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32 food sources. Utilization of these types of habitats is thought to be very important to preparing adult Colorado squawfish for spawning which generally occurs from mid-July through August. The quality and availability of flooded backwater habitats are diminished with reductions in spring runoff. Further flow reduction in the 15-mile reach during July, August, and September are of concern. During most years the Wolford Mountain Project would cause small flow accretions in the IS-mile reach during late summer months. However. there is no.guarantee under State water law. that these small flow accretions would not be diverted before the IS-mile reach. Water Qualitv The Project's depletion would cause a proportionate decrease in dilution which in turn would cause a proportionate increase in heavy metal. selenium. salts, PAHs. pesticides, and other contaminant concentrations in the Colorado River. An increase in contaminant concentrations in the river would likely result in an increase in the bioaccumulation of these contaminants in the food chain which could adversely affect the endangered fishes. particularly the predatory Colorado squawfish. Selenium is of particular concern due to its effects on fish reproduction and its tendency to concentrate in low velocity areas that are important habitats for Colorado squawfish and razorback suckers. The potential increases in selenium concentrations caused by the Project. although very small. represent increases when baseline levels are already near or above the threshold level of 2 fJg/L recommended by the Service. Phvsical Habitat High spring flows are very important for creating and maintaining complex channel geomorphology and suitable spawning substrates, creati,ng and providing access to off-channel habitats. and possibly stimulating Colorado squawfish spawning migrations. Adequate summer and winter flows are important for providing a sufficient quantity of preferred habitats for a duratiqn and at a frequency necessary to support all life stages of viable populations of all endangered fishes. To the extent that the Project will reduce flows, the ability of the river to provide these functions will be reduced. Biolooical Environment The modiflcation of flow regimes, water' temperatures, sediment levels. and other habitat conditions caused by water depletions has contributed to the establishment of nonnative fishes. To the extent that it would reduce flows