2012-03-07_PERMIT FILE - C2010088 (19)

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water habitat. None of the designated cutthroat trout waters is directly tributary to the Reed Wash watershed, which would preclude immigration into the system during periods of high water flows. However, the 100 -year floodplain habitat remains protected critical habitat for the four Colorado River fishes, excluding the greenback cutthroat. No critical habitat rules have been published for the greenback cutthroat trout (USFWS 2010b). For the Colorado River fishes, critical habitat is defined as all areas within the 100 -year flood plain that provide the following three characteristics: • A sufficient quality and quantity of water needed by the fish at each life stage. • Physical characteristics such as side channels, backwaters, floodplains and bottomlands, which are used by the fish as spawning, nursery, feeding and rearing sites. • An adequate food supply and other biological characteristics. 4.0 IMPACT ASSESSMENT 4.1 MAMMALS 4.1.1 Mule Deer: Since mule deer densities are low in the area, affects to the local population are likely to be minimal. Approximately one -third of the habitat affected by the new rail spur will be constructed in a land farm that is a bio- treatment area for waste material from the old refinery and supports very limited vegetation. The remaining portion of the spur will be constructed through habitat that provides cover for mule deer but low forage value due to the lack of palatable plant species. The rail spur is located adjacent to fragmented habitat on all sides, which decrease the suitability for consistent use by mule deer. Concentrating new disturbance that is adjacent to existing facilities reduces the effects of the development on mule deer. The Reed Wash riparian corridor will remain intact and the project is not designed to affect this area. This will allow for a corridor and protective cover for mule deer potentially occupying the project area. 4.1.2 Predatory Mammals 4.1.2.1 River Otter: Based on the results of the biological survey, otter could potentially occupy habitat throughout Reed Wash in the project area (Figure 3). It is generally known, that disturbances of human origin can have adverse effects on otter populations (Boyer et al. 1994, Dean et al. 2002). However, most studies dealing with habitat selection by otters have been conducted in regions with low levels of disturbances; therefore, there is a lack of information on how otter are affected by human disturbance factors. The results of one study conducted in Canada (Gallant 2009), indicates that otters responded mostly to the presence of habitat features they use and secondarily to the presence of man -made structures or activities in an area. It is suspected, that if the existing or improved habitat in Reed Wash remains intact, river otter would not likely be affected by the construction of the rail spur. The otter currently using Reed Wash likely traveled to and from the site by crossing under I -70 and probably encountered disturbance by vehicular traffic. In addition, the site where the otter 20