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Evaluating the Impacts of Conservation Practices on Watershed Health in a Salmon-Bearing Rangeland Watersheds, Asotin Creek, Washington

Objective

Work with stakeholders to develop site-specific criteria of watershed health for the Asotin Creek watershed in Washington State. Suitability to enhance or maintain native salmonid fish runs will be a key component, as will ability to support desired human uses. <P>Synthesize existing data and models for Asotin Cr. and create geo-referenced history of this watershed since settlement, including past conservation projects aimed at the stream channel, water quality, fisheries habitat, pasture and rangeland improvements and wildlife habitat enhancement, with particular weight on projects that constitute grazing land conservation practices as defined by the USDA NRCS. This history would include social and economic factors driving past and present use of the watershed. <P>Conduct detailed analyses based on results of past grazing land conservation practices' impacts on water quality and flow, vegetation composition and structure and soil characteristics. Actual or estimated costs and benefits will be included.<P> Adapt the Water Erosion Prediction Project (WEPP) model for the study watershed and calibrate and parameterize the model to evaluate the physical parameters of watershed health, using synthesized past data. The adapted model(s) will be used to describe aggregate effects of past grazing land conservation practices and predict results of proposed sequences and locations of future grazing land conservation practices.<P>Assess various stakeholders' perceptions of more or less desirable conservation practices and other characteristics that correlate with watershed health criteria. <P>Develop an optimal set of grazing land conservation practices, including sequences and locations to achieve watershed health as defined for Asotin Creek. <P>Disseminate research findings through education and extension programs as well as scientific publications.

More information

Non-Technical Summary: In the Columbia River basin, native salmonid fish runs are the ultimate holistic criterion for watershed health. The presence of these species in Asotin Cr., despite current water quality limitations and over a century of grazing, logging, farming, residential and other uses, indicates we have much to learn from this watershed. This project will contribute to restoration and conservation of watershed health in Asotin Creek and provide a framework that can be applied to other grazing land watersheds in the US. With stakeholder input, we will develop site-specific socio-economic and bio-physical criteria for watershed health; evaluate existing and proposed conservation practices' influence on runoff, erosion and sediment delivery using Water Erosion Prediction Project (WEPP) models; examine perceptions of conservation options; and develop an optimal set of grazing land conservation practices to enhance and sustain watershed health. We will use more than 15 years of existing data, combined with modeling geo-spatial cumulative effects of conservation practices at a watershed scale, combining interdisciplinary biophysical and socio-economic analyses. Results from this study will benefit diverse stakeholders; ranchers, farmers, recreationists, Tribes and conservation interests as well as more distant stakeholders who benefit from the ecological (clean water and air, fish and wildlife) and economic products of this watershed. Study results will contribute to scientific understanding of grazing land management and refinement of the state and transition models developed for the relevant ecological sites described by the Washington NRCS. <P> Approach: Watershed health criteria for Asotin Creek will consist of biophysical and socio-economic elements, including cumulative effects resulting from combined effects of multiple activities over space or time. We have access to over 15 years of detailed data from soil surveys and rangeland ecological site development and mapping, Habitat Evaluation Procedure (HEP) analyses, a Model Watershed Program and 2 recent major watershed planning efforts. This is in addition to USGS, Washington Department of Fish and Wildlife, Department of Ecology and other sources of data on stream flow and sedimentation. Parameterizing the WEPP model with synthesized past water, land use and conservation practices data, we will improve or develop WEPP templates for rangeland conditions and conservation practices in this watershed. Then the WEPP model will be applied to past weather and land use and conservation practices data. Predicted results will be compared to the observed sediment and flow data. The WEPP templates will be re-evaluated and WEPP re-parameterized until WEPP can predict the past observed data reasonably. The watershed will be split into several smaller subbasins and connected with models such as CCHE1D, and GeoWEPP to incorporate GIS capability. With these WEPP templates we will model conservation practices to maximize desirable cumulative effects over time and space. Water quality and sediment production data, combined with geologic, climate, vegetation and soils data from different locations within the watershed will allow us to identify the most fragile and most disturbance-resistant areas within the watershed. By examining how these influences interact down-slope and downstream over time, we can identify where and when specific conservation practices will be most effective on specific land types. Effectiveness can be assessed in many cases by evaluating existing practices. Results can be aggregated across the watershed to approximate the overall potential of grazing land conservation practices to contribute to watershed health. Incorporating the needs of ESA listed fish ensures that solutions generated here would be applicable in less constrained watersheds. Socio-economic criteria will be developed via qualitative and quantitative interviews with producers and public representatives to examine perceptions of watershed health and determinate what makes a practice acceptable to stakeholders. The interaction of perceptions and physical suitability of a practice to specific land types will create spatially specific sets of prospective practices that can be presented in map, table, and simulated photographic formats. Integrating these various bio-physical and socio-economic analyses into an achievable strategy is complex. Much of our work will be guided by the definition of watershed health and associated parameters developed with our stakeholder-partners.

Investigators
Hardesty, Linda
Institution
Washington University
Start date
2008
End date
2011
Project number
WNP07603
Accession number
216076