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I I I I I I I I I I I I I I I I I I I ES ENGINEERING.SCIENCE and Turkey Creeks upstream of the existing reservoir are riparian areas. An illustration of the riparian zone concept is shown in Figure 1. WETLAND CHARACIERISTlCS Ecological characteristics of jurisdictional wetlands and of riparian areas likely to be inundated by water storage scenarios are described in the this section. Although all the wetland and riparian areas associated with Bear and Turkey Creeks were eYlImined, those areas within the zone of potential mllYimum inundation were investigated most intensively. The inundation zone included areas between elevations of 5,558 and 5,585 feet above mean sea level (AMSL). Wetland and riparian characteristics in the potentially inundated areas are representative of these resources occurring outside the innn<lation area. Botanical and physical characteristics of each type of area are described. The general spatial distribution of wetlands, total wetland acreage, general overall quality, and primary environmental functions and values provided by these wetlands are summarized. Botanical Features The most abundant wetland types consist of associations of trees and shrubs, dominated by two cottonwood species [narrowleaf cottonwood (l>>opulus anlPL~tifolia.) and plains cottonwood (rQpulus SaI:l1entiO] and two willow species [sandbar willow (Sa!i3 exiiUa) and peachleaf willow (sm amYlldaloides)]. These species. occur as both homogeneous and well-mixed stands. Areas composed .primarily of dense willow stands are commonly referred to as willow shrub or willow thicket wetlands. Stands of this type are commonly found along the current reservoir shoreline, the alluvial fans at the mouths of both Bear and Turkey Creeks, and scattered throughout the floodplains of both creeks. Areas composed primarily of saplings and mature trees of plains and narrowleaf cottonwoods are commonly referred to as forested wetlands if the shrub and ground cover plant species are strongly affiliated with moist to wet soils. Such species include sandbar willow, sedges (r-arex spp.), rushes (Juncus spp.), and spikerushes (pleocharis spp.). If the shrub and ground cover plant species are typical of on wetland plant communities, the forested areas are considered either a riparian or upland type (depending on plant composition of the specific site). The willow shrub and cottonwood forested types intermix in varying proportions throughout both creek floodplains. The intermixed types are frequently referred to as cottonwood- willow wetlands. Narrow wetland corridors composed primarily of willows, cattails (T~ha an~tifolia), sedges, and rushes occur along two unnamed and intermittent-flow drainages that enter the reservoir from the north. Corridor widths vary from 15 to 25 feet. Vegetation is very dense. Some sections of both wetland corridors contain young saplings of plains cottc:Jwood. There are several small standing-water areas within several wetland units of the Turkey Creek floodplain that enhance wetland habitat quality for waterfowl, songbirds, and other wildlife. These ponds appear to be sustained by a shallow -3- Ol&-3-]