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• 1. [Article] An Ecoregion-Based Reference Condition and Classification Scheme for Determining Nutrient Criteria in Oregon Lakes

  The anthropogenic introduction of nutrients to water bodies has been shown to alter the structure and function of natural aquatic ecosystems, yet national EPA lake and reservoir nutrient criteria remain ...

  Citation × Citation Citation Abstract Copy Title: An Ecoregion-Based Reference Condition and Classification Scheme for Determining Nutrient Criteria in Oregon Lakes Author: Brenner, Jacqueline M. The anthropogenic introduction of nutrients to water bodies has been shown to alter the structure and function of natural aquatic ecosystems, yet national EPA lake and reservoir nutrient criteria remain too broad for effective regional water quality management. This study uses a reference site approach to propose numeric nutrient criteria for concentrations of total nitrogen (TN) and total phosphorus (TP) specifically applicable to lakes and reservoirs in Oregon. Oregon lake watersheds with existing lakewater nutrient data were characterized using GIS techniques to eliminate lakes with known point and non-point sources of anthropogenic nutrient contributions, resulting in 98 minimally or least-altered Oregon lakes. These minimally altered lakes were used as reference sites for their corresponding Omernik Level III ecoregion based on majority ecoregion composition of the lake watershed. CART regression and other statistical procedures were used to relate existing data on summer nutrient concentrations to reference site factors, including: water residence time, soil properties, elevation, lake depth, precipitation, and watershed deciduous forests and wetlands. Lake classifications from this analysis were only significantly related to precipitation and supported aggregate ecoregion groupings of the Western Forested Mountains (Coast Range, Willamette Valley, Cascades, Klamath Mountains, and Blue Mountains), Xeric West (Northern Basin and Range, Columbia Plateau, and Snake River Plain), and Eastern Cascades were used to set ecoregional criteria for TP. For TN, the Eastern Cascades were not significantly different from the Xeric West and aggregated into the Xeric West ecoregion. As per EPA guidelines, the 75th percentile of reference site nutrient concentrations in an ecoregion were used to set ecoregional nutrient criteria with the following results; Western Forested Mountains: 11 μg TP/L and 277 μg TN/L; Eastern Cascades: 78.5 μg TP/L; and Xeric West: 490 μg TP/L and 760 μgTN/L. Nutrient concentrations in a random sample of Oregon lakes taken from EPA's 2007 and 2012 National Lake Assessment surveys were assessed using the proposed criteria. Statewide, 21- 37% of lakes had TP below criteria and 40 - 64% of lakes had TN below criteria in the two surveys. These results contribute to nutrient management efforts and inform agency scientists and decision makers regarding the complexity of nutrient – land use relationships in lakes and their watersheds. Title: An Ecoregion-Based Reference Condition and Classification Scheme for Determining Nutrient Criteria in Oregon Lakes Author: Brenner, Jacqueline M. The anthropogenic introduction of nutrients to water bodies has been shown to alter the structure and function of natural aquatic ecosystems, yet national EPA lake and reservoir nutrient criteria remain too broad for effective regional water quality management. This study uses a reference site approach to propose numeric nutrient criteria for concentrations of total nitrogen (TN) and total phosphorus (TP) specifically applicable to lakes and reservoirs in Oregon. Oregon lake watersheds with existing lakewater nutrient data were characterized using GIS techniques to eliminate lakes with known point and non-point sources of anthropogenic nutrient contributions, resulting in 98 minimally or least-altered Oregon lakes. These minimally altered lakes were used as reference sites for their corresponding Omernik Level III ecoregion based on majority ecoregion composition of the lake watershed. CART regression and other statistical procedures were used to relate existing data on summer nutrient concentrations to reference site factors, including: water residence time, soil properties, elevation, lake depth, precipitation, and watershed deciduous forests and wetlands. Lake classifications from this analysis were only significantly related to precipitation and supported aggregate ecoregion groupings of the Western Forested Mountains (Coast Range, Willamette Valley, Cascades, Klamath Mountains, and Blue Mountains), Xeric West (Northern Basin and Range, Columbia Plateau, and Snake River Plain), and Eastern Cascades were used to set ecoregional criteria for TP. For TN, the Eastern Cascades were not significantly different from the Xeric West and aggregated into the Xeric West ecoregion. As per EPA guidelines, the 75th percentile of reference site nutrient concentrations in an ecoregion were used to set ecoregional nutrient criteria with the following results; Western Forested Mountains: 11 μg TP/L and 277 μg TN/L; Eastern Cascades: 78.5 μg TP/L; and Xeric West: 490 μg TP/L and 760 μgTN/L. Nutrient concentrations in a random sample of Oregon lakes taken from EPA's 2007 and 2012 National Lake Assessment surveys were assessed using the proposed criteria. Statewide, 21- 37% of lakes had TP below criteria and 40 - 64% of lakes had TN below criteria in the two surveys. These results contribute to nutrient management efforts and inform agency scientists and decision makers regarding the complexity of nutrient – land use relationships in lakes and their watersheds. Close

• 2. [Article] Mapping and lithologic interpretation of the Territorial Sea, Oregon

  Seafloor lithologic maps have been widely used to identify conservation sites. In this study, a lithologic interpretation of Oregon's territorial seafloor was created as an interim product in response ...

  Citation × Citation Citation Abstract Copy Title: Mapping and lithologic interpretation of the Territorial Sea, Oregon Author: Agapito, Melinda T. Seafloor lithologic maps have been widely used to identify conservation sites. In this study, a lithologic interpretation of Oregon's territorial seafloor was created as an interim product in response to the need for a comprehensive lithologic map that will be used in the identification, evaluation and design of marine reserves in Oregon. While future multibeam mapping of the Oregon Territorial Sea will likely replace this product in the next few years, the ground truth data from which the map is constructed will continue in use in future efforts. This mapping project utilized a classical geologic approach aided by GIS technology in which all relevant thematic geologic layers were applied to interpret patterns of seafloor lithology. The discovery of approximately 9,600 NOS bottom samples from the National Ocean Service (NOS) historic hydrographic smooth sheet archives has tremendously improved upon the original sample dataset (305 bottom samples) used in previous characterization of Oregon's territorial seabed. Supplementing the NOS bottom samples, other existing datasets including historic kelp distribution (used as proxy for rock), a triangulated irregular network (TIN) surface model derived from bathymetric soundings, rock outcrops digitized from 0.5 meter aerial photos, subsurface structure, and the adjacent onshore Oregon digital geologic map were used. While the collection of smooth sheet data from historic surveys utilized leadline sampling techniques and traditional navigation methods such as three-point sextant positioning, it was observed that the typical positional error averaged ~28 meters relative to contemporary aerial photography where comparison was possible. GIS software was used for simultaneous display of varied thematic layers, qualitative interpretation, quantitative accuracy assessment, and density mapping processes in this project. This current mapping effort showed that the NOS "smooth sheet" data collected from 1858 to 1958 compares well with modern data and that the NOS datasets and methods are able to capture the general outlines of rocky outcrops particularly in shallow areas. The territorial lithologic map shows a reasonable overall accuracy of 64 % relative to existing habitat interpretation of rocky reefs based on high-resolution multibeam data. Furthermore, the NOS bottom samples provide an opportunity to map additional sediment types that are not represented in the existing Surficial Geologic Habitat (SGH) map of the territorial sea. Finally, a companion product to the maps, a composite density map was created from the underlying datasets (kelp, bathymetry and bottom samples) to represent the spatial variation in data quality and quantity used in the interpretation of seafloor lithology. It is anticipated that the data obtained from this study will serve as a useful tool for scientific investigation and management efforts such as the ocean zoning in the nearshore region of the Oregon coast, which includes the upcoming designation and evaluation of marine reserves. Title: Mapping and lithologic interpretation of the Territorial Sea, Oregon Author: Agapito, Melinda T. Seafloor lithologic maps have been widely used to identify conservation sites. In this study, a lithologic interpretation of Oregon's territorial seafloor was created as an interim product in response to the need for a comprehensive lithologic map that will be used in the identification, evaluation and design of marine reserves in Oregon. While future multibeam mapping of the Oregon Territorial Sea will likely replace this product in the next few years, the ground truth data from which the map is constructed will continue in use in future efforts. This mapping project utilized a classical geologic approach aided by GIS technology in which all relevant thematic geologic layers were applied to interpret patterns of seafloor lithology. The discovery of approximately 9,600 NOS bottom samples from the National Ocean Service (NOS) historic hydrographic smooth sheet archives has tremendously improved upon the original sample dataset (305 bottom samples) used in previous characterization of Oregon's territorial seabed. Supplementing the NOS bottom samples, other existing datasets including historic kelp distribution (used as proxy for rock), a triangulated irregular network (TIN) surface model derived from bathymetric soundings, rock outcrops digitized from 0.5 meter aerial photos, subsurface structure, and the adjacent onshore Oregon digital geologic map were used. While the collection of smooth sheet data from historic surveys utilized leadline sampling techniques and traditional navigation methods such as three-point sextant positioning, it was observed that the typical positional error averaged ~28 meters relative to contemporary aerial photography where comparison was possible. GIS software was used for simultaneous display of varied thematic layers, qualitative interpretation, quantitative accuracy assessment, and density mapping processes in this project. This current mapping effort showed that the NOS "smooth sheet" data collected from 1858 to 1958 compares well with modern data and that the NOS datasets and methods are able to capture the general outlines of rocky outcrops particularly in shallow areas. The territorial lithologic map shows a reasonable overall accuracy of 64 % relative to existing habitat interpretation of rocky reefs based on high-resolution multibeam data. Furthermore, the NOS bottom samples provide an opportunity to map additional sediment types that are not represented in the existing Surficial Geologic Habitat (SGH) map of the territorial sea. Finally, a companion product to the maps, a composite density map was created from the underlying datasets (kelp, bathymetry and bottom samples) to represent the spatial variation in data quality and quantity used in the interpretation of seafloor lithology. It is anticipated that the data obtained from this study will serve as a useful tool for scientific investigation and management efforts such as the ocean zoning in the nearshore region of the Oregon coast, which includes the upcoming designation and evaluation of marine reserves. Close