watervulnerability

Coconino National Forest Watershed Vulnerability Assessment, Southwest Region (R3)
relative assessment of risk for recreation facilities. Results of the infrastructure rating (with the location of
campgrounds within 300 ft of channels) are shown in Figure 6.
Water Uses
Water from the forest supports domestic, livestock, wildlife and fish, recreational, and agricultural uses
downstream, and all watersheds within the analysis area are highly valued for this reason. Additionally,
water for domestic use is captured by and delivered from the C.C. Cragen Reservoir. Substantial surface
water is stored close to its source in stockponds or tanks, where it used for stock water and wildlife
purposes. Numerous agricultural diversions exist on the lower reaches of Oak, Beaver, and West Clear
Creeks and the Verde River.
Ratings of relative subwatershed values for water uses were based on a combination of all these factors.
The amount of water (acre ft) diverted in each watershed was determined, and subwatersheds with no
diversions were given a low value, watersheds with less than 500 acre ft diverted (annually) were classed
as moderate, and those with greater than 500 acre ft were rated as high. GIS was used to obtain a count of
tanks per subwatershed. Subwatersheds were divided into three classes: those subwatersheds with 16 or
fewer tanks were given the lowest value, those with 17 to 32 had moderate value, and those with more
than 32 received the highest rating. Tanks and diversions were given equal weight, and were combined to
produce a single water resource score. These values were then divided into thirds, with the highest third
of subwatersheds given a rating of “high.” Finally, all subwatersheds that contribute flow to the C.C.
Cragen reservoir were rated as high. The results of the water-uses rating are displayed in Figure 7.
Riparian and Spring Habitats
Relative to other areas of the country, the amount of aquatic and riparian habitat (including springs) on
the CNF is limited. Riparian areas represent 0.7% of the area on the Forest. These spatially limited areas
provide habitat for 80% of the Forest’s bird species, including neotropical species. Eighty percent of the
Forest’s vertebrate species depend on riparian habitat for at least half of their life cycles. These habitats
are vitally important as habitat for numerous reptiles and amphibians not listed above and other aquatic
organisms, such as macroinvertebrates. Springs also provide habitat for aquatic and riparian species,
including numerous endemic macroinvertebrate species.
The relative value of subwatersheds for this resource was based on two data sources: miles of riparian
habitat and the number of springs. GIS was used to determine the miles of riparian habitat in each
subwatershed. As with other attributes, values for each watershed were ranked and then grouped into
thirds, with subwatersheds with the most riparian habitat (>17 miles) given the highest scores. Forest GIS
data for springs were used to determine the number of springs per watershed; these were then grouped
into thirds. A riparian-spring rating was obtained by combining the subwatershed scores for the individual
factors, with the riparian value given twice as much weight as the spring rating. To be clear, ratings of
“high” were given a score of 3, and low ratings were given a score of 2. The combined scores were then
ranked and divided into thirds, with the highest third rated as high value.
138 Assessing the Vulnerability of Watersheds to Climate Change