C150094 Addendum to Biological Assesment for Long Hollow

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Addendum to Biological Assessment for the Proposed Long Hollow Reservoir approximately RM 174 on the San Juan River (i.e., distance upstream from Piute Farms, near or within Lake Powell) (see Figure 16). The upstream most distribution of Colorado pikeminnow in the San Juan River is the Hogback Diversion at RM 158.6. Hence, the distance from the proposed Long Hollow reservoir to presently occupied habitat of Colorado pikeminnow is about 60 miles of the La Plata River. Life Requisites The Colorado pikeminnow is the largest of all North American cyprinid fishes (minnows) with the capabilities of reaching lengths of six feet and weigh over 80 pounds (Holden, 1995) although that rarely if ever happens currently because of numerous identified adverse environmental conditions. They can live for more than 50 years. Life history of the Colorado pikeminnow was summarized by Tyus (1991). The Colorado pikeminnow evolved within the Colorado River Basin and adapted to rivers exhibiting a wide range of flows and water quality conditions. Prior to the introduction of non- native pisciverous fishes, the pikeminnow was the primary fish eating fish in the Colorado River system, preying on other native fish species. The pikeminnow uses a variety of habitats tied to different life stages and requires a relatively long segment of river in order to successfully complete its life cycle. Adult pikeminnow have been known to migrate in excess of 50 miles to spawn, which is typically in upstream reaches of their occupied habitats. The primary strategies being used to recover this fish species are to maintain more natural river flow patterns by releasing more water from dams in the spring, stabilize flows in late summer for young fish, ensure that stocking of non-native fish does not conflict with endangered fish recovery and build passageways and "ladders" around certain dams and barriers to allow endangered fish to migrate up and down the river. One of the requisites for removing the Colorado pikeminnow from the list of T&E species is when "all management actions identified in the Recovery Goals are implemented and achieved, 991-077.080 Wright Water Engineers, Inc. Page 5 November 2003