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3.1 III. AFFECTED ENVIRONMENT 3.1 Introduction Affected environment describes the current conditions of the area to be affected by the implementation of the alternatives. This chapter describes the general physical and biological conditions existing in the study area, including hydrology, aquatic biology, wildlife biology, and recreational use. Figure 3.1 presents a generalized map of the study area. In addition, two federally endangered birds, bald eagle, and peregrine falcon, are included since these populations tend to congregate around small- to medium-sized lakes and next to rivers during the winter. Four species of fish listed as threatened or endangered by the Fish and Wildlife Service or the State of Colorado are also discussed. 3.2 Hydrology An operational model for Ruedi Reservoir was developed to simulate reservoir and streamflow conditions that result from various operational schemes and levels of water sales. Results of the simulation were used in evaluating alternatives and in selecting a preferred operational alternative. The operational model for Ruedi Reservoir is based on historic operations of the reservoir, administration of Colorado water rights, Fryingpan-Arkansas Project Operating Principles, the authorizing legislation, and the terms and conditions of the proposed water service contracts. A detailed description of model inputs and outputs was prepared and released in February 1988 (U.S. Department of the Interior, Bureau of Reclamation, 1988). The primary source of streamflow in the upper Colorado River basin is the spring melting of the accumulated winter snowpack. The annual hydrograph (the discharge over time) of rivers in the study area shows the highest streamflows occurring during the late spring and early summer months. Streamflow is at its lowest during the winter months. Streamflows in the Fryingpan River are stored in Ruedi Reservoir during the peak runoff period, then released later in the year for use in downstream reaches of the Fryingpan, Roaring Fork, and Colorado Rivers. Streamflows in the Roaring Fork River are affected by diversions which transport water out of the basin to the Arkansas River via the Fryi ngpan -Arkansas Project. In addition, numerous other storage and transmountain water diversion projects modify the streamflows of the Colorado River.