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on~520 EXECUTNE SUMMARY The San Juan River Seven Year Research Plan included among its goals a long-teon water-quality program, the first step of which was a water quality and contaminants review. The review was intended to synthesize existing water quality and contaminants infoonation on the San Juan River and its tributaries in order to identifY future research needs. This report constitutes the first portion of the review, the compilation of existing infoonation for the New Mexico, Colorado, and Utah portions of the San Juan River basin. All studies, reviews, unpublished data sets, and communications that were available by I July 1993 were included. Over 85 individuals from more than 25 agencies and organizations were consulted in the research process. The San Juan River from Navajo Reservoir to the confluence of the Mancos River, and the Animas and La Plata Rivers, have been investigated fairly extensively for the presence of contaminants. Reaches or lakes where little contaminants research has been conducted included the San Juan River above Navajo Reservoir; the Navajo River; the Piedra River; Navajo Reservoir; Los Pinos River; the Florida River; Chinde Wash; the San Juan River from Cottonwood Wash to Mexican Hat; Cottonwood Wash; Chinle Creek; and the San Juan River from Mexican Hat to the San Juan ann of Lake Powell. Major sources of contaminants identified in the basin were irrigation and mineral extraction, processing, and use. Irrigation projects sponsored by the Department of the Interior have been thoroughly studied through reconnaissance investigations aimed at determining the extent of toxic irrigation return flows; unfortunately, only one of three reconnaissance investigations was available for inclusion in the review. Irrigation return flows that would be generated by the proposed Animas-La Plata Project have also been examined. Seleniwn is the major contaminant associated with irrigation return flows, and it has been suggested that flows may also serve to transport other contaminants such as pesticides and polycyclic aromatic hydrocarbons (PAHs). Mineral extraction, processing, and use were abundant and widespread activities in the basin. Oil, natural gas, and coal operations dominated, while the mining and milling of uraniwn and other metals have been historically important. None of the activities has been investigated to the extent necessary to determine their effects on basin water quality or fish health. Contaminants of the greatest concern associated with these activities are P AHs, seleniwn, and certain metals. Sources of seleniwn have been widely investigated, but effects of seleniwn on rare basin fish are unknown. There was minimal information on either the sources or effects of P AHs. The presence of disease in fish was highly correlated with contamination, but a small amount of disease data has been collected from only the San Juan and Animas rivers. In general, there exists a surplus of abiotic data identifying potential contaminants and a dearth of biotic data linking those contaminants to fish health. Future research efforts by federal and state government agencies should be coordinated so that information generated on contaminants, sources, and effects can be connected to make management recommendations. The determination of toxicities of various contaminants to fish species is cmcial, but management recommendations cannot be made without first identifying contaminants sources. Because resources are limited, priorities for research should be established before further investigations are begun. xv