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<br />3 <br />~ <br />~ <br />~ <br />~. <br />~ <br />... <br />~ <br />~ <br />~ <br />~ <br />~ <br />~ <br />., <br />., <br />., <br />~ <br />~ <br />4 <br />., <br />~ <br />~. <br />., <br />- <br />.. <br />.- <br />- <br />~ <br />.- <br />4 <br />4 <br />- <br /> <br />c) <br />c-) <br />.... <br />CO <br />-,1 <br />0:, <br /> <br /> <br />. <br /> <br />EXECUTIVE SUMMARY <br /> <br />Historical surveys of fish fauna have been conducted on most major tributaries of the <br />upper San Juan River (Smith 1976, Anderson et aI. 1993). Fish surveys that were <br />conducted prior to 1970 are rare, however during the 1970's fish surveys became much <br />more common and expanded into most drainages. <br /> <br />The objectives ofthis report were: I) to compile historical fish collection information for <br />the tributaries to the San Juan River downstream of Navajo Dam; 2) compile data <br />collected as part of this project during the years 1992 -1994; and 3) to compile, as <br />practicable, collections made upstream of Navajo reservoir during the study period 1992 - <br />1994. Many of the fish collections that have occurred since 1994 are included in this <br />report, however, these were not included as part of the original scope of work or <br />objectives for this project. <br /> <br />This study area included all major tributaries of the San Juan River that originate in <br />Colorado. The downstream boundary of tributaries within the study area was their point <br />of confluence with the San Juan River. The results of some surveys conducted on the <br />San Juan River upstream of Navajo Reservoir have also been provided. Tributaries of the <br />San Juan River that were represented in these results include; the Animas, Florida, La <br />Plata, Los Pinos, Mancos, Navajo, and Piedra rivers and Mc Elmo Creek. Also included <br />were several smaller creeks or streams that are tributaries of the larger rivers. The <br />smaller streams that were sampled consisted of Cherry Creek, Long Hollow Creek, Rock <br />Creek, Stollsteimer Creek, and Navajo Wash. <br /> <br />The data presented in this report are the result of two main sources of information. These <br />sources consist of: I) a literature review of historical fish surveys and, 2) data collected <br />by Miller Ecological Consultants (MEC) as part of a native fish habitat study (Miller et <br />aI. 1995). The literature review includes historical reports of fish surveys in the <br />previously mentioned tributaries of the San Juan River. <br /> <br />Historical studies of fish in tributaries of the San Juan River provide an account of native <br />and non-native species composition during a period of non-native introduction. The <br />Animas River has been the site of more historical fish surveys and earlier sampling <br />events than other tributaries. The earliest recorded sampling events (and other <br />unconfirmed early reports) in the Animas River included only records of native fish <br />species. By the 1950s, non-native fish had been detected in a reach of the Animas River <br />upstream of the Colorado border. Non-native species have persisted in the Animas River <br />since they were first reported; however, the composition and number of species have <br />changed. <br /> <br />Because there are few records of fish surveys in other tributaries prior to 1970, it is likely <br />that some non-native fish were already established in various tributaries before they were <br />reported. However, one of the earliest surveys from the La Plata River (1966) only <br />provided evidence of the existence of native fish. Although some non-native species had <br /> <br />Draft Final Tributary Report <br />Miller Ecological Consultants, Inc. <br /> <br />January 31, 2000 <br />Page i <br />