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<br />24 <br /> <br />Water Quality <br /> <br />Baseline conditions describing water quality in the San Juan River were <br />described in the Service's January 12, 1995, biological opinion for the Navajo <br />Indian Irrigation Project. Information on existing water quality in the San <br />Juan River has been derived from data gathered by the Department of the <br />Interior as part of its National Irrigation Water Quality Program <br />investigation of the San Juan River area in northeastern New Mexico (Blanchard <br />et al. 1993) and results from Reclamation's water quality data for the <br />Animas-la Plata project. While a fair amount of data has been collected, the <br />selenium data collected to date may not be conclusive. <br /> <br />Concentrations of selenium in water samples collected from the mainstem of the <br />San Juan River exhibit a general increase in concentration levels with <br />distance downstream from Archuleta, New Mexico, to near Bluff, Utah, (<1 ~g/l <br />to 4 ~g/l). Tributaries to the San Juan carry higher concentrations of <br />selenium than found in the mainstem river immediately upstream from their <br />confluence with the San Juan; although these levels are diluted by the flow of <br />the San Juan, the net effect is a gradual accumulation of the element in the <br />river's flow as it travels downstream. Increased selenium concentrations may <br />also result from the introduction of ground water to the mainstem of the river <br />along its course. Recent data (1989 -94) collected by Reclamation show mean <br />selenium levels in water samples from the Animas River at the Durango pumping <br />plant site are 5.7 ~g/l, with a maximum level of 28 ~g/l. Data collected from <br />March to October 1993 showed average selenium levels of 6.4 ~g/l at the <br />pumping plant site, with levels increasing downstream to 13.6 ~g/l at Aztec, <br />New Mexico. Questions have been raised regarding the high values in <br />Reclamation's selenium data from the Animas River. Reclamation is in the <br />process of investigating the validity of this data and continues to collect <br />samples from the Animas River. <br /> <br />Sediments and biota associated with the San Juan River also showed elevated <br />selenium levels. Composite fish samples were collected during the Department <br />of the Interior study from six reaches of the San Juan River in spring 1990 <br />and from seven reaches in fall 1990. Each composite sample typically <br />consisted of five individuals of a single species. Composite samples of <br />common carp (CvDrinus carDio) and flannelmouth sucker (Catostomus latiDinnis) <br />were collected from each reach during each sampling period. In addition, <br />six channel catfish (Ictalurus Dunctatus) composite samples were collected <br />during the two sampling periods in reaches where the species was encountered. <br />The highest concentrations of selenium in common carp and flannelmouth sucker <br />occurred in the river from Bloomfield to Farmington, New Mexico (Blanchard <br />et al. 1993). <br /> <br />The other contaminants of concern are polycyclic aromatic hydrocarbons (PAHs), <br />also known as polynuclear aromatic hydrocarbons (PNAs). The PAH compounds may <br />reach aquatic environments in domestic and industrial sewage effluents, in <br />surface runoff from land, from deposition of airborne particulates, and <br />particularly from spillage of petroleum and petroleum products into water <br />bodies (Eisler 1987). The PAHs were the first compounds known to be <br />associated with carcinogenesis (Lee and Grant 1981). Several PAHs are among <br />the most potent carcinogens known to exist, producing tumors in some organisms <br />