Results for “General Technical Report” — Page 17

USGS1993

Map showing sediment isopachs in the deep-sea basins of the Pacific continental margin, Cape Mendocino to Point Conception

The U.S. Geological Survey conducted a series of cruises, EEZSCAN 84 (EEZ-SCAN 84 Scientific Staff, 1986), to collect reconnaissance data on the newly proclaimed Exclusive Economic Zone (EEZ), the area out to 200 nautical miles from the coastline of the United States. The cruises systematically surveyed the entire conterminous United States west coast EEZ using the Geological Long-Range Inclined Asdic (GLORIA) side-scan sonar, a 160-in 3 airgun seismic-reflection profiler, a 3.5-kHz high-resolution seismic-reflection profiler, a 10-kHz echo sounder, and a proton-precession magnetometer. The nominal trackline spacing throughout the survey was 30 km. Derivative maps of sediment thickness (I-2089-A, I-2090-A, I-2091-A) and depth to basement (I-2089-B, I-2090-B, I-2091-B) in the basins of the west coast EEZ were compiled from both the sonar-image dala and the deep-penetration seismic data obtained on these cruises. Only EEZ-SCAN 84 data were used for the map compilations because available data from other cruises in this region are sparsely located, have poor navigational control, or were obtained with seismic systems that were not powerful enough to resolve oceanic basement. For this map series, sediment thickness and depth to basement were determined only in the deep-ocean basin regions because the seismic system used on the EEZ-SCAN 84 cruises could not resolve oceanic basement beneath the thick sediments of the continental slope. All the data used to compile the maps are presented in the "Atlas of the Exclusive Economic Zone, Western Conterminous United States" (EEZ-SCAN 84 Scientific Staff, 1986). Basement Outcrops GLORIA imagery was used to locate areas of basement outcrop throughout the region. Where possible, sediment thickness on and immediately adjacent to basement outcrops was measured from seismic data. Where there was no bathymetric or seismic control, a seamount peak was assumed to have no sediment cover. A pattern is used on the map to indicate all basement outcrops. Data Reduction Acoustic basement in the basins, invariably oceanic Layer 2, was observed on all of the seismic records. One-way traveltime was measured from the sea floor to acoustic basement. Because the trackline spacing of about 30 km is relatively large compared to the data density along track, we chose to measure the sediment thickness every 0.5 hour or at an interval of approximately 7.5 km. Water depth was measured with a 10-kHz profiler. Depth to basement was calculated using the sea surface as the zero datum and adding the corrected water depth (Carter, 1980) to the sediment thickness. Acoustic travel times were converted to depths by first calculating a regression equation from the interval velocity versus depth data of Connard and others (1984). Their data base comprises a compilation of all available Deep Sea Drilling Project data plus wide-angle refraction data, which were collected in Cascadia Basin west of Oregon and represents the best data set available for the United States west coast EEZ. The regression equation was integrated to determine sediment thickness as a function of one-way traveltime . The resulting equation is z = 1400t + 0 .5t 2 where z is sediment thickness in meters, and t is one-way traveltime in seconds. Sediment thicknesses calculated using this equation were compared to values calculated from the general equation of Carlson and others (1986). Values for sediment thickness calculated by the two equations differed by no greater than 10 percent throughout the range of travel times. Bathymetry The bathymetry is from Chase and others (1981). The bathymetric data were compiled from a variety of sources, and data quality is inconsistent. Because of differences in navigational precision and density of coverage, the bathymetric contours of a feature may be at a different location than the corresponding isopleths derived from the EEZ-SCAN 84 data, or a feature may not be indicated on the bathymetry at all. These situations occur because either the feature is poorly located in the bathymetric data set or, especially in the outer EEZ, the bathymetric data are too sparse to have defined the existence of a feature. Acknowledgments Topographic digital data bases were corrected and verified by Christina Lief. Gerald Evenden developed the computer software system MAPGEN, used to compose this map. Reviews, suggestions, and technical contributions from Edward C. Escowitz and Florence Wong and advice about cartographic design from Will Stettner substantially improved the quality of this map. References Cited Carlson, R.L., Gangi, A.F., and Snow, K.R., 1986, Empirical reflection-traveltime/ depth and velocity/depth functions for the deep-sea sediment column: Journal of Geophysical Research, v. 91, no. B8, p. 8249-8266. Carter, D.J.T., 1980, Echo-sounding correction tables: Taunton, United Kingdom, Hydrographic Department, Ministry of Defence, 150 p. Chase, T.E., Wilde, Pat, Normark, W.R, Miller, C.P., Seekins, B.A., and Young, J.D., 1981, Offshore topography of the Western United States between 32° and 49° North latitudes: U.S. Geological Survey Open-File Report 81-443, scale 1:864,518 at 38° latitude, 2 sheets. Connard, G., Couch, R., Keeling , K., Roy, J., and Troseth, S., 1984, Abyssal plain and continental net-objective sedimentary thicknesses, in Kulm, L.D., and others, eds., Western North America continental margin and adjacent ocean floor off Oregon and Washington, Atlas 1 of Regional Atlas Series, Ocean Margin Drilling Program: Woods Hole, Mass., Marine Science International, sheet 7. EEZ-SCAN 84 Scientific Staff, 1986, Atlas of the Exclusive Economic Zone, Western Conterminous United States: U.S. Geological Survey Miscellaneous Investigations Series I-1792, scale 1:500,000, 152 p. See Also "U.S. Pacific West Coast Field Activities" (Paskevich and others, 2011; http://pubs.usgs.gov/of/2010/1332/htmldocs/pc/pc_overview.html). Paskevich, V.F., Wong, F.L., O?Malley, J.J., Stevenson, A.J., and Gutmacher, C.E., 2011, GLORIA sidescan-sonar imagery for parts of the U.S. Exclusive Economic Zone and adjacent areas: U.S. Geological Survey Open-File Report 2010?1332, available at http://pubs.usgs.gov/of/2010/1332/.

IMAP↗

USGS1993

Map showing depth to basement in the deep-sea basins of the Pacific continental margin, Cape Mendocino to Point Conception

The U.S. Geological Survey conducted a series of cruises, EEZSCAN 84 (EEZ-SCAN 84 Scientific Staff, 1986), to collect reconnaissance data on the newly proclaimed Exclusive Economic Zone (EEZ), the area out to 200 nautical miles from the coastline of the United States. The cruises systematically surveyed the entire conterminous United States west coast EEZ using the Geological Long-Range Inclined Asdic (GLORIA) side-scan sonar, a 160-in 3 airgun seismic-reflection profiler, a 3.5-kHz high-resolution seismic-reflection profiler, a 10-kHz echo sounder, and a proton-precession magnetometer. The nominal trackline spacing throughout the survey was 30 km. Derivative maps of sediment thickness (I-2089-A, I-2090-A, I-2091-A) and depth to basement (I-2089-B, I-2090-B, I-2091-B) in the basins of the west coast EEZ were compiled from both the sonar-image dala and the deep-penetration seismic data obtained on these cruises. Only EEZ-SCAN 84 data were used for the map compilations because available data from other cruises in this region are sparsely located, have poor navigational control, or were obtained with seismic systems that were not powerful enough to resolve oceanic basement. For this map series, sediment thickness and depth to basement were determined only in the deep-ocean basin regions because the seismic system used on the EEZ-SCAN 84 cruises could not resolve oceanic basement beneath the thick sediments of the continental slope. All the data used to compile the maps are presented in the "Atlas of the Exclusive Economic Zone, Western Conterminous United States" (EEZ-SCAN 84 Scientific Staff, 1986). Basement Outcrops GLORIA imagery was used to locate areas of basement outcrop throughout the region. Where possible, sediment thickness on and immediately adjacent to basement outcrops was measured from seismic data. Where there was no bathymetric or seismic control, a seamount peak was assumed to have no sediment cover. A pattern is used on the map to indicate all basement outcrops. Data Reduction Acoustic basement in the basins, invariably oceanic Layer 2, was observed on all of the seismic records. One-way traveltime was measured from the sea floor to acoustic basement. Because the trackline spacing of about 30 km is relatively large compared to the data density along track, we chose to measure the sediment thickness every 0.5 hour or at an interval of approximately 7.5 km. Water depth was measured with a 10-kHz profiler. Depth to basement was calculated using the sea surface as the zero datum and adding the corrected water depth (Carter, 1980) to the sediment thickness. Acoustic travel times were converted to depths by first calculating a regression equation from the interval velocity versus depth data of Connard and others (1984). Their data base comprises a compilation of all available Deep Sea Drilling Project data plus wide-angle refraction data, which were collected in Cascadia Basin west of Oregon and represents the best data set available for the United States west coast EEZ. The regression equation was integrated to determine sediment thickness as a function of one-way traveltime . The resulting equation is z = 1400t + 0 .5t 2 where z is sediment thickness in meters, and t is one-way traveltime in seconds. Sediment thicknesses calculated using this equation were compared to values calculated from the general equation of Carlson and others (1986). Values for sediment thickness calculated by the two equations differed by no greater than 10 percent throughout the range of travel times. Bathymetry The bathymetry is from Chase and others (1981). The bathymetric data were compiled from a variety of sources, and data quality is inconsistent. Because of differences in navigational precision and density of coverage, the bathymetric contours of a feature may be at a different location than the corresponding isopleths derived from the EEZ-SCAN 84 data, or a feature may not be indicated on the bathymetry at all. These situations occur because either the feature is poorly located in the bathymetric data set or, especially in the outer EEZ, the bathymetric data are too sparse to have defined the existence of a feature. Acknowledgments Topographic digital data bases were corrected and verified by Christina Lief. Gerald Evenden developed the computer software system MAPGEN, used to compose this map. Reviews, suggestions, and technical contributions from Edward C. Escowitz and Florence Wong and advice about cartographic design from Will Stettner substantially improved the quality of this map. References Cited Carlson, R.L., Gangi, A.F., and Snow, K.R., 1986, Empirical reflection-traveltime/ depth and velocity/depth functions for the deep-sea sediment column: Journal of Geophysical Research, v. 91, no. B8, p. 8249-8266. Carter, D.J.T., 1980, Echo-sounding correction tables: Taunton, United Kingdom, Hydrographic Department, Ministry of Defence, 150 p. Chase, T.E., Wilde, Pat, Normark, W.R, Miller, C.P., Seekins, B.A., and Young, J.D., 1981, Offshore topography of the Western United States between 32° and 49° North latitudes: U.S. Geological Survey Open-File Report 81-443, scale 1:864,518 at 38° latitude, 2 sheets. Connard, G., Couch, R., Keeling , K., Roy, J., and Troseth, S., 1984, Abyssal plain and continental net-objective sedimentary thicknesses, in Kulm, L.D., and others, eds., Western North America continental margin and adjacent ocean floor off Oregon and Washington, Atlas 1 of Regional Atlas Series, Ocean Margin Drilling Program: Woods Hole, Mass., Marine Science International, sheet 7. EEZ-SCAN 84 Scientific Staff, 1986, Atlas of the Exclusive Economic Zone, Western Conterminous United States: U.S. Geological Survey Miscellaneous Investigations Series I-1792, scale 1:500,000, 152 p. See Also "U.S. Pacific West Coast Field Activities" (Paskevich and others, 2011; http://pubs.usgs.gov/of/2010/1332/htmldocs/pc/pc_overview.html). Paskevich, V.F., Wong, F.L., O?Malley, J.J., Stevenson, A.J., and Gutmacher, C.E., 2011, GLORIA sidescan-sonar imagery for parts of the U.S. Exclusive Economic Zone and adjacent areas: U.S. Geological Survey Open-File Report 2010?1332, available at http://pubs.usgs.gov/of/2010/1332/.

IMAP↗

USGS1993

Map showing sediment isopachs in the deep-sea basins of the Pacific Continental Margin, Strait of Juan de Fuca to Cape Mendocino

The U.S. Geological Survey conducted a series of cruises, EEZSCAN 84 (EEZ-SCAN 84 Scientific Staff, 1986), to collect reconnaissance data on the newly proclaimed Exclusive Economic Zone (EEZ), the area out to 200 nautical miles from the coastline of the United States. The cruises systematically surveyed the entire conterminous United States west coast EEZ using the Geological Long-Range Inclined Asdic (GLORIA) side-scan sonar, a 160-in 3 airgun seismic-reflection profiler, a 3.5-kHz high-resolution seismic-reflection profiler, a 10-kHz echo sounder, and a proton-precession magnetometer. The nominal trackline spacing throughout the survey was 30 km. Derivative maps of sediment thickness (I-2089-A, I-2090-A, I-2091-A) and depth to basement (I-2089-B, I-2090-B, I-2091-B) in the basins of the west coast EEZ were compiled from both the sonar-image dala and the deep-penetration seismic data obtained on these cruises. Only EEZ-SCAN 84 data were used for the map compilations because available data from other cruises in this region are sparsely located, have poor navigational control, or were obtained with seismic systems that were not powerful enough to resolve oceanic basement. For this map series, sediment thickness and depth to basement were determined only in the deep-ocean basin regions because the seismic system used on the EEZ-SCAN 84 cruises could not resolve oceanic basement beneath the thick sediments of the continental slope. All the data used to compile the maps are presented in the "Atlas of the Exclusive Economic Zone, Western Conterminous United States" (EEZ-SCAN 84 Scientific Staff, 1986). Basement Outcrops GLORIA imagery was used to locate areas of basement outcrop throughout the region. Where possible, sediment thickness on and immediately adjacent to basement outcrops was measured from seismic data. Where there was no bathymetric or seismic control, a seamount peak was assumed to have no sediment cover. A pattern is used on the map to indicate all basement outcrops. Data Reduction Acoustic basement in the basins, invariably oceanic Layer 2, was observed on all of the seismic records. One-way traveltime was measured from the sea floor to acoustic basement. Because the trackline spacing of about 30 km is relatively large compared to the data density along track, we chose to measure the sediment thickness every 0.5 hour or at an interval of approximately 7.5 km. Water depth was measured with a 10-kHz profiler. Depth to basement was calculated using the sea surface as the zero datum and adding the corrected water depth (Carter, 1980) to the sediment thickness. Acoustic travel times were converted to depths by first calculating a regression equation from the interval velocity versus depth data of Connard and others (1984). Their data base comprises a compilation of all available Deep Sea Drilling Project data plus wide-angle refraction data, which were collected in Cascadia Basin west of Oregon and represents the best data set available for the United States west coast EEZ. The regression equation was integrated to determine sediment thickness as a function of one-way traveltime . The resulting equation is z = 1400t + 0 .5t 2 where z is sediment thickness in meters, and t is one-way traveltime in seconds. Sediment thicknesses calculated using this equation were compared to values calculated from the general equation of Carlson and others (1986). Values for sediment thickness calculated by the two equations differed by no greater than 10 percent throughout the range of travel times. Bathymetry The bathymetry is from Chase and others (1981). The bathymetric data were compiled from a variety of sources, and data quality is inconsistent. Because of differences in navigational precision and density of coverage, the bathymetric contours of a feature may be at a different location than the corresponding isopleths derived from the EEZ-SCAN 84 data, or a feature may not be indicated on the bathymetry at all. These situations occur because either the feature is poorly located in the bathymetric data set or, especially in the outer EEZ, the bathymetric data are too sparse to have defined the existence of a feature. Acknowledgments Topographic digital data bases were corrected and verified by Christina Lief. Gerald Evenden developed the computer software system MAPGEN, used to compose this map. Reviews, suggestions, and technical contributions from Edward C. Escowitz and Florence Wong and advice about cartographic design from Will Stettner substantially improved the quality of this map. References Cited Carlson, R.L., Gangi, A.F., and Snow, K.R., 1986, Empirical reflection-traveltime/ depth and velocity/depth functions for the deep-sea sediment column: Journal of Geophysical Research, v. 91, no. B8, p. 8249-8266. Carter, D.J.T., 1980, Echo-sounding correction tables: Taunton, United Kingdom, Hydrographic Department, Ministry of Defence, 150 p. Chase, T.E., Wilde, Pat, Normark, W.R, Miller, C.P., Seekins, B.A., and Young, J.D., 1981, Offshore topography of the Western United States between 32° and 49° North latitudes: U.S. Geological Survey Open-File Report 81-443, scale 1:864,518 at 38° latitude, 2 sheets. Connard, G., Couch, R., Keeling , K., Roy, J., and Troseth, S., 1984, Abyssal plain and continental net-objective sedimentary thicknesses, in Kulm, L.D., and others, eds., Western North America continental margin and adjacent ocean floor off Oregon and Washington, Atlas 1 of Regional Atlas Series, Ocean Margin Drilling Program: Woods Hole, Mass., Marine Science International, sheet 7. EEZ-SCAN 84 Scientific Staff, 1986, Atlas of the Exclusive Economic Zone, Western Conterminous United States: U.S. Geological Survey Miscellaneous Investigations Series I-1792, scale 1:500,000, 152 p. See Also "U.S. Pacific West Coast Field Activities" (Paskevich and others, 2011; http://pubs.usgs.gov/of/2010/1332/htmldocs/pc/pc_overview.html). Paskevich, V.F., Wong, F.L., O?Malley, J.J., Stevenson, A.J., and Gutmacher, C.E., 2011, GLORIA sidescan-sonar imagery for parts of the U.S. Exclusive Economic Zone and adjacent areas: U.S. Geological Survey Open-File Report 2010?1332, available at http://pubs.usgs.gov/of/2010/1332/.

IMAP↗

USGS1993

Map showing depth to basement in the deep-sea basins of the Pacific continental margin, Strait of Juan de Fuca to Cape Mendocino

The U.S. Geological Survey conducted a series of cruises, EEZSCAN 84 (EEZ-SCAN 84 Scientific Staff, 1986), to collect reconnaissance data on the newly proclaimed Exclusive Economic Zone (EEZ), the area out to 200 nautical miles from the coastline of the United States. The cruises systematically surveyed the entire conterminous United States west coast EEZ using the Geological Long-Range Inclined Asdic (GLORIA) side-scan sonar, a 160-in 3 airgun seismic-reflection profiler, a 3.5-kHz high-resolution seismic-reflection profiler, a 10-kHz echo sounder, and a proton-precession magnetometer. The nominal trackline spacing throughout the survey was 30 km. Derivative maps of sediment thickness (I-2089-A, I-2090-A, I-2091-A) and depth to basement (I-2089-B, I-2090-B, I-2091-B) in the basins of the west coast EEZ were compiled from both the sonar-image dala and the deep-penetration seismic data obtained on these cruises. Only EEZ-SCAN 84 data were used for the map compilations because available data from other cruises in this region are sparsely located, have poor navigational control, or were obtained with seismic systems that were not powerful enough to resolve oceanic basement. For this map series, sediment thickness and depth to basement were determined only in the deep-ocean basin regions because the seismic system used on the EEZ-SCAN 84 cruises could not resolve oceanic basement beneath the thick sediments of the continental slope. All the data used to compile the maps are presented in the "Atlas of the Exclusive Economic Zone, Western Conterminous United States" (EEZ-SCAN 84 Scientific Staff, 1986). Basement Outcrops GLORIA imagery was used to locate areas of basement outcrop throughout the region. Where possible, sediment thickness on and immediately adjacent to basement outcrops was measured from seismic data. Where there was no bathymetric or seismic control, a seamount peak was assumed to have no sediment cover. A pattern is used on the map to indicate all basement outcrops. Data Reduction Acoustic basement in the basins, invariably oceanic Layer 2, was observed on all of the seismic records. One-way traveltime was measured from the sea floor to acoustic basement. Because the trackline spacing of about 30 km is relatively large compared to the data density along track, we chose to measure the sediment thickness every 0.5 hour or at an interval of approximately 7.5 km. Water depth was measured with a 10-kHz profiler. Depth to basement was calculated using the sea surface as the zero datum and adding the corrected water depth (Carter, 1980) to the sediment thickness. Acoustic travel times were converted to depths by first calculating a regression equation from the interval velocity versus depth data of Connard and others (1984). Their data base comprises a compilation of all available Deep Sea Drilling Project data plus wide-angle refraction data, which were collected in Cascadia Basin west of Oregon and represents the best data set available for the United States west coast EEZ. The regression equation was integrated to determine sediment thickness as a function of one-way traveltime . The resulting equation is z = 1400t + 0 .5t 2 where z is sediment thickness in meters, and t is one-way traveltime in seconds. Sediment thicknesses calculated using this equation were compared to values calculated from the general equation of Carlson and others (1986). Values for sediment thickness calculated by the two equations differed by no greater than 10 percent throughout the range of travel times. Bathymetry The bathymetry is from Chase and others (1981). The bathymetric data were compiled from a variety of sources, and data quality is inconsistent. Because of differences in navigational precision and density of coverage, the bathymetric contours of a feature may be at a different location than the corresponding isopleths derived from the EEZ-SCAN 84 data, or a feature may not be indicated on the bathymetry at all. These situations occur because either the feature is poorly located in the bathymetric data set or, especially in the outer EEZ, the bathymetric data are too sparse to have defined the existence of a feature. Acknowledgments Topographic digital data bases were corrected and verified by Christina Lief. Gerald Evenden developed the computer software system MAPGEN, used to compose this map. Reviews, suggestions, and technical contributions from Edward C. Escowitz and Florence Wong and advice about cartographic design from Will Stettner substantially improved the quality of this map. References Cited Carlson, R.L., Gangi, A.F., and Snow, K.R., 1986, Empirical reflection-traveltime/ depth and velocity/depth functions for the deep-sea sediment column: Journal of Geophysical Research, v. 91, no. B8, p. 8249-8266. Carter, D.J.T., 1980, Echo-sounding correction tables: Taunton, United Kingdom, Hydrographic Department, Ministry of Defence, 150 p. Chase, T.E., Wilde, Pat, Normark, W.R, Miller, C.P., Seekins, B.A., and Young, J.D., 1981, Offshore topography of the Western United States between 32° and 49° North latitudes: U.S. Geological Survey Open-File Report 81-443, scale 1:864,518 at 38° latitude, 2 sheets. Connard, G., Couch, R., Keeling , K., Roy, J., and Troseth, S., 1984, Abyssal plain and continental net-objective sedimentary thicknesses, in Kulm, L.D., and others, eds., Western North America continental margin and adjacent ocean floor off Oregon and Washington, Atlas 1 of Regional Atlas Series, Ocean Margin Drilling Program: Woods Hole, Mass., Marine Science International, sheet 7. EEZ-SCAN 84 Scientific Staff, 1986, Atlas of the Exclusive Economic Zone, Western Conterminous United States: U.S. Geological Survey Miscellaneous Investigations Series I-1792, scale 1:500,000, 152 p. See Also "U.S. Pacific West Coast Field Activities" (Paskevich and others, 2011; http://pubs.usgs.gov/of/2010/1332/htmldocs/pc/pc_overview.html). Paskevich, V.F., Wong, F.L., O?Malley, J.J., Stevenson, A.J., and Gutmacher, C.E., 2011, GLORIA sidescan-sonar imagery for parts of the U.S. Exclusive Economic Zone and adjacent areas: U.S. Geological Survey Open-File Report 2010?1332, available at http://pubs.usgs.gov/of/2010/1332/.

IMAP↗

USGS1992

Toward digital geologic map standards: a progress report

Establishing modern scientific and technical standards for geologic maps and their derivative map products is vital to both producers and users of such maps as we move into an age of digital cartography. Application of earth-science data in complex geographic information systems, acceleration of geologic map production, and reduction of population costs require that national standards be developed for digital geologic cartography and computer analysis. Since December 1988, under commission of the Chief Geologic of the U.S. Geological Survey and the mandate of the National Geologic Mapping Program (with added representation from the Association of American State Geologists), a committee has been designing a comprehensive set of scientific map standards. Three primary issues were: (1) selecting scientific symbology and its digital representation; (2) creating an appropriate digital coding system that characterizes geologic features with respect to their physical properties, stratigraphic and structural relations, spatial orientation, and interpreted mode of origin; and (3) developing mechanisms for reporting levels of certainty for descriptive as well as measured properties. Approximately 650 symbols for geoscience maps, including present usage of the U.S Geological Survey, state geological surveys, industry, and academia have been identified and tentatively adopted. A proposed coding system comprises four-character groupings of major and minor codes that can identify all attributes of a geologic feature. Such a coding system allows unique identification of as many as 105 geologic names and values on a given map. The new standard will track closely the latest developments of the Proposed Standard for Digital Cartographic Data soon to be submitted to the National Institute of Standards and Technology by the Federal Interagency Coordinating Committee on Digital Cartography. This standard will adhere generally to the accepted definitions and specifications for spatial data transfer. It will require separate specifications of digital cartographic quality relating to positional accuracy and ranges of measured and interpreted values such as geologic age and rock composition. Provisional digital geologic map standards will be published for trial implementation. After approximately two years, when comments on the proposed standards have been solicited and modifications made, formal adoption of the standards will be recommended. Widespread acceptance of the new standards will depend on their applicability to the broadest range of earth-science map products and their adaptability to changing cartographic technology.

Conference Paper↗

USGS1981

Growth and mortality of fry of Lake Michigan lake trout during chronic exposure to PCB's and DDE

Fry hatched from eggs of Lake Michigan lake trout (Salvelinus namaycush) were exposed (beginning about 1 week after hatching) to contaminant concentrations of PCB's and DDE similar to those in water and plankton in southeastern Lake Michigan (1X level), and to concentrations about 5 (5X) and 25 (25X) times greater. Body concentrations of contaminants in fry (I?g/g) decreased at 1X levels of PCB's and at 1X and 5X levels of DDE, but generally increased at all other contaminant exposure levels. Uptake of PCB's and DDE was evident from increases in body burden (I?g/fish) of the contaminants at all exposure levels and the controls. Growth was not significantly affected by any of the contaminant exposures. Mortalities of fry exposed to the lower concentrations (1X and 5X) were significantly less than those of control fry before day 56; however, between days 57 and 136, mortality rates increased dramatically and were significantly higher in all nine exposed groups than in the control group. For the last 40-day period (days 137-176), mortality was low and leveled off, but continued to be significantly higher in all exposed fry (except those in 1X and 5X PCB's) than in control fry. By the end of the 176-day study, the total cumulative mortality ranged from 30.5 to 46.5% in the exposed groups and was 21.7% in the control group.

Technical Paper↗

USGS2016

Regional water table (2014) in the Mojave River and Morongo Groundwater Basins, southwestern Mojave Desert, California

Data for static water-levels measured in about 610 wells during March-April 2014 by the U.S. Geological Survey (USGS), the Mojave Water Agency (MWA) , and other local water districts were compiled to construct a regional water-table map . This map shows the elevation of the water table and general direction of groundwater movement in and around the Mojave River and Morongo groundwater basins. Water-level measurements recorded by the USGS and MWA staff were measured and compiled according to the procedures described in the Groundwater Technical Procedures of the U.S. Geological Survey ( Cunningham and Schalk, 2011 ). Water-level data submitted by cooperating local water districts were collected by using procedures established by the corresponding agency, and compiled according to the procedures described in the Groundwater Technical Procedures of the U.S. Geological Survey ( Cunningham and Schalk, 2011 ). All data were compared to historical data for quality-assurance purposes. Water-level contours from the 2012 water-level map ( Teague and others, 2014 ) were used as a guide to interpret and shape the 2014 water-level contours in areas where 2014 water-level data were not available; these contours are shown as dashed (approximate) on the water-table map. In addition to being available on the interactive map , 2014 water-level data and contours are shown for the entire area of the Mojave River and Morongo groundwater basins on Plate 1 . Water-level data for 2014 are accessible through the website by clicking the 2014 Sites button on the Data Downloads page .

California↗

USGS2007

Southern California Bight 2003 Regional Monitoring Program: V. water quality

More than $30 million is expended annually on environmental monitoring in the Southern California Bight (SCB), yet only 5% of the Bight is monitored on an ongoing basis. Therefore, environmental managers in the SCB decided to expand their monitoring program and, starting in 1994, decided to conduct periodic regional assessments of ecosystem condition and assess the overall health of the SCB. Sixty-five different organizations collaborated in 2003 to create the third SCB Regional Monitoring Program (Bight '03). Bight '03 was designed to be integrated regional monitoring program that encompasses regulatory, academic, and non-governmental agencies. Bight '03 had three components: Coastal Ecology, Shoreline Microbiology, and Water Quality. This report addresses the purpose, approach, findings, and recommendations from the Water Quality component, which focused on contamination-laden stormwater runoff, in particularly its variability in time and space as well as its short-term ecological impacts. Specifically, the Bight '03 Water Quality component had three primary goals, the first of which was to described the temporal evolution of stormwater plumes produced by the major southern California rivers. Specifically, the study was intended to determine how far offshore the plumes extended, how rapidly they advected, how long before the plumes dispersed and how these properties differed among storms and river systems. The second goal was to describe how the physical properties (e.g., turbidity, temperature, salinity) of the plume related to biogeochemical and ecological properties that are of more direct concern to the water quality management community. Accomplished primarily through ship-based sampling of water quality parameters, this second goal was to describe how far offshore, and for how ;long after the storm, elevated bacterial concentrations, toxicity, and nutrients could be detected. Similar to the fist goal, the study also addressed how these answers differed among storms and river systems. The final goal was to determine whether relationships between environmental indicators derived from coincident satellite remote sensing and in situ data sets are sufficiently robust for remote sensing to become a routine water quality monitoring programs. Remote sensing data potentially provide coastal managers with synoptic near-real time regional information about prevailing ocean conditions and hazards that would complement existing field-based sampling protocols, but only if there is a thorough understanding of how to interpret and utilize the proxy measures, such as ocean color. The understanding of these priorities through Bight '03 sampling is intended to provide the basis for developing more efficient, widespread and coast-effective coastal ocean monitoring techniques. Water quality data were collected across eight major river systems within four geographic regions of southern California. Field measurements included the primary contaminants of interest, i.e., bacterial concentrations, water toxicity, and nutrients, as well as related parameters such as temperatures, salinity, total suspended solids, transmissivity, chlorophyll, and colored dissolved organic material (CDOM) concentrations. For each of the four major regions, i.e., Santa Clara/Ventura Rivers, Ballona Creek/Santa Monica Bay, San Pedro Shelf, and the San Diego, Tijuana Rivers, two stormwater events were sampled for up to three days by ship resulting in 574 water column CTD+ profiles and 705 discrete water samples during 36 ship-days. These data were analyzed in combination with MODIS ocean color satellite remote sensing, buoy meteorological observations, drifters, and HF radar current measurements to evaluate the dispersal patterns, dynamics, and impacts of the freshwater runoff plumes. Based on these data and resulting analyses, the principal conclusions were as follow: - Stormwater runoff turbidity plumes were found to be spatially extensive, covering up to 2500 km 2 within the Southern California Bight nearshore zone, and persisting over the entire duration of the post-storm sampling period (at least 3 days). - The spatial and temporal extent of the portion of the plume with contaminants was far less than that of the turbidity plume, typically representing <10% of its area (30-70% off Tijuana); however, with contaminant impacts generally greatly reduced or absent by the third or fourth day of sampling - Pseudo-nitzschia , a harmful algae that produces domoic acid, was found to be more abundant than previously reported. - Accurately describing stormwater runoff plumes requires a combination of in situ and remote sensing assessment tools, with satellite data providing valuable synoptic information. From these conclusions, the following recommendations are provided: - Future studies designed to describe stormwater plumes should include a combination of ship - and remote sensing-based methods. - CDOM is a good proxy of the freshwater runoff plume and should be added as a standard measurement parameter on water quality instrument packages. - Investigations are needed that assess on a local basis the spatial extent of ecological effects of stormwater plumes early in the storm, ideally accompanied by airborne imagery to provide improved temporal & spatial resolution, to fill in knowledge gaps. The next Bight regional monitoring program should focus on quantifying nutrient loadings and dynamics in association with stormwater runoff and other sources, and characterize their attendant ecosystem impacts such as phytoplankton blooms.

California↗

USGS2018

General introduction for the “National Field Manual for the Collection of Water-Quality Data”

Background As part of its mission, the U.S. Geological Survey (USGS) collects data to assess the quality of our Nation’s water resources. A high degree of reliability and standardization of these data are paramount to fulfilling this mission. Documentation of nationally accepted methods used by USGS personnel serves to maintain consistency and technical quality in data-collection activities. “The National Field Manual for the Collection of Water-Quality Data” (NFM) provides documented guidelines and protocols for USGS field personnel who collect water-quality data. The NFM provides detailed, comprehensive, and citable procedures for monitoring the quality of surface water and groundwater. Topics in the NFM include (1) methods and protocols for sampling water resources, (2) methods for processing samples for analysis of water quality, (3) methods for measuring field parameters, and (4) specialized procedures, such as sampling water for low levels of mercury and organic wastewater chemicals, measuring biological indicators, and sampling bottom sediment for chemistry. Personnel who collect water-quality data for national USGS programs and projects, including projects supported by USGS cooperative programs, are mandated to use protocols provided in the NFM per USGS Office of Water Quality Technical Memorandum 2002.13. Formal training, for example, as provided in the USGS class, “Field Water-Quality Methods for Groundwater and Surface Water,” and field apprenticeships supplement the guidance provided in the NFM and ensure that the data collected are high quality, accurate, and scientifically defensible.

Techniques and Methods↗

USGS1975

Use of USGS earth science products by city planning agencies in the San Francisco Bay region, California

An inventory of the use of USGS products in selected planning studies, plans, plan implementation devices, and other planning-related activities was completed for the ninety-one cities in the nine-county San Francisco Bay region. This inventory was designed to determine and document the use of the 85 earth science products prepared as a part of the San Francisco Bay Region Environment and Resources Planning Study (SFBRS). This inventory showed that: (1) three-fourths of the cities had planning staffs who were familiar with SFBRS products, or had made use of such products; (2) over half of the cities had prepared planning documents which contained references to SFBRS products; (3) the types of planning applications most often indicated were: geologic hazards studies; seismic safety, public safety, conservation, and open-space plan elements; general reference; and the preparation and review of environmental impact reports and statements; (4) almost 90 percent of all 85 SFBRS products were used at least once for a city planning activity, and one product was used at least 67 times for various city planning activities; and (5) at least forty-five other other USGS products were also used for various city planning activities. All of the seven SFBRS products that were used 30 or more times for city planning activities were small-scale, large-areal-coverage, hazard-type products. Each product is interpretative and contains additional data which makes it more relevant or more interesting. The planning staffs of each city were also interviewed and asked to indicate any problems in the use of the SFBRS products, to recommend improvements, and to identify any needed or desired earth science data. The responses showed that: (1) the map scales commonly used by cities were much larger than 1:12,000; (2) few cities had planning staffs with training or experience in the earth sciences or engineering; (3) less than one-fourth of the cities failed to use SFBRS products-primarily because their staffs were unaware of the SFBRS, unfamiliar with its products, or lacked adequate capability; (4) almost two-thirds of the cities expressed some problems in using the products-primarily scale and detail; (5) over two-thirds of the cities expressed an interest in continuing to use, or planning to use, the SFBRS products in the future, and a need or desire for additional earth science, engineering or other data; and (6) over one-half of the cities suggested improvements-primarily larger scale or more detail and less technical or more interpretative products. From the inventory and responses to the interviews, it is concluded that the cities in the Bay region have considerable familiarity with, and have made substantial use of, SFBRS products. This use was made by many cities despite their small size, limited staff capability, and the design of the products which was intended primarily for regional planning at a regional scale. Suggestions are made to ensure more familiarity with, and more effective use of, earth science data in the future. These suggestions include: (1) providing engineering interpretations and land-use capability ratings to make earth science data more readily usable; (2) monitoring and analyzing new state laws and regulations to better anticipate and respond to local earth science data needs; (3) including technical assistance with any earth science data designed for planners and decision-makers; (4) providing larger scale and greater detail earth science data on a demonstration basis; (5) giving priority to urban and urbanizing areas so as to conserve limited staff resources; and (6) ensuring product distribution to all potential users.

California↗

USGS2010

2009 Observer Survey Report

The USA‐National Phenology Network (USA‐NPN) seeks to engage volunteer observers in collecting phenological observations of plants and animals using consistent standards and to contribute their observations to a national data repository. In March 2009, the National Coordinating Office staff implemented an online monitoring program for 213 plant species. In this pilot year of the program, 547 observers reported phenology observations on one or more plants via the online interface. To learn more about our participants and to improve our program and our participants’ experience, we undertook a survey of individuals registered in the USA‐NPN phenology observation program. This report summarizes the results of the 2009 observer surveys. Two populations were targeted via separate surveys: Individuals who registered with the USA‐NPN plant phenology monitoring program via MyNPN but did not submit any data in 2009 (hereafter termed “non‐reporting participants”), and Individuals who submitted phenology observations via MyNPN in 2009 (hereafter termed “reporting participants”). In general, all participants in the 2009 USA‐NPN plant phenology observation program seemed to have a generally good experience. When asked why they would or would not recommend the program to friends, the majority of comments were of a positive nature, and included explanations such as, “It is an interesting and fairly light duty activity”, “It’s a cool program!”, and “A way to contribute to science”. The most commonly indicated reason for not submitting observations among non‐reporters was getting lost in the registration process (14% of respondents). Another 14% of respondents indicated that they had collected observations but did not submit them online, indicating that more people may be engaged in understanding phenology than our estimates based on data submitted suggest. Survey participants’ suggestions for improving the program fell into several categories, including the need for a more expansive list of plants from which to pick, the ability to monitor animals, and more information on the plants, including photographs of the various phenophases to aid in identification. Participants also requested increased contact from the USA‐NPN, in the form of weekly or monthly emails or newsletters and reminders to collect and submit observations. Many of these suggestions are either already being addressed in changes being made to the monitoring system and online entry system or are planned for the future.

USA-NPN Technical Series↗

USGS1998

U.S. Geological Survey cooperative water-resources programs in Chester County, Pennsylvania

Since 1969, the U.S. Geological Survey (USGS) has had a cooperative water-resources investigation program with Chester County to measure and describe the water resources of the County. Generally, the USGS provides one-half of the program funding, and local cooperators are required to provide matching funds. Cooperation has been primarily with the Chester County Water Resources Authority (CCWRA), with participation from the Chester County Health Department and funding from the Chester County Board of Commissioners. Municipalities and the Red Clay Valley Association also have provided part of the funding for several projects. This report describes how the long-term partnership between the USGS and Chester County, Pa., provides the County with the information that it needs for sound water-resources management. The CCWRA was created in 1961, primarily for land acquisition and planning for flood-control and water-supply projects. With the backing of the Brandywine Valley Association, the CCWRA started its first cooperative project with the USGS in 1969. It was a study of the water-quality condition of Chester County streams with an emphasis on benthic macroinvertebrates and stream chemistry. The kinds of projects and data collection conducted by the USGS have changed with the needs of Chester County and the mission of the CCWRA. Chester County is experiencing rapid population growth (it had the tenth-highest rate of growth in the nation from 1980 to 1990). This growth places considerable stress on water resources and has caused the CCWRA to broaden its focus from flood control to water-supply planning, water quality, and ground-water and surface-water management. The results of USGS studies are used by the CCWRA and other County agencies, including the Planning Commission, Health Department, and Parks and Recreation Department, for conducting day-to-day activities and planning for future growth. The results also are used by the CCWRA to provide guidance and technical assistance to municipalities, water suppliers, industrial dischargers, watershed and conservancy associations and other civic organizations, state and Federal agencies, river basin commissions, and the private sector. The cooperative water-resources program, which is described in the following sections, benefits not only the citizens of Chester County but also serves the interests of the Federal Government. Innovative studies conducted in Chester County provide methods and interpretations that often can be used nationwide, and the headwaters of several interstate drainages lie within the County. Major program thrusts include collection of surface-water, ground-water, and water-quality data and interpretive studies. The use of this information also is described.

Pennsylvania↗

USGS1988

Methods for delineating flood-prone areas in the Great Basin of Nevada and adjacent states

The Great Basin is a region of about 210,000 square miles having no surface drainage to the ocean; it includes most of Nevada and parts of Utah, California, Oregon, Idaho, and Wyoming. The area is characterized by many parallel mountain ranges and valleys trending north-south. Stream channels usually are well defined and steep within the mountains, but on reaching the alluvial fan at the canyon mouth, they may diverge into numerous distributary channels, be discontinuous near the apex of the fan, or be deeply entrenched in the alluvial deposits. Larger rivers normally have well-defined channels to or across the valley floors, but all terminate at lakes or playas. Major floods occur in most parts of the Great Basin and result from snowmelt, frontal-storm rainfall, and localized convective rainfall. Snowmelt floods typically occur during April-June. Floods resulting from frontal rain and frontal rain on snow generally occur during November-March. Floods resulting from convective-type rainfall during localized thunderstorms occur most commonly during the summer months. Methods for delineating flood-prone areas are grouped into five general categories: Detailed, historical, analytical, physiographic, and reconnaissance. The detailed and historical methods are comprehensive methods; the analytical and physiographic are intermediate; and the reconnaissance method is only approximate. Other than the reconnaissance method, each method requires determination of a T-year discharge (the peak rate of flow during a flood with long-term average recurrence interval of T years) and T-year profile and the development of a flood-boundary map. The procedure is different, however, for each method. Appraisal of the applicability of each method included consideration of its technical soundness, limitations and uncertainties, ease of use, and costs in time and money. Of the five methods, the detailed method is probably the most accurate, though most expensive. It is applicable to hydraulic and topographic conditions found in many parts of the Great Basin. The historical method is also applicable over a wide range of conditions and is less expensive than the detailed method. However, it requires more historical flood data than are usually available, and experience and judgement are needed to obtain meaningful results. The analytical method is also less expensive than the detailed method and can be used over a wide range of conditions in which the T-year discharge can be determined directly. Experience, good judgement, and thorough knowledge of hydraulic principles are required to obtain adequate results, and the method has limited application in other than rigid-channel situations. The physiographic method is applicable to rigid-boundary channels and is less accurate than the detailed method. The reconnaissance method is relatively imprecise, but it may be the most rational method to use on alluvial fans or valley floors with discontinuous channels. In general, a comprehensive method is most suitable for use with rigid-bank streams in urban areas; only an approximate method seems justified in undeveloped areas.

Water Supply Paper↗

USGS2023

Assessment of lunar resource exploration in 2022

The idea of mining the Moon, once purely science-fiction, is now on the verge of becoming reality. Taking advantage of the resources on the Moon is part of the plans of many nations and some enterprising commercial entities; demonstrating in-situ (in place) resource utilization near the lunar south pole is an explicit goal of the United States’ Artemis program. Economic extraction and sustainable management of these resources require understanding the nature, quantity, and quality of each resource. This publication aims to provide a relatively simple, but technically rigorous, assessment of the status of lunar resource exploration in 2022. Building on the experience of the U.S. Geological Survey in conducting resource assessments for Earth, we propose a general methodology for quantitative lunar resources assessments. Lunar resources can be categorized as energy, mineral, and water and classified with respect to their certainty and their recoverability. The portion of the technically recoverable resource that can be converted to a commodity within budgetary and other mission constraints can be classified as a “reserve.” For energy resources, solar energy is known to be especially abundant along some high ridges near the lunar poles and the technology to exploit it is mature. Mineral resources, largely in the form of loose rock powder that covers the surface of the Moon, are also widely accessible in large quantities. Many different technologies to convert this material into useful commodities (such as landing pads and oxygen) are currently being developed and are likely to be available for industrial-scale application within 30 years. Water ice almost certainly exists in the polar regions of the Moon but there are fundamental unanswered questions about when and how the ice formed—leaving us without knowledge of the form, quantity, quality, and distribution of lunar ice. Until rover missions bring new ground truth data, lunar ice will remain a highly speculative resource that may be both limited and non-renewable.

Circular↗

USGS2003

Alternative Sources of Energy - An Introduction to Fuel Cells

Fuel cells are important future sources of electrical power and could contribute to a reduction in the amount of petroleum imported by the United States. They are electrochemical devices similar to a battery and consist of a container, an anode, a cathode, catalysts, an intervening electrolyte, and an attached electrical circuit. In most fuel cell systems, hydrogen is supplied to the anode and oxygen to the cathode which results in the production of electricity, water, and heat. Fuel cells are comparatively efficient and reliable, have no moving parts, operate without combustion, and are modular and scale-able. Their size and shape are flexible and adaptable. In operation, they are nearly silent, are relatively safe, and generally do not pollute the environment. During recent years, scientists and engineers have developed and refined technologies relevant to a variety of fuel cells. Types of fuel cells are commonly identified by the composition of their electrolyte, which could be either phosphoric acid, an alkaline solution, a molten carbonate, a solid metal oxide, or a solid polymer membrane. The electrolyte in stationary power plants could be phosphoric acid, molten carbonates, or solid metal oxides. For vehicles and smaller devices, the electrolyte could be an alkaline solution or a solid polymer membrane. For most fuel cell systems, the fuel is hydrogen, which can be extracted by several procedures from many hydrogen-bearing substances, including alcohols, natural gas (mainly methane), gasoline, and water. There are important and perhaps unresolved technical problems associated with using fuel cells to power vehicles. The catalysts required in several systems are expensive metals of the platinum group. Moreover, fuel cells can freeze and not work in cold weather and can be damaged by impacts. Storage tanks for the fuels, particularly hydrogen, must be safe, inexpensive, of a reasonable size, and contain a supply sufficient for a trip of several hundred miles. Additional major problems will be the extensive and costly changes in the national infrastructure to obtain, store, and distribute large amounts of the fuels, and in related manufacturing

Bulletin↗

USGS1977

Verification of a model for predicting the effect of inconstant temperature on embryonic development of lake whitefish (Coregonus clupeaformis)

Eggs stripped from lake whitefish (Coregonus clupeaformis) spawning in Lake Michigan were incubated in the laboratory at temperatures similar to those on whitefish spawning grounds in Lake Michigan during December-April. Observed times from fertilization to attainment of each of 21 developmental stages were used to test a model that predicts the rate of development at daily fluctuating temperatures; the model relates rate of development for any given stage j, expressed as the reciprocal of time (Rj), to temperature (T). The generalized equation for a developmental stage is Rj = abTcT??. Observed times agreed well (5.5% mean difference for all stages) with times predicted by the model; the observed time of 135 days from fertilization to hatching (stage 21) was only 5 days (3.7%) less than the predicted time of 140 days. The model was further verified by applying it to unpublished data supplied by the Ontario Ministry of Natural Resources, for eggs from Lake Huron whitefish incubated in the laboratory in untempered Lake Huron water. The model was used to predict the effects of small temperature increases (caused by a hypothetical waste-heat discharge) on the rate of development and time of hatching of lake whitefish eggs. According to this simulation, continuous addition of waste heat sufficient to raise the temperature 1, 2, or 3 C above ambient on the spawning grounds during December-April would advance the time of hatching 8, 16, or 21 days, respectively. Possible effects of this advancement on the reproductive success of whitefish are discussed.

Technical Paper↗

USGS2004

Global climate change and wildlife in North America

It is widely accepted by the scientific community that the earth, which has always experienced climate variation, is now undergoing a period of rapid climate change that is enhanced by anthropogenic atmospheric carbon enrichment during the past 100 years. These climatic changes are accelerating and projections for the next 100 years indicate extensive warming in most (but not all) areas, changing patterns of precipitation, and a significant acceleration of sea level rise. Other likely components of ongoing climate change include changes in season lengths, decreasing range of nighttime versus daytime temperatures, declining snowpack, and increasing frequency and intensity of severe weather events. The many components of climate change, and especially the unprecedented rapid rate of change, are just as important as increasing temperatures. Wildlife species are closely adapted to their environments and readily respond to climate variation. However, as discussed in this technical review, the climate change now underway has extensive potential to affect wildlife throughout North America, either directly or indirectly through responses to changing habitat conditions. When considered in combination with other factors (e.g., pollution, ozone depletion, urbanization, etc.), the potential effect is even greater. The effects of climate change on populations and range distributions of wildlife are expected to be species specific and highly variable, with some effects considered negative and others considered positive. In North America the ranges of habitats and wildlife are predicted to generally move northward as temperatures increase. Variations in this overall pattern will be dependent upon specific local conditions, changing precipitation patterns, and the response of different species to different components of climate change. It follows that the structure of plant–animal communities will also change. Ignoring climate change is likely to increasingly result in failure to reach wildlife management objectives. Wildlife managers need to become knowledgeable about climate change, ways to cope with it, and ways to take advantage of it. Management options currently available include protecting coastal wetlands to allow for sea level rise, reducing the risks to wildlife from potential catastrophic events, adjusting yield and harvest models, accounting for known climatic variations, and taking climate change into consideration when selecting the location and other characteristics of conservation areas. Wildlife managers also need to expect the unexpected and reduce nonclimate stressors on ecosystems. Overall, wildlife managers can minimize negative impacts to wildlife and take advantage of positive aspects by planning ahead and employing adaptive management.

Technical Review↗

USGS2015

An updated conceptual model of Delta Smelt biology: Our evolving understanding of an estuarine fish

The main purpose of this report is to provide an up-to-date assessment and conceptual model of factors affecting Delta Smelt (Hypomesus transpacificus) throughout its primarily annual life cycle and to demonstrate how this conceptual model can be used for scientific and management purposes. The Delta Smelt is a small estuarine fish that only occurs in the San Francisco Estuary. Once abundant, it is now rare and has been protected under the federal and California Endangered Species Acts since 1993. The Delta Smelt listing was related to a step decline in the early 1980s; however, population abundance decreased even further with the onset of the “pelagic organism decline” (POD) around 2002. A substantial, albeit short-lived, increase in abundance of all life stages in 2011 showed that the Delta Smelt population can still rebound when conditions are favorable for spawning, growth, and survival. In this report, we update previous conceptual models for Delta Smelt to reflect new data and information since the release of the last synthesis report about the POD by the Interagency Ecological Program for the San Francisco Estuary (IEP) in 2010. Specific objectives include: 1. Provide decision makers with a practical tool for evaluating difficult trade-offs associated with management and policy decisions. 2. Provide scientists with a framework from which they can formulate and evaluate hypotheses using qualitative or quantitative models. 3. Provide the general public with a new way of learning about Delta Smelt and their habitat. Our updated conceptual model describes the habitat conditions and ecosystem drivers affecting each Delta Smelt life stage, across seasons and how the seasonal effects contribute to the annual success of the species. The conceptual model consists of two nested and linked levels of increasing specificity. The general life cycle conceptual model for four Delta Smelt life stages (adults, eggs and larvae, juveniles, and subadults) includes stationary ecosystem components and dynamic environmental drivers, habitat attributes, and Delta Smelt responses. The more detailed life stage transition conceptual models for each of the four Delta Smelt life stages describe relationships between environmental drivers, key habitat attributes, and the responses of Delta Smelt to habitat attributes as they transition from one life stage to the next. Our analyses and conceptual model show that good larval recruitment is essential for setting the stage for a strong year class; however, increased growth and survival through subsequent life stages are also needed to achieve and sustain higher population abundance. We used our conceptual model to generate 16 hypotheses about the factors that may have contributed to the 2011 increase in Delta Smelt relative abundance. We then evaluated these hypotheses by comparing habitat conditions and Delta Smelt responses in the wet year 2011 to those in the prior wet year 2006 and in the drier years 2005 and 2010. Larval recruitment was similarly high in both wet years and lower in the drier antecedent years, but juvenile and adult abundance increased only in 2011. In 2005 and 2006, the population was limited by very poor survival from the larval to the juvenile life stage. We found that in 2011, Delta Smelt may have benefitted from a combination of favorable habitat conditions throughout the year, including: 1. Adults and larvae benefitted from prolonged cool spring water temperatures, high 2011 winter and spring outflows which reduced entrainment risk and possibly improved other habitat conditions, and possibly enhanced food availability in late spring. 2. Juveniles benefitted from cool water temperatures in late spring and early summer as well as from improved food availability and low levels of harmful Microcystis. 3. Subadults also benefitted from improved food availability and from favorable habitat conditions in the large, low salinity zone (salinity 1-6) located more toward Suisun Bay,

California↗