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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EXECUTIVE SUMMARY

Historical surveys of fish fauna have been conducted on most major tributaries of the
upper San Juan River (Smith 1976, Anderson et al. 1993), Fish surveys that were
conducted prior to 1970 are rare, however during the 1970's fish surveys became much
more common and expanded into most drainages.

The objectives of this report were: I) to compile historical fish collection information for
the tributaries to the San Juan River downstream of Navajo Dam; 2) compile data
collected as part of this project during the years 1992 - 1994; and 3) to compile, as
practicable, collections made upstream of Navajo reservoir during the study period 1992 -
1994. Many of the fish collections that have occurred since 1994 are included in this
report, however, these were not included as part of the original scope of work or
objectives for this project.

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This study area included all major tributaries of the San Juan River that originate in
Colorado. The downstream boundary of tributaries within the study area was their point
of confluence with the San Juan River. The results of some surveys conducted on the
San luan River upstream of Navajo Reservoir have also been provided. Tributaries of the
San Juan River that were represented in these results include: the Animas, Florida, La
Plata, Los Pinos, Mancos, Navajo, and Piedra rivers and Mc Elmo Creek. Also included
were several smaller creeks or streams that are tributaries ofthe larger rivers, The
smaller streanlS that were sampled consisted of Cherry Creek, Long Hollow Creek, Rock
Creek, Stol/steimer Creek, and Navajo Wash,

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The data presented in this report are the result of two main sources of information. These
sources consist of: 1) a literature review of historical fish surveys and, 2) data collected
by Miller Ecological Consultants (MEC) as part of a native fish habitat study (Miller et
al. (995), The literature review includes historical reports of fish surveys in the
previously mentioned tributaries of the San Juan River.

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Historical studies of fish in tributaries of the San Juan River provide an account of native
and non-native species composition during a period of non-native introduction, The
Animas River has been the site of more historical fish surveys and earlier sampling
events than other tributaries. The earliest recorded sampling events (and other
unconfirmed early reports) in the Animas River included only records of native fish
species. By the 1950s, non-native fish had been detected in a reach of the Animas River
upstream of the Colorado border. Non-native species have persisted in the Animas River
since they were first reported: however, the composition and number of species have
changed,

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Because there are few records of fish surveys in other tributaries prior to 1970, it is likely
that some non-native fish were already established in various tributaries before they were
reported, However, one of the earliest surveys from the La Plata River (1966) only
provided evidence of the existence of native fish, Although some non-native species had

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Draft Final Tributary Report
Miller Ecological Consultants, Inc.

January 31, 2000
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