stressors
were combined so that effects were not overweighed in the final subwatershed rankings. Data used for
this evaluation were limited to areas within the GMUG boundary. For watersheds that have a large
portion of off-Forest area, these rankings may need to be adjusted as off-Forest data become available.
Individual activity stressors considered include those listed below.
Flow Related Stressors
1. Stream miles below diversions, expressed as a percentage of perennial and intermittent stream
network in a watershed. There are some significant caps in understanding of the specific effects
of diversions on aquatic systems. Operation information is only available for the major diversion,
concerning timing and quantity of water diverted from or into the natural stream network
2. Stream miles below reservoirs, expressed as a percentage of perennial and intermittent stream
network in a watershed. Only reservoirs of 50 surface acres or larger were included. There are
many smaller reservoirs and stockponds whose effects are not addressed; however, it was felt that
these smaller reservoirs would have limited ability to influence flow regimes. Operation of larger
reservoirs can regulate flows in ways that benefit fisheries and other aquatic values.
95 Assessing the Vulnerability of Watersheds to Climate Change