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SUMMARY <br /> This report examines the functional condition and ecological health of the Mancos River watershed, <br />Montezuma County, in southwestern Colorado. The Mancos River originates in the western flanks of the <br />La Plata Mountains, and flows south and west until it joins the San Juan River in northwestern New <br />Mexico. The river can be divided on the basis of hydrogeomorphology and ecology into five general <br />sections. First, the high elevation and high gradient reaches of the various tributaries that eventually <br />combine to form the main Mancos River, including the East, Middle and West Mancos Rivers, and <br />Chicken Creek. Second, the middle elevation reaches of the four main tributaries, which are lower <br />gradient and which run through canyons that incise the plateaus at the base of the peaks. Third, the section <br />of the river that flows through the Mancos Valley, which is relatively flat and used for irrigated <br />agriculture. Fourth, the reaches in Mancos Canyon, where the river runs in a deep canyon between several <br />large mesas, including Mesa Verde. And fifth, the lower section of the river from the mouth of Mancos <br />Canyon to the confluence with the San Juan River, where the river is low gradient and flows through flat <br />desert scrubland country. This report focuses primarily upon the reaches in the Mancos Valley (section 3), <br />since this is where there have been the most human impacts upon the stream/riparian system. Additional <br />surveys were taken for comparison upstream from Mancos Valley along the main tributaries (section 2), <br />and also downstream, in Mancos Canyon at the Mesa Verde National Park/Ute Mountain Ute Indian <br />Reservation border (section 4). Preliminary fieldwork and flyovers indicated that there have been <br />relatively few human impacts in the high elevation reaches of the upstream tributaries, and practical <br />considerations prevented the collection of data along the downstream reaches within the Ute Mountain <br />Ute Indian Reservation. <br /> The condition of each reach was measured using the protocol described in the User’s Guide for the <br />Rapid Assessment of the Functional Condition of Stream-Riparian Ecosystems in the American <br />Southwest(Stacey et al. 2006). This protocol examines five functional components of the stream-riparian <br />ecosystem that provide important benefits to humans and to aquatic and terrestrial wildlife: 1) non- <br />chemical water quality and indicators of nutrient pollution in the stream, 2) stream channel and flood <br />plain morphology, including the ability of the system to limit erosion and withstand flooding without <br />damage, 3) the presence of habitat for native fish and other aquatic species, 4) riparian vegetation <br />structure and composition, including the occurrence and dominance of non-native species, and 5) <br />suitability of the riparian zone as habitat for terrestrial wildlife, including threatened or endangered <br />species. Within each category, the RSRA evaluates between two and seven variables that reflect the <br />overall functional condition and health of the stream-riparian ecosystem. Quantitative measurements <br />made in the field are used to assign scores to each variable, ranging from “1” (completely non- <br />functional); to “5” (what would be expected to be found in a system that is completely functional and that <br />has not impacted by prior human activities). Mean scores are then calculated for each functional category, <br />and for all categories combined, to measure the overall condition of that particular reach. The goal of this <br />project was therefore to determine at each survey location which components of the ecosystem were <br />functioning either well or poorly at the present time, when compared to what would be found in an <br />unimpacted system of similar ecological and geomorphological characteristics. This information can be <br />used as a guide to determine whether restoration programs might be needed to help improve the health of <br />the river, as well as reaches where further action might not be necessary, depending upon the needs of the <br />local community. The surveys also serve as a baseline description that can be used to objectively monitor <br />the impact of any restoration program and/or change in land management practices that are undertaken on <br />that particular reach or section of the river. <br /> The Mancos River watershed has been occupied by Native Americans for many thousands of years, <br />and there has been extensive development and modification of the river for irrigated agriculture in the <br />3 <br />