Small commercial and non-commercial animal enterprises (SCAEs) raise a few beef cows, horses, pigs, sheep, poultry, and other animals on a few acres. These enterprises are often located in suburban areas of watersheds and show potential for degrading water quality through to increased bacterial, nitrogen, and phosphorus concentrations. SCAEs implement Best Management Practices (BNIPs) on a voluntary basis to control their water quality impacts. Off-stream watering areas, with animal access to streams, and covered manure storages are two BMPs which were analyzed in this thesis for effectiveness in reducing bacteria, nitrogen, and phosphorus from entering surface and groundwater in four SCAEs. The four cooperating SCAEs were located in the Tualatin River Basin, and the potential water quality improvements from implementing these two practices in all SCAEs in the basin were discussed. The BMP analyses use results from several studies. Two of these studies analyzed off-stream watering areas for reducing time animals spend watering at the stream. This time was measured and used to estimate the manure defecated in the stream. Reducing time animals spend at the stream decreases direct defecations in the stream and reduces water quality impacts of SCAEs. A third study analyzed a pasture pump as a possible off-stream watering device. It was analyzed for its ability to provide water to 27 Holstein dairy heifers without limiting water consumption. Daily water consumption from the pasture pump was not significantly different than daily consumption from an open water trough. A fourth study predicted the rainfall required to produce runoff from pastured areas in the Dairy-McKay Hydrological Unit Area within the Tualatin River Basin. These required rainfall amounts and runoff frequency were predicted for summer and winter soil conditions. The BMPs were analyzed for a variety of wet and dry conditions during the summer and winter. Off-stream watering areas were most effective in reducing water quality impacts of SCAEs for dry conditions during the summer and winter, while the covered manure storages were most effective during winter days of continuous rain. Off-stream watering areas reduced the time animals spent at the stream by 75%. Consequently, defecations at the stream were assumed to be reduced 75% and the SCAEs'water quality impacts decreased. Covered manure storages protect manure piles from rain and surface water runoff and prevent bacteria and nutrients from entering the stream or leaching to groundwater regardless of the weather. However, the amount prevented varies with weather conditions. An uncovered manure pile was estimated to cause no water quality impacts during dry weather. During wet weather, the bacteria and nutrients reaching the stream from an uncovered manure pile was estimated to be 60% of the quantity released. The maximum amount of nitrogen leaching to groundwater was estimated to be 10% of the amount applied to the pile since the previous rain. In addition to implementation costs of BMPs, there are changes in annual revenue and costs associated with the management changes. Partial budget analyses were conducted for the four SCAEs to determine their changes in annual monetary returns to management. Both BMPs resulted in negative changes in annual returns to management for all four enterprises. / Graduation date: 1994

Potential impacts of climate change on the water resources of the Pacific Northwest of the United States include earlier peak runoff, reduced summer flows, and increased winter flooding. An increase in impervious surfaces, accompanied by urban development, is known to decrease infiltration and increase surface runoff. Alterations of flow amount and pathways can alter water quality through dilution or flushing effects. I used the United States Environmental Protection Agency's Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) modeling system to investigate the relative importance of future climate change and land use change in determining the quantity and quality of freshwater resources in north western Oregon's Tualatin River Basin. The basin was chosen for this study because it is rapidly urbanizing and representative of other low-elevation basins in the region. BASINS models were calibrated and validated using historic flow and water quality data from 1991 to 2006. The goodness-of-fit for the calibrated hydrology, suspended sediment, and orthophosphate models was high, with coefficients of determination ranging from 0.72 to 0.93 in the calibration period. The calibrated models were run under a range of eight downscaled climate change, two regional land use change, and four combined scenarios. Results included average increases in winter flows of ten percent, decreases in summer flows of thirty-seven percent, and increases in fifth percentile flows of up to eighty percent as a result of climate change in the Tualatin River Basin. For land use change, the results included an increase in annual flows of twenty-one percent for the development-oriented scenario and a decrease of sixteen percent for the conservation-oriented scenario, with amplified changes at the sub-basin scale, including more than doubled winter flow. For combined scenarios of climate change and urban development, there is a projected increase in winter flows of up to seventy-one percent and decrease in summer flows of up to forty-eight percent. Changes in suspended sediment and orthophosphate loading broadly tracked hydrological changes, with winter increases and summer decreases. The results are relevant to regional planners interested in the long-term response of water resources to climate change and land use change at the basin scale.

Humans make decisions within ecosystems to enhance their well-being, but choices can lead to unintended consequences. The ecosystem services (ES) approach supports decision-making that considers all environmental goods and services. Many challenges remain in the implementation of the ES approach like how specific ES vary through space and time. We address this research problem using the Tualatin and Yamhill river basins in northwestern Oregon as a study area. Freshwater ES are quantified and mapped with the spatially-explicit ES modeling tool, Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST). In chapter II, we develop a simple urban land cover change modeling approach with selected stakeholder input. The products of this analysis are used in part to answer the question of how the freshwater ES of water yield, nutrient retention, and sediment retention will change in the future, and how their distribution potentially will change? In chapter III, these ES are modeled in InVEST using the land cover scenarios and three downscaled global climate models. The base period is 1981 to 2010 and the future period is 2036 to 2065. The models are calibrated to empirical estimates, and display different sensitivities to inputs. Water yield increases with higher rainfall but decreases with the highest temperature scenario. Nutrient export and retention estimates are positively correlated. In the Tualatin basin, more urban lands generally lead to increases in nutrient exports and retention. The effect is reversed in the Yamhill basin from much larger agricultural exports. Sediment exports and retention increase with higher winter rainfall but are negatively spatially correlated due to topographic effects. Simulation of a landscape scale installation of riparian buffers leads to decreases in exports and increases in retention. The distribution of the provision of freshwater ES remains unchanged throughout the scenarios. With few parameters in each InVEST model, all display a high degree of sensitivity. Parameterization is subject to high uncertainty even with calibrated values. We discuss the assumptions and limitations of InVEST's freshwater models. The spatially explicit nature of InVEST is its main advantage. This work coupled with other analyses in the study area can facilitate the identification of tradeoffs amongst ES leading to better ecosystem management.