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<br />San Juan Tributaries upstream of Navajo Reservoir
<br />
<br />Los Pinos River, The Los Pinos was sampled on eight occasions during the 1970s, Site
<br />locations ranged from highway 160 down to Navajo Reservoir. Fish collections included
<br />native fish (bluehead sucker, flannelmouth sucker, mottled sculpin, and speckled dace)
<br />and non-native fish (white sucker, rainbow trout, and brown trout), The white sucker was
<br />the least common of all species collected in the Los Pinos during the 1970s, Only three
<br />specimens were collected during eight sampling occasions, Species that were most
<br />consistently captured during this time period include the mottled sculpin, speckled dace,
<br />and brown trout.
<br />
<br />Navajo River, The Navajo River was sampled on nine occasions between 1970 and
<br />1979, Site locations ranged from Juanita, Colorado (near the confluence with the San
<br />Juan River) upstream to Chromo, Colorado (near the Navajo River headwaters), Results
<br />of sampling efforts indicated the presence of five native fish (roundtail chub, bluehead
<br />sucker, flannelmouth sucker, mottled sculpin, and speckled dace), and five non-native
<br />fish (white sucker, rainbow trout, fathead minnow, brown trout, and brook trout), Most
<br />consistently present in fish collections was the mottled sculpin and speckled dace,
<br />Roundtail chubs were only collected at the location near Juanita, Colorado, The white
<br />sucker was the most consistently occurring non-native species, Only one specimen of
<br />common carp was collected during this time period,
<br />
<br />Piedra River, The Piedra River was only sampled on two occasions during the 1970s,
<br />Native fish that were represented in collections included; bluehead sucker, mottled
<br />sculpin and speckled dace, Non-native fish collected in the Piedra included the white
<br />sucker, cutthroat trout, rainbow trout and brown trout. Flannelmouth suckers were not
<br />present during these collection events in the Piedra River.
<br />
<br />General trends in fish collections during 1970 - 1979 indicated that native fish generally
<br />dominate the collections, but several non-native fish species had become established in
<br />tributaries of the San Juan River. The white sucker was most common in the tributaries
<br />upstream of Navajo Reservoir. Mottled sculpin and trout species were more abundant at
<br />higher elevations, while other fish species seemed to prefer the mid to lower stream
<br />reaches, Roundtail chub were collected in the La Plata, Mancos, and Navajo River
<br />systems, White sucker were collected in the Los Pinos, Navajo, and Piedra River
<br />systems, Table 7 provides a summary of fish abundance estimates in tributaries upstream
<br />of Navajo Reservoir. The San Juan River upstream of Navajo Reservoir was not sampled
<br />during the 1 970s,
<br />
<br />Draft Final Tributary Report
<br />Miller EcoJogical Consultants, Jnc,
<br />
<br />January 31, 2000
<br />Page 13
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