WSP07867

• File Number: 8240.300.31.J
• Description: San Juan River - Environmental Studies
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 2/1/2000
• Title: Ichthyofaunal Surveys of Tributaries of the San Juan River - NM
• Water Supply Pro - Doc Type: Report/Study

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River. Since 1972 this species has been collected (infrequently) from the La Plata River
and Mancos River. This species is usually restricted to the cooler temperatures at the
upper reaches of streams, The brook trout was represented during the] 994 habitat use
study by only two individuals. One juvenile individual was captured in riffle habitat, and
an adult was captured in pool habitat.

Salmo frulta (brown trout): Earliest reports of brown trout in tributaries of the San Juan
River came from collections made in the Animas River during] 954, The brown trout
was introduced to the La Plata River during 1958 and has maintained small populations
there since that time (Smith 1976), This non-native species was apparently established in
all major tributaries upstream of Navajo Reservoir prior to collections made during the
1970s, By the 1990s the brown trout was also common in collections from the Florida
River and La Plata River. Brown trout were not reported during historical sampling
efforts on the Mancos River or Mc Elmo Creek.

Brown trout were represented in the compiled habitat use data by all three age classes.
Only two YOY brown trout were encountered and both were collected from riffle habitat.
Juvenile and adult brown trout were mostly encountered in pool habitat, although they
were well represented in each available habitat type,

Cyprinella lutrensis (red shiner): The first reported collection of this non-native species
in the San Juan drainage came from sampling which occurred in the Animas River during
1954, The red shiner was collected from the Mancos River and Navajo Wash during
1975, and was reported from the La Plata River during 1976, The earliest collections
from Mc Elmo Creek occurred during 1978. Representative of this species have been
reported in the Mancos River and Mc Elmo Creek during every decade since they were
initially discovered. At some ofthe lower sites on the Mancos River this species was one
of the most abundant of the species collected during the 1994 habitat study, Most red
shiners and were found in glide habitat.

Cyprinus carpio (common carp): The common carp was apparently established by 196 I
in the area now inundated by Navajo Reservoir (Olson 1962a), The earliest fish surveys
to report this non-native species in tributaries of the San Juan River occurred during the
1970s, During this time the common carp was reported from three major tributaries: the
Animas River, Mancos River (and Navajo Wash), and Mc Elmo Creek. It has since been
collected from other tributaries upstream and downstream of Navajo Reservoir. These
tributaries include: the Navajo River, Piedra River, and Florida River. Since the 1970s
small populations of common carp have apparently become established at some locations
(most of these areas occurring on the Animas River). Sampling at these locations has
revealed that this species constitutes a relatively small numeric portion of the total
species composition. Low numbers of large individuals were typical in collections where
this species had become established. Common carp were only represented by a few
individuals in the juvenile and adults size class during the 1994 habitat study, Regardless
of size, common carp were only collected from glide habitat.

Draft Final Tributary Report
Miller Ecological Consultants, lne,

January 31, 2000
Page 23