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<br />-" <br /> <br />1) Identify critical water-dependent species and systems: In order to understand environmental <br />water demands on a river-specific basis, SWSI should develop an understanding of the key <br />species and systems that depend on those rivers~ Several sources of information on the <br />location of key water-dependent species and systems are available to the SWSI. The Nature <br />Conservancy would be willing to assist in collecting relevant data and recommends several <br />key sources that would help to inform the SWSI project: <br />· Colorado Division of Wildlife (CDOW): The CDOW has compiled detailed information <br />on the location of water-dependent species and has conducted site-specific investigations <br />for development of instream flow and lake level appropriations. <br />· Colorado Natural Heritage Program (CNHP): The Colorado Natural Heritage Program <br />has identified the geographic locations of species and communities and has developed <br />estimates of the primary areas that support the continued survival of those targeted <br />species and communities. <br />· Colorado Water Trust: The Colorado Water Trust has developed maps that depict stream <br />and river priorities and critical flow reaches, as identified by a variety of non-profits and <br />state and federal agencies engaged in protection of aquatic resources. <br />· TNC Ecoregional Plans: Through its science-based ecoregional planning process, The <br />Nature Conservancy, along with state a11d federal partners has identified ecologically- <br />important areas throughout Colorado. <br />· Upper Colorado River Endangered Fish Recovery Program: This successful, multi- <br />stakeholder program has characterized flow needs for endangered fish in several west <br />slope basins, including the Green, Yampa, Colorado, and Gunnison. <br /> <br />2) Assess Environmental Demand: After identifying the location of key aquatic species and <br />riparian communities, the next step is to establish the enviromnental or instream needs of <br />these communities. Several models for identifying environmental demands have been <br />implemented successfully in Colorado~ For example, the Upper Colorado River Endangered <br />Fish Program has identified and protected variable base and peak flows on several large west <br />slope rivers to support endangered fish recovery (see Muth et a12000). An assessment of <br />enviromnental demand would include identification of the key components of the flow <br />regime that support aquatic or riparian communities, including base flows, normal high <br />flows, drought and flood conditions, and interannual variability in each of these elements. <br />While techniques for determining enviromnental flow needs on a case-by-case basis are still <br />evolving and may require a 111eaming by doing" approach (poff et al. 2003), the leading <br />model involves assembling experts to evaluate flow needs, Aquatic and riparian ecologists <br />and fluvial geomorphologists would work alongside hydrologists to identify key species or <br />ecosystem processes that are flow-dependent, and then to quantify the relationship of those <br />species or processes to specific flows~ The resulting enviromnental flow prescription would <br />not be a rigid, perpetual regime, but would be modified based on observed system responses <br />to ensure that environmental objectives are met. <br /> <br />Proposal for SWSI: <br />The Nature Conservancy acknowledges the challenge of producing a detailed assessment of <br />environmental demand on a statewide basis in a one year recolUlaissance study such as the <br />SWSI. TNC would propose several alternative approaches to quantifying enviromnental <br />demand: a) a coarse statewide characterization; b) a select set of pilot projects (2-5) at critical <br />