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• 1. [Article] Physiological impacts of groundwater and surface water application on desert graminoids of different geographic origin

  Desert plant communities are among the most sensitive to changes in soil water conditions. In areas with shallow aquifers, it is important to understand both the effects of groundwater alterations on ...

  Citation × Citation Citation Abstract Copy Title: Physiological impacts of groundwater and surface water application on desert graminoids of different geographic origin Author: Abdallah, Mohamed (Mohamed Ahmed B.) Desert plant communities are among the most sensitive to changes in soil water conditions. In areas with shallow aquifers, it is important to understand both the effects of groundwater alterations on vegetation and how changes in surface-soil water affect plant water uptake. Studies in arid environments have evaluated the effect of groundwater variation and simulated precipitation on plant production and vegetation condition but it is not clear if plants respond equally to the availability of surface water or groundwater. This study was conducted in a greenhouse to evaluate growth and physiology of three desert graminoids (Distichlis spicata, Leymus triticoides, and Juncus arcticus) as affected by surface water availability (mimicking precipitation) or subsurface water availability (mimicking groundwater). The species of study are amply distributed in wetlands and open rangelands of western USA and were collected from two sources of ecological distribution: an area near Bishop, California, and an area near Burns, Oregon. The Bishop, California area has a characteristic shallow aquifer and plants in this area are considered somewhat dependent on groundwater. The Burns, Oregon, area sustains the same species but in a variety of soil moisture conditions. We had two general hypotheses for this study: 1) that the use of surface water is favored over groundwater and 2) that there are ecotypic differences in the response of the species to water availability. The first hypothesis was partially supported by the results of the study, but variability existed among species. However, when all species had equal access to both surface soil water and groundwater plants tended to preferentially use surface water. The second hypothesis was clearly supported by our results. Although the mechanism is not clear, it is possible that an area with periodic and predictable shallow groundwater underlying a dry or saline soil layer, such as the California site, might favor plant ecotypes with high proficiency in water acquisition by deeper roots. Knowledge of water use characteristics of vegetation is essential to provide management guidelines for areas where plants depend on both surface-soil water and groundwater. This study contributed to that knowledge. Further studies on ecotypic variation and an expansion to different species that inhabit areas with shallow aquifers are recommended. Title: Physiological impacts of groundwater and surface water application on desert graminoids of different geographic origin Author: Abdallah, Mohamed (Mohamed Ahmed B.) Desert plant communities are among the most sensitive to changes in soil water conditions. In areas with shallow aquifers, it is important to understand both the effects of groundwater alterations on vegetation and how changes in surface-soil water affect plant water uptake. Studies in arid environments have evaluated the effect of groundwater variation and simulated precipitation on plant production and vegetation condition but it is not clear if plants respond equally to the availability of surface water or groundwater. This study was conducted in a greenhouse to evaluate growth and physiology of three desert graminoids (Distichlis spicata, Leymus triticoides, and Juncus arcticus) as affected by surface water availability (mimicking precipitation) or subsurface water availability (mimicking groundwater). The species of study are amply distributed in wetlands and open rangelands of western USA and were collected from two sources of ecological distribution: an area near Bishop, California, and an area near Burns, Oregon. The Bishop, California area has a characteristic shallow aquifer and plants in this area are considered somewhat dependent on groundwater. The Burns, Oregon, area sustains the same species but in a variety of soil moisture conditions. We had two general hypotheses for this study: 1) that the use of surface water is favored over groundwater and 2) that there are ecotypic differences in the response of the species to water availability. The first hypothesis was partially supported by the results of the study, but variability existed among species. However, when all species had equal access to both surface soil water and groundwater plants tended to preferentially use surface water. The second hypothesis was clearly supported by our results. Although the mechanism is not clear, it is possible that an area with periodic and predictable shallow groundwater underlying a dry or saline soil layer, such as the California site, might favor plant ecotypes with high proficiency in water acquisition by deeper roots. Knowledge of water use characteristics of vegetation is essential to provide management guidelines for areas where plants depend on both surface-soil water and groundwater. This study contributed to that knowledge. Further studies on ecotypic variation and an expansion to different species that inhabit areas with shallow aquifers are recommended. Close

• 2. [Article] The effects of land use on mineral flat wetland hydrologic processes in lowland agricultural catchments

  Hydrologic processes within mineral flat wetlands, along with their connections to groundwater and downstream surface water in lowland agricultural catchments are poorly understood, particularly under ...

  Citation × Citation Citation Abstract Copy Title: The effects of land use on mineral flat wetland hydrologic processes in lowland agricultural catchments Author: Marshall, Sarah M. (Sarah Marie) Hydrologic processes within mineral flat wetlands, along with their connections to groundwater and downstream surface water in lowland agricultural catchments are poorly understood, particularly under different land uses. In the three field studies included in this thesis, we examined infiltration, wetland hydroperiod, groundwater recharge dynamics, surface runoff generation, and water quality in mineral flat wetlands using a combination of soil and hydrometric measurements, stable isotope tracers, and water chemistry analysis. Our overarching objectives were to examine, for mineral flat wetlands under native prairie, farmed grassland, and restored prairie land cover: 1) how different land management influences infiltration and wetland hydroperiod at the plot scale, 2) the effects of land use on seasonal groundwater-surface water dynamics at the field scale, and 3) seasonal variation in runoff sources and nutrient transport from native prairie and farmed wetlands at the small catchment scale. At the plot scale, our results suggest that edaphic factors, particularly those related to soil structure, are strongly associated with wetland infiltration and overall hydroperiod across least-altered prairie, farmed, and restored prairie mineral flat wetlands. The hydroperiod metrics we examined were generally more sensitive to level of site disturbance than land use alone. At the field scale, our results indicate that, in spite of land use differences and slight variations in soil stratigraphy, many similarities exist in overall wetland hydroperiod, water sources and evaporation rates for mineral flat wetlands in the Willamette Valley lowlands. Isotopic evidence suggests that the greatest degree of groundwater-surface water mixing occurs in the upper 0.5 m of the saturated soil profile across sites under all land uses. Finally, at the small catchment scale, farmed wetland runoff was isotopically similar to field surface water for most of the wet season, indicating that saturation excess was an important runoff generation process. Prairie wetland runoff was isotopically similar to upstream water throughout the winter, and briefly similar to shallow groundwater and surface water within the wetland in mid-spring. Throughout the wet season, elevated nitrate, sulfate, and chloride concentrations were observed in groundwater and surface water at the farm site, and deeper groundwater at the prairie site. Upstream-downstream runoff chemistry remained similar throughout the wet season at the prairie site. Farm site runoff chemistry reflected the dominant water source within the farm field throughout the wet season. Our findings suggest that, while surface water pathways dominate runoff from wetland flats under farm land use, large wetland flat fields have a high potential to absorb, store, and process nutrients and agrochemicals from on-site and nearby off-site chemical inputs. Mineral flats that maintain wetland hydrology in spite of farm use represent a unique balance between agricultural production and preservation of some of the water storage and delay, and water quality-related ecosystem services once provided at a much larger scale in the Willamette Valley lowlands. We anticipate that results of this work will lead to better understanding of key site-scale edaphic and hydrologic factors to consider when prioritizing and managing sites for restoration, and how site disturbance under a variety of land uses may impact different hydrologic processes and components of the wetland hydroperiod. Additionally, our results provide a better understanding of how land use affects seasonal runoff generation processes in mineral flat wetlands, and the water quality implications of modifying groundwater and surface water connectivity between mineral flats and surrounding surface drainage networks. Title: The effects of land use on mineral flat wetland hydrologic processes in lowland agricultural catchments Author: Marshall, Sarah M. (Sarah Marie) Hydrologic processes within mineral flat wetlands, along with their connections to groundwater and downstream surface water in lowland agricultural catchments are poorly understood, particularly under different land uses. In the three field studies included in this thesis, we examined infiltration, wetland hydroperiod, groundwater recharge dynamics, surface runoff generation, and water quality in mineral flat wetlands using a combination of soil and hydrometric measurements, stable isotope tracers, and water chemistry analysis. Our overarching objectives were to examine, for mineral flat wetlands under native prairie, farmed grassland, and restored prairie land cover: 1) how different land management influences infiltration and wetland hydroperiod at the plot scale, 2) the effects of land use on seasonal groundwater-surface water dynamics at the field scale, and 3) seasonal variation in runoff sources and nutrient transport from native prairie and farmed wetlands at the small catchment scale. At the plot scale, our results suggest that edaphic factors, particularly those related to soil structure, are strongly associated with wetland infiltration and overall hydroperiod across least-altered prairie, farmed, and restored prairie mineral flat wetlands. The hydroperiod metrics we examined were generally more sensitive to level of site disturbance than land use alone. At the field scale, our results indicate that, in spite of land use differences and slight variations in soil stratigraphy, many similarities exist in overall wetland hydroperiod, water sources and evaporation rates for mineral flat wetlands in the Willamette Valley lowlands. Isotopic evidence suggests that the greatest degree of groundwater-surface water mixing occurs in the upper 0.5 m of the saturated soil profile across sites under all land uses. Finally, at the small catchment scale, farmed wetland runoff was isotopically similar to field surface water for most of the wet season, indicating that saturation excess was an important runoff generation process. Prairie wetland runoff was isotopically similar to upstream water throughout the winter, and briefly similar to shallow groundwater and surface water within the wetland in mid-spring. Throughout the wet season, elevated nitrate, sulfate, and chloride concentrations were observed in groundwater and surface water at the farm site, and deeper groundwater at the prairie site. Upstream-downstream runoff chemistry remained similar throughout the wet season at the prairie site. Farm site runoff chemistry reflected the dominant water source within the farm field throughout the wet season. Our findings suggest that, while surface water pathways dominate runoff from wetland flats under farm land use, large wetland flat fields have a high potential to absorb, store, and process nutrients and agrochemicals from on-site and nearby off-site chemical inputs. Mineral flats that maintain wetland hydrology in spite of farm use represent a unique balance between agricultural production and preservation of some of the water storage and delay, and water quality-related ecosystem services once provided at a much larger scale in the Willamette Valley lowlands. We anticipate that results of this work will lead to better understanding of key site-scale edaphic and hydrologic factors to consider when prioritizing and managing sites for restoration, and how site disturbance under a variety of land uses may impact different hydrologic processes and components of the wetland hydroperiod. Additionally, our results provide a better understanding of how land use affects seasonal runoff generation processes in mineral flat wetlands, and the water quality implications of modifying groundwater and surface water connectivity between mineral flats and surrounding surface drainage networks. Close

• 3. [Article] What Lies Below: Options to Improve Sustainable Management of U.S./Mexico TransboundaryAquifers

  Globally, as surface water quality and quantity diminishes there is increasing reliance on groundwater to buffer water demands of growing populations. Today in many arid regions around the world aquifer ...

  Citation × Citation Citation Abstract Copy Title: What Lies Below: Options to Improve Sustainable Management of U.S./Mexico TransboundaryAquifers Author: Welch, Christina, N. Globally, as surface water quality and quantity diminishes there is increasing reliance on groundwater to buffer water demands of growing populations. Today in many arid regions around the world aquifer pumping rates far exceed recharge rates. Often the groundwater is nonrenewable, or thousands of years old. Despite the known hydrologic connection between surface and groundwater, existing institutions and laws governing surface water are poorly equipped to manage groundwater. While there are more than 600 international treaties governing surface water, only one treaty worldwide explicitly addresses groundwater allocation. Like many other regions of the world, the treaties covering the Paseo del Norte region shared between Mexico and the United States allocate the quantity and timing of surface water deliveries, yet fail to regulate groundwater abstraction. The three transboundary aquifers shared by two countries and three states (New Mexico/U.S., Texas/U.S., and Chihuahua/MX) within Paseo del Norte study area present an ideal microcosm to closer examine water management institutions across the local, state, national, and international scales. This research assesses the United States and Mexico’s institutional capacity to manage groundwater across each scale. The problem is imminent since the Hueco Bolson transboundary aquifer is the primary source of drinking water for nearly 2 million people and the fresh water is predicted to be completely depleted between 2020-2050. The ultimate objective is to identify which future legal, scientific and economic options can best contribute to more sustainable management of transboundary aquifers without compromising water security in both countries. This research proposes three major paths to move forward: the first step is to increase public awareness of the aquifer exploitation problem; second, for water managers to accurately plan for future water demands there should be a binational groundwater model built by scientists on both sides of the border; third, an international treaty or regional joint agreement is necessary to legally support groundwater management efforts. Title: What Lies Below: Options to Improve Sustainable Management of U.S./Mexico TransboundaryAquifers Author: Welch, Christina, N. Globally, as surface water quality and quantity diminishes there is increasing reliance on groundwater to buffer water demands of growing populations. Today in many arid regions around the world aquifer pumping rates far exceed recharge rates. Often the groundwater is nonrenewable, or thousands of years old. Despite the known hydrologic connection between surface and groundwater, existing institutions and laws governing surface water are poorly equipped to manage groundwater. While there are more than 600 international treaties governing surface water, only one treaty worldwide explicitly addresses groundwater allocation. Like many other regions of the world, the treaties covering the Paseo del Norte region shared between Mexico and the United States allocate the quantity and timing of surface water deliveries, yet fail to regulate groundwater abstraction. The three transboundary aquifers shared by two countries and three states (New Mexico/U.S., Texas/U.S., and Chihuahua/MX) within Paseo del Norte study area present an ideal microcosm to closer examine water management institutions across the local, state, national, and international scales. This research assesses the United States and Mexico’s institutional capacity to manage groundwater across each scale. The problem is imminent since the Hueco Bolson transboundary aquifer is the primary source of drinking water for nearly 2 million people and the fresh water is predicted to be completely depleted between 2020-2050. The ultimate objective is to identify which future legal, scientific and economic options can best contribute to more sustainable management of transboundary aquifers without compromising water security in both countries. This research proposes three major paths to move forward: the first step is to increase public awareness of the aquifer exploitation problem; second, for water managers to accurately plan for future water demands there should be a binational groundwater model built by scientists on both sides of the border; third, an international treaty or regional joint agreement is necessary to legally support groundwater management efforts. Close

• 4. [Article] Surface Water Interaction with “Confined” Columbia River Basalt Aquifers – Impacts to Streams from Declining Groundwater Levels near Mosier, Oregon

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: Surface Water Interaction with “Confined” Columbia River Basalt Aquifers – Impacts to Streams from Declining Groundwater Levels near Mosier, Oregon Author: Lite Jr., Kenneth E. Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: Surface Water Interaction with “Confined” Columbia River Basalt Aquifers – Impacts to Streams from Declining Groundwater Levels near Mosier, Oregon Author: Lite Jr., Kenneth E. Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close

• 5. [Article] Characterization of spring and surface water conductance : Whychus Creek from Pole Creek Ditch to the Camp Polk Meadow riparian area

  Poster from the 2006 Cascades student poster session

  Citation × Citation Citation Abstract Copy Title: Characterization of spring and surface water conductance : Whychus Creek from Pole Creek Ditch to the Camp Polk Meadow riparian area Author: Brown, Jason Poster from the 2006 Cascades student poster session Title: Characterization of spring and surface water conductance : Whychus Creek from Pole Creek Ditch to the Camp Polk Meadow riparian area Author: Brown, Jason Poster from the 2006 Cascades student poster session Close

• 6. [Article] A Collaborative Effort to Evaluate Water Resources in the Lower Siuslaw Watershed

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: A Collaborative Effort to Evaluate Water Resources in the Lower Siuslaw Watershed Author: Livesay, Dave, Miller, Mike, Nelson, Dennis, Moellendorf, Suzanne Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: A Collaborative Effort to Evaluate Water Resources in the Lower Siuslaw Watershed Author: Livesay, Dave, Miller, Mike, Nelson, Dennis, Moellendorf, Suzanne Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close

• 7. [Article] Geomorphic and Climatic Controls on Water Temperature and Streambed Scour, Copper River Delta, Alaska : Implications for Understanding Climate Change Impacts to the Pacific Salmon Egg Incubation Environment

  Pacific salmon (Oncorhynchus spp.) face numerous challenges associated with climate change. Most research has emphasized the potential effects of elevated summer water temperatures; however, climatic changes ...

  Citation × Citation Citation Abstract Copy Title: Geomorphic and Climatic Controls on Water Temperature and Streambed Scour, Copper River Delta, Alaska : Implications for Understanding Climate Change Impacts to the Pacific Salmon Egg Incubation Environment Author: Adelfio, Luca A. Pacific salmon (Oncorhynchus spp.) face numerous challenges associated with climate change. Most research has emphasized the potential effects of elevated summer water temperatures; however, climatic changes are also projected to significantly alter incubation and rearing habitats during the late autumn, winter, and spring months ("the incubation period"). Along the southern coast of Alaska, projected climatic changes include increases in the frequency of above freezing winter temperatures and reductions in low elevation snowpack. These changes are expected to impact the hydrology of salmon streams by increasing both water temperatures and the magnitude and frequency of winter floods. Projected increases in water temperature may accelerate embryo development, impacting juvenile viability. More powerful and more frequent winter floods could reduce the survival of salmon eggs by increasing streambed scour. Here, I investigate climatic and geomorphic controls of water temperature and potential scour depth at salmon spawning and rearing sites on the Copper River Delta, a large coastal foreland in Southcentral Alaska. In chapter 2, I utilized surface water temperature data collected at 18 sites to test the abilities of regression models to project year-round water temperature metrics based on catchment characteristics (elevation, slope, area, percent lake area) and air-water temperature correlations. Considerable variability in water temperature was observed on spatial and temporal scales. Both temperature maxima and the frequency of freezing conditions were positively correlated with percent lake area and negatively correlated with catchment elevation and slope. Sites with upwelling groundwater and sites with high-relief, high elevation catchments exhibited lower thermal sensitivity and water temperatures are anticipated to be less impacted by projected climatic changes. In chapter 3, I utilized surface and streambed water temperature data collected at 8 spawning sites to compare water temperatures during incubation periods under climatological mean ("severe winter") and anomalously warm ("mild winter") conditions. I also collected stream stage and channel geometry data at a subset of 3 sites and calculated streambed scour at bankfull discharge. The magnitude and seasonality of accumulated thermal units (°C/day) (ATU) within spawning gravels varied significantly between severe and mild winters at shallow flowpath sites, but not at upwelling groundwater sites. When seasonal snow and ice was absent, increases in spring ATU at shallow flowpath sites were particularly significant. Modelled mean scour depths varied from 3 to 72 cm, suggesting the impacts of scour on egg mortality will be variable across the landscape. I conclude that the impacts of projected climatic changes are likely to vary in magnitude across the Copper River Delta, even at small spatial scales, due to heterogeneity in climatic and geomorphic controls. Title: Geomorphic and Climatic Controls on Water Temperature and Streambed Scour, Copper River Delta, Alaska : Implications for Understanding Climate Change Impacts to the Pacific Salmon Egg Incubation Environment Author: Adelfio, Luca A. Pacific salmon (Oncorhynchus spp.) face numerous challenges associated with climate change. Most research has emphasized the potential effects of elevated summer water temperatures; however, climatic changes are also projected to significantly alter incubation and rearing habitats during the late autumn, winter, and spring months ("the incubation period"). Along the southern coast of Alaska, projected climatic changes include increases in the frequency of above freezing winter temperatures and reductions in low elevation snowpack. These changes are expected to impact the hydrology of salmon streams by increasing both water temperatures and the magnitude and frequency of winter floods. Projected increases in water temperature may accelerate embryo development, impacting juvenile viability. More powerful and more frequent winter floods could reduce the survival of salmon eggs by increasing streambed scour. Here, I investigate climatic and geomorphic controls of water temperature and potential scour depth at salmon spawning and rearing sites on the Copper River Delta, a large coastal foreland in Southcentral Alaska. In chapter 2, I utilized surface water temperature data collected at 18 sites to test the abilities of regression models to project year-round water temperature metrics based on catchment characteristics (elevation, slope, area, percent lake area) and air-water temperature correlations. Considerable variability in water temperature was observed on spatial and temporal scales. Both temperature maxima and the frequency of freezing conditions were positively correlated with percent lake area and negatively correlated with catchment elevation and slope. Sites with upwelling groundwater and sites with high-relief, high elevation catchments exhibited lower thermal sensitivity and water temperatures are anticipated to be less impacted by projected climatic changes. In chapter 3, I utilized surface and streambed water temperature data collected at 8 spawning sites to compare water temperatures during incubation periods under climatological mean ("severe winter") and anomalously warm ("mild winter") conditions. I also collected stream stage and channel geometry data at a subset of 3 sites and calculated streambed scour at bankfull discharge. The magnitude and seasonality of accumulated thermal units (°C/day) (ATU) within spawning gravels varied significantly between severe and mild winters at shallow flowpath sites, but not at upwelling groundwater sites. When seasonal snow and ice was absent, increases in spring ATU at shallow flowpath sites were particularly significant. Modelled mean scour depths varied from 3 to 72 cm, suggesting the impacts of scour on egg mortality will be variable across the landscape. I conclude that the impacts of projected climatic changes are likely to vary in magnitude across the Copper River Delta, even at small spatial scales, due to heterogeneity in climatic and geomorphic controls. Close

• 8. [Article] Experiences in implementing the White Method : estimating evapotranspiration using fluctuations of water table elevation

  Evapotranspiration (ET) is the process by which water is transferred from land to the atmosphere. ET is the second most important component of a hydrologic budget and remains difficult to estimate. The ...

  Citation × Citation Citation Abstract Copy Title: Experiences in implementing the White Method : estimating evapotranspiration using fluctuations of water table elevation Author: Kollen, Jacob K. Evapotranspiration (ET) is the process by which water is transferred from land to the atmosphere. ET is the second most important component of a hydrologic budget and remains difficult to estimate. The primary objective of this project was to determine the limitations of estimating ET from water table elevation fluctuations analyzed using the White Method (White, 1932). Secondary objectives include: determining if specific yield is a function of water table depth, investigating the effect of hysteresis on water table fluctuation shape, estimating groundwater recharge rate, and using vegetation data to gain clues regarding spatiotemporal water availability. They are 5 major results from this investigation. Nachabe's modified soil moisture balance (Nachabe et al. 2005) outperformed the classical White Method (White, 1932) in ability to estimate a daily rate of evapotranspiration. Specific yield is not a constant and changes with water table depth below ground surface level. Hysteresis can explain the break in slope in water table rise observed during the night of many records of water table fluctuations. The White Method is more suitable to estimate groundwater upwelling rather than evapotranspiration. Finally, vegetation sampling can provide clues to intra-seasonal and inter-seasonal water availability across a site. Title: Experiences in implementing the White Method : estimating evapotranspiration using fluctuations of water table elevation Author: Kollen, Jacob K. Evapotranspiration (ET) is the process by which water is transferred from land to the atmosphere. ET is the second most important component of a hydrologic budget and remains difficult to estimate. The primary objective of this project was to determine the limitations of estimating ET from water table elevation fluctuations analyzed using the White Method (White, 1932). Secondary objectives include: determining if specific yield is a function of water table depth, investigating the effect of hysteresis on water table fluctuation shape, estimating groundwater recharge rate, and using vegetation data to gain clues regarding spatiotemporal water availability. They are 5 major results from this investigation. Nachabe's modified soil moisture balance (Nachabe et al. 2005) outperformed the classical White Method (White, 1932) in ability to estimate a daily rate of evapotranspiration. Specific yield is not a constant and changes with water table depth below ground surface level. Hysteresis can explain the break in slope in water table rise observed during the night of many records of water table fluctuations. The White Method is more suitable to estimate groundwater upwelling rather than evapotranspiration. Finally, vegetation sampling can provide clues to intra-seasonal and inter-seasonal water availability across a site. Close

• 9. [Article] Groundwater Storage and Flow in an Unconfined Pumice Aquifer, Antelope Unit, Chemult Ranger District, Winema-Fremont National Forest, Oregon

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: Groundwater Storage and Flow in an Unconfined Pumice Aquifer, Antelope Unit, Chemult Ranger District, Winema-Fremont National Forest, Oregon Author: Cummings, Michael Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: Groundwater Storage and Flow in an Unconfined Pumice Aquifer, Antelope Unit, Chemult Ranger District, Winema-Fremont National Forest, Oregon Author: Cummings, Michael Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close