Hulse, D., L. Goorjian, D. Richey, M. Flaxman, C. Hummon, Denis White, K. Freemark, J. Eilers, J. Bernert, K. Vache, J. Kaytes, and D. Diethelm. 1997. Possible Futures for the Muddy Creek Watershed, Benton County, Oregon. 90 pp. Institute for Sustainable Environment, University of Oregon, Eugene.
This report documents a two year case study research endeavor exploring how human population growth and land use change in the Muddy Creek Watershed of Benton County, Oregon may influence biodiversity and water quality. The case study illustrates a framework for helping local communities create alternative scenarios for land conservation and development. The project relied primarily on previously existing information and the regular participation of local stakeholders to produce a series of mapped possible future scenarios depicting land use in the Watershed in the year 2025. The possible futures were evaluated for their effects on biodiversity and water quality using ecological and hydrological process models with the best available information. The biodiversity evaluative model measured the change in potential habitat area for each of 234 breeding species, in each future scenario and the past, by calculating the ratio of future or past habitat area to present habitat area. The water quality evaluative model, a non-point pollutant source geographic information system model, simulated a series of five storm events to calculate the mean pollutant load for each of the five possible futures, present and past. The model assessed volume of surface flows and levels of total suspended solids and phosphorous, using field data collected from base line flows and two storm event flows monitored in 1996. Results from the biodiversity model show that all native species have at least some habitat in all future land use scenarios. However, if land use trends in the Watershed continue unchanged (Plan Trend Future) or become more highly developed over the next 30 years (Moderate and High Development Futures), there will be an increased risk to abundance of the 212 extant native species, particularly birds, mammals and amphibians. Of the 220 species native to the Watershed throughout its recent history, 26 species have lost more than half of their habitat since ca. 1850. Under the High Development Future, 12 species are estimated to lose more than half of their present habitat in the next 30 years. Only 2 species - the California Condor and Marbled Murrelet - are common to both lists. This acceleration and shifting of risk from one set of species to another suggests that the kinds of habitat changes from past to present are different than those envisioned in the possible futures. Results from the water quality model show increases in volume of surface water runoff and total suspended solids under the Moderate and High Development Futures in sub-basins undergoing significantly increased residential development or having a high percentage of area in erosive soils on steep slopes. Crops located on steep slopes were the greatest contributors of total suspended solids and total phosphorus in the agricultural lowlands. Land uses on gentle slopes or in natural vegetation were the lowest contributors of total suspended solids and total phosphorus. In summary, if the residents of the Muddy Creek Watershed desire a future presenting no greater risk to biodiversity and water quality than the present pattern of land use, then they should plan toward a future with a land use pattern between the Moderate Conservation and the Plan Trend Future for biodiversity protection, and between the Moderate Conservation and the High Conservation Future for water quality protection.