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At least 469 records · Page 26Linked to original sources
USGS1994

'The Kesterson effect'

Hypothesized to be derived from Cretaceous marine sedimentary rocks, selenium contamination of the Kesterson National Wildlife Refuge is traced through irrigation drainage to the source bedrock of the California Coast Ranges. This biogeochemical pathway of selenium is defined here as the 'Kesterson effect.' At the refuge ponds, this effect culminated in 1983 in a 64% rate of deformity and death of embryos and hatchlings of wild aquatic birds. From the previous companion paper on irrigation drainage, the Kesterson effect has been implicated in nine of 11 reconnaissance areas studied in the western United States. Deformities have resulted in at least five of these sites. Climatic, geologic, hydrologic, and soil conditions in these reconnaissance areas are similar to those in the area surrounding Kesterson National Wildlife Refuge in the west-central San Joaquin Valley of California, in California, selenium as selenate, was ultimately found weathered with sulfur from marine sources in soluble sodium and magnesium sulfate salts, which are concentrated by evaporation on farmland soils. The Se, mobilized by irrigation drainage, is bioaccumulated to toxic levels in refuge wetland ponds that are located mainly in hydrologically closed basins and thus act as concentrating disposal points. The depositional environment of the ponds may be similar to that of the nutrient-rich continental shelf edge and slope in which Cretaceous, Eocene, and Miocene sediments found to be seleniferous in the California Coast Ranges were deposited. Bioaccumulation may be therefore a primary mechanism of selenium enrichment in ancient sediments in addition to that of the formerly suggested Cretaceous volcanic pathway.

California↗
USGS2012

Active tectonic and magmatic processes beneath Long Valley Caldera, eastern California: An overview

Geological, chronological, and structural studies of the Long Valley-Mono/Inyo Craters area document a long history of related volcanic eruptions and earthquakes controlled by regional extensional tectonics of the Basin and Range province. This activity has persisted for hundreds of thousands of years and is likely to continue. The Long Valley magma chamber had a volume approaching 3000 km 3 prior to its climatic caldera-forming eruption 0.7 m.y. ago but has been reduced to less than a third of this volume by cooling, eruption, and crystallization. Seismic evidence indicates that the main mass of the present Long Valley magma chamber is about 10 km in diameter and that its roof is 8–10 km deep with smaller cupolas as shallow as 4–5 km. Although a chamber of this size is probably capable of producing an eruption approaching 30 km 3 of lava, the record over the past 0.5 m.y. suggests that eruptions of 1 km 3 or less are far more likely. Models proposed for the current ground uplift and seismicity within the caldera require inflation of 0.1–0.2 km 3 by additional magma since mid-1979, and some models suggest that inflation was accompanied by injection of a thin dike or dikes (probably of silicic magma) into the ring fracture zone beneath the south moat. Several of the M 5.8–6.2 earthquakes that occurred in the region beginning in 1978 had non-double-couple focal mechanisms. Whether these unusual mechanisms indicate injection of mafic (low-viscosity) magma at midcrustal depths in the Sierra Nevada block south of the caldera remains debatable. Studies of calderas of various ages throughout the world indicate that episodes of unrest are relatively common and do not invariably culminate in eruptions. Although current unrest is concentrated in the south moat of Long Valley caldera, the Inyo/Mono Craters probably hold a greater potential for producing an eruption in the foreseeable future. The Inyo/Mono Craters have erupted at 500-year intervals over the past 2000–3000 years, whereas the Long Valley magma chamber has erupted at about 200,000-year intervals over the past 700,000 years. In either case, a major earthquake near the caldera could strongly influence the course of volcanic activity.

Journal of Geophysical Research Solid Earth↗
USGS2007

Scoping of Flood Hazard Mapping Needs for Hancock County, Maine

Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public awareness of the importance of the maps and responding to requests to revise them. The modernization of flood maps involves conversion of existing information to digital format and integration of improved flood hazard data as needed. To determine flood mapping modernization needs, FEMA has established specific scoping activities to be done on a county-by-county basis for identifying and prioritizing requisite flood-mapping activities for map modernization. The U.S. Geological Survey (USGS), in cooperation with FEMA and the Maine Floodplain Management Program (MFMP) State Planning Office, began scoping work in 2006 for Hancock County. Scoping activities included assembling existing data and map needs information for communities in Hancock County, documentation of data, contacts, community meetings, and prioritized mapping needs in a final scoping report (this document), and updating the Mapping Needs Update Support System (MNUSS) database with information gathered during the scoping process. The average age of the FEMA floodplain maps (all types) in Hancock County, Maine, is at least 19 years. Most of these studies were published in the late 1980s and early 1990s, and no study is more recent than 1992. Some towns have partial maps that are more recent than their study, indicating that the true average age of the data is probably more than 19 years. Since the studies were done, development has occurred in some of the watersheds and the characteristics of the watersheds have changed. Therefore, many of the older studies may not depict current conditions or accurately estimate risk in terms of flood heights or flood mapping.

Open-File Report↗
USGS1985

Preliminary report on a study to estimate flood volumes of small rural streams in Ohio: Methods, site selection, and data base

In 1981, the U.S. Geological Survey, in cooperation with the Ohio Department of Transportation and the Federal Highway Administration, began a 7-year flood-volume study of small rural basins in Ohio. This report summarizes the methods of study and describes reconnaissance and site-selection procedures, locations and characteristics of the stations, instrumentation, and methods of collecting and storing data. The first phase of this study involved an intensive field reconnaissance of about 7,000 sites, of which 32 basins were selected for detailed analysis. Drainage areas for the basins varied from 0.13 to 6.45 square miles, and main-channel slopes ranged from 7.6 to 276 feet per mile. Five years of 5-minute rainfall-runoff data will be colledted for each study site. These data will be used to calibrate and verify a rainfall-runoff model for each basin. The calibrated model will be used in conjunction with 80 years of National Weather Service 5-minute precipitation data to synthesize a representative 80-year streamflow record at each site. A Log-Pearson Type III frequency distribution will be applied to each record to define the magnitudes and frequencies of flood volumes at each site. These data will be used to develop regionalized multiple regression models for estimating flood-volume magnitudes and frequencies at small rural ungaged sites in Ohio. The report also summarizes rainfall-runoff data collected from July 1981 through September 1983, but does not interpret the data. An average of eleven event periods per site were monitored where maximum 5-minute rainfall intensities varied from 0.02 to .067 inches and maximum peak discharges varied from 1 to 1,130 cubic feet per second.

Ohio↗
USGS2006

Losses and Gains for Eight Unlined Canals Along the Purgatoire River near Trinidad, Colorado, 2000-2004

The U.S. Geological Survey conducted a field study from July 2000 through June 2004, in cooperation with the Purgatoire River Water Conservancy District, Colorado Water Conservation Board, and Bureau of Reclamation, to characterize and quantify losses and gains in Picketwire, Baca, El Moro, Chilili, Enlarged Southside, Model, John Flood, and Hoehne irrigation canals. These canals divert streamflow from the Purgatoire River between Trinidad Dam and the city of Hoehne, Colorado. Discharge measurements were made along the eight canals during steady-state conditions to identify subreaches with losses or gains. Losses and gains were computed between main-channel measurement sites along each canal by equating inflows to outflows plus flow loss or gain in the subreach. As part of this study, multiple discharge measurements also were made at Picketwire, El Moro, Chilili, Enlarged Southside, Model, John Flood, and Hoehne canal headgates to compare standard Parshall flume-rated and measured discharge at the canal headgates. Results from the discharge measurements showed that Picketwire, Chilili, and Hoehne Canals generally lose flow from the headgate to the end of the canal, although some subreaches showed gains during some measurements. Losses in Picketwire Canal ranged from about 7 percent to about 23 percent of the headgate inflow, and Chilili Canal losses ranged from about 2 percent to about 34 percent of the headgate inflow. Hoehne Canal losses ranged from only about 2 to 7 percent of the headgate inflow, which is within the uncertainty of the measurements. El Moro Canal appears to lose flow in some subreaches and gain flow in other subreaches. Despite gains in some subreaches, measurements show flow losses of about 28 percent of the headgate inflow for the entire El Moro Canal. Losses and gains in Baca, Picketwire, Chilili, and Enlarged Southside canals may be affected by the length of time that the canal has been flowing. Losses in these canals appear to decrease the longer the canal has been continuously flowing. In some cases, subreaches of some of these canals go from losing to gaining flow. Unlike some of the other canals, losses and gains in El Moro and John Flood Canal do not appear to be related to how long the canal was flowing before the measurements were made. Losses and gains in El Moro Canal are probably related to the physical attributes of the canal, such as the canal construction and proximity to other canals. Field data indicate that El Moro Canal gains flow from and loses flow to other canals. Measurements made from the Model Canal headgate to Model Reservoir show canal losses and gains ranging from 1 to 5 percent of the headgate inflow, which is less than the uncertainty of the measurements. However, measured canal losses and gains from Model Canal downstream from Model Reservoir ranged from a loss of 59 percent to a gain of 1 percent of the subreach inflow. Measured discharges at the canal headgates were usually higher than the discharges determined using the standard Parshall flume discharge tables. Of the 102 discharge measurements made at the canal headgates, 72 of the measured discharges were higher than the corresponding discharges determined using the standard Parshall flume discharge tables. This means that about 70 percent of the time, the amount of flow that was diverted into the canals was underreported. All measured discharges at the Picketwire and El Moro headgates were higher than the corresponding flume-rated discharges, and all but one measured discharge at the Chilili headgate were higher than the corresponding flume-rated discharges. Discharges measured at the remaining headgates varied from 14 percent lower to 27 percent higher than the corresponding flume-rated discharges.

Scientific Investigations Report↗
USGS1978

Report on laboratory testing of shallow sediments, Middle Atlantic Outer Continental Shelf

This report contains the results of geotechnical engineering testing on cores taken by the U.S. Geological Survey to evaluate the characteristics of the sea floor within the Baltimore Canyon Trough area. The coring took place in September, 1977 aboard the R/V ANNANDALE. During the cruise (AN-01-77), 20 vibracores were taken at 17 stations across the Continental Shelf off the coast of New Jersey (Figure 1). Table 1 shows the station locations, the water depths at each station, and the core lengths. The objective of the study was to obtain a set of representative index properties as well as strength and compressibility data on sediments from across the shelf in the Baltimore Canyon Trough area. It was anticipated that these data, although of a reconnaissance rather than a site-specific nature, would provide a useful indication of the engineering properties of these sediments. Ultimately, these data may be used for preliminary design applications and the assessment of potential hazards. In this report, the results are presented without any interpretation. An overall evaluation of all data collected during the study, including those contained in this report, presently is underway. Users of this report should be cautioned not to take these test results out of context. Two factors must be borne in mind. The first is that these tests were done on somewhat disturbed samples compared with those obtained through high-quality sampling programs onshore. Much disturbance is inevitable offshore but the significance of the disturbance on these test results has not yet been evaluated. The second factor is that these data are only part of the total set available from this project. A complete analysis of all data may lead to conclusions that are different from those based on this set of data only. The tests reported herein were performed by Geotechnical Engineers Inc., 1017 Main Street, Winchester, Massachusetts 01890, under Contract 14-08-0001-16232 of the U.S. Geological Survey. Richard Brown and Charles Osgood performed the engineering properties tests. Sally A. Wood of the U.S. Geological Survey handled the transfer of vibracores between the U.S. Geological Survey and Geotechnical Engineers Inc. and, also, assisted in the preparation of this report.

Open-File Report↗
USGS2005

Eastern rim of the Chesapeake Bay impact crater: Morphology, stratigraphy, and structure

This study reexamines seven reprocessed (increased vertical exaggeration) seismic reflection profiles that cross the eastern rim of the Chesapeake Bay impact crater. The eastern rim is expressed as an arcuate ridge that borders the crater in a fashion typical of the "raised" rim documented in many well preserved complex impact craters. The inner boundary of the eastern rim (rim wall) is formed by a series of raterfacing, steep scarps, 15-60 m high. In combination, these rim-wall scarps represent the footwalls of a system of crater-encircling normal faults, which are downthrown toward the crater. Outboard of the rim wall are several additional normal-fault blocks, whose bounding faults trend approximately parallel to the rim wall. The tops of the outboard fault blocks form two distinct, parallel, flat or gently sloping, terraces. The innermost terrace (Terrace 1) can be identified on each profile, but Terrace 2 is only sporadically present. The terraced fault blocks are composed mainly of nonmarine, poorly to moderately consolidated, siliciclastic sediments, belonging to the Lower Cretaceous Potomac Formation. Though the ridge-forming geometry of the eastern rim gives the appearance of a raised compressional feature, no compelling evidence of compressive forces is evident in the profiles studied. The structural mode, instead, is that of extension, with the clear dominance of normal faulting as the extensional mechanism.

Chesapeake Bay↗
USGS1961

Geologic map of part of the Beaver quadrangle, Utah

Tertiary volcanic and intrusive rocks underlie a large area surrounding Marysvale in southwestern Utah. Part of the Beaver quadrangle and four complete 15-minute quadrangles, Marysvale, Delano Peak, Sevier, and Monroe, have been mapped to cover the areal extent of these rocks. Mapping in the Beaver quadrangle has been restricted to the northeastern part, the area containing the western part of this volcanic province. The mapped area of the quadrangle contains the westernmost slopes of the Tushar Mountains, which slopes steeply to the eastern edge of the Great Basin. The area is thoroughly dissected and its topography is extremely rugged, having a maximum relief of more than 3,500 feet. Wildcat, Indian, and North Creeks have developed the most prominent and steeply walled canyons. The area of about 42 square miles lies about 6 miles northeast of Beaver. A main nortb-south thoroughfare, United States Highway 91, connects Beaver with Salt Lake City 208 miles to the north. Roads in the canyons of Indian Creek and North Creek allow entry into the area. The geology of the Beaver quadrangle was mapped by Callaghan, but most of the report was written by Parker from field notes, previous reports, and oral data supplied by Callaghan.

Utah↗
USGS2011

Response of lake chemistry to atmospheric deposition and climate in selected Class I wilderness areas in the western United States, 1993-2009

The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Forest Service, Air Resource Management, conducted a study to evaluate long-term trends in lake-water chemistry for 64 high-elevation lakes in selected Class I wilderness areas in Colorado, Idaho, Utah, and Wyoming during 1993 to 2009. Understanding how and why lake chemistry is changing in mountain areas is essential for effectively managing and protecting high-elevation aquatic ecosystems. Trends in emissions, atmospheric deposition, and climate variables (air temperature and precipitation amount) were evaluated over a similar period of record. A main objective of the study was to determine if changes in atmospheric deposition of contaminants in the Rocky Mountain region have resulted in measurable changes in the chemistry of high-elevation lakes. A second objective was to investigate linkages between lake chemistry and air temperature and precipitation to improve understanding of the sensitivity of mountain lakes to climate variability.

Colorado;Idaho;Utah;Wyoming↗
USGS2015

Summary of oceanographic and water-quality measurements in Rachel Carson National Wildlife Refuge, Wells, Maine, in 2013

Suspended-sediment transport is a critical element controlling the geomorphology of tidal wetland complexes. Wetlands rely on organic material and inorganic sediment deposition to maintain their elevation relative to sea level. The U.S. Geological Survey performed observational deployments to measure suspended-sediment concentration and water flow rates in the tidal channels of the wetlands in the Rachel Carson National Wildlife Refuge in Wells, Maine. The objective was to characterize the sediment-transport mechanisms that contribute to the net sediment budget of the wetland complex. We deployed a meteorological tower, optical turbidity sensors, and acoustic velocity meters at sites on Stephens Brook and the Ogunquit River between March 27 and December 9, 2013. This report presents the time-series oceanographic and atmospheric data collected during those field studies. The oceanographic parameters include water velocity, depth, turbidity, salinity, temperature, and pH. The atmospheric parameters include wind direction, speed, and gust; air temperature; air pressure; relative humidity; short wave radiation; and photosynthetically active radiation.

Maine↗
USGS2016

Low-flow frequency and flow duration of selected South Carolina streams in the Savannah and Salkehatchie River Basins through March 2014

An ongoing understanding of streamflow characteristics of the rivers and streams in South Carolina is important for the protection and preservation of the State’s water resources. Information concerning the low-flow characteristics of streams is especially important during critical flow periods, such as during the historic droughts that South Carolina has experienced in the past few decades. In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 28 selected streamgaging stations in the Savannah and Salkehatchie River Basins in South Carolina. The low-flow statistics include daily mean flow durations for the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day mean flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2014. Low-flow statistics are influenced by length of record, hydrologic regime under which the data were collected, analytical techniques used, and other factors, such as urbanization, diversions, and droughts that may have occurred in the basin. To assess changes in the low-flow statistics from the previously published values, a comparison of the low-flow statistics for the annual minimum 7-day average streamflow with a 10-year recurrence interval (7Q10) from this study was made with the most recently published values. Of the 28 streamgaging stations for which recurrence interval computations were made, 14 streamgaging stations were suitable for comparing to low-flow statistics that were previously published in U.S. Geological Survey reports. These comparisons indicated that seven of the streamgaging stations had values lower than the previous values, two streamgaging stations had values higher than the previous values, and two streamgaging stations had values that were unchanged from previous values. The remaining three stations for which previous 7Q10 values were computed, which are located on the main stem of the Savannah River, were not compared with current estimates because of differences in the way the pre-regulation and regulated flow data were analyzed.

South Carolina↗
USGS2013

Estimates of future inundation of salt marshes in response to sea-level rise in and around Acadia National Park, Maine

Salt marshes are ecosystems that provide many important ecological functions in the Gulf of Maine. The U.S. Geological Survey investigated salt marshes in and around Acadia National Park from Penobscot Bay to the Schoodic Peninsula to map the potential for landward migration of marshes using a static inundation model of a sea-level rise scenario of 60 centimeters (cm; 2 feet). The resulting inundation contours can be used by resource managers to proactively adapt to sea-level rise by identifying and targeting low-lying coastal areas adjacent to salt marshes for conservation or further investigation, and to identify risks to infrastructure in the coastal zone. For this study, the mapping of static inundation was based on digital elevation models derived from light detection and ranging (LiDAR) topographic data collected in October 2010. Land-surveyed control points were used to evaluate the accuracy of the LiDAR data in the study area, yielding a root mean square error of 11.3 cm. An independent accuracy assessment of the LiDAR data specific to salt-marsh land surfaces indicated a root mean square error of 13.3 cm and 95-percent confidence interval of ± 26.0 cm. LiDAR-derived digital elevation models and digital color aerial photography, taken during low tide conditions in 2008, with a pixel resolution of 0.5 meters, were used to identify the highest elevation of the land surface at each salt marsh in the study area. Inundation contours for 60-cm of sea-level rise were delineated above the highest marsh elevation for each marsh. Confidence interval contours (95-percent,± 26.0 cm) were delineated above and below the 60-cm inundation contours, and artificial structures, such as roads and bridges, that may present barriers to salt-marsh migration were mapped. This study delineated 114 salt marshes totaling 340 hectares (ha), ranging in size from 0.11 ha (marshes less than 0.2 ha were mapped only if they were on Acadia National Park property) to 52 ha, with a median size of 1.0 ha. Inundation contours were mapped at 110 salt marshes. Approximately 350 ha of low-lying upland areas adjacent to these marshes will be inundated with 60 cm of sea-level rise. Many of these areas are currently freshwater wetlands. There are potential barriers to marsh migration at 27 of the 114 marshes. Although only 23 percent of the salt marshes in the study are on ANP property, about half of the upland areas that will be inundated are within ANP; most of the predicted inundated uplands (approximately 170 ha) include freshwater wetlands in the Northeast Creek and Bass Harbor Marsh areas. Most of the salt marshes analyzed do not have a significant amount of upland area available for migration. Seventy-five percent of the salt marshes have 20 meters or less of adjacent upland that would be inundated along most of their edges. All inundation contours, salt marsh locations, potential barriers, and survey data are stored in geospatial files for use in a geographic information system and are a part of this report.

Maine↗
USGS2015

Regression Equations for Monthly and Annual Mean and Selected Percentile Streamflows for Ungaged Rivers in Maine

In an effort to delineate hydrologic conditions in Maine, the U.S. Geological Survey, in cooperation with the Maine Department of Transportation, used streamflow data to develop dependent variables for 130 regression equations for estimating monthly and annual mean and 1, 5, 10, 25, 50, 75, 90, 95, and 99 percentile streamflows for ungaged, unregulated rivers in Maine. Daily streamflow data from 24 rural unregulated basins with drainage areas between 14.9 and 1,419 square miles in Maine and northern New Hampshire were used in the derivation of the equations. Streamflow data collected from October 1, 1982, through September 30, 2012, were used to derive the dependent variables for this study to represent current [2015] hydrologic conditions in Maine and northern New Hampshire. Weighted least squares regression techniques were used to derive the final coefficients and measures of uncertainty for the regression equations. Eight basin characteristics serve as the explanatory variables: drainage area, distance from the coast, mean and maximum basin elevation, mean basin slope, mean basin percentage of hydrologic soil group A, fraction of sand and gravel aquifers, and percentage of open water. The largest average errors of prediction are associated with regression equations for the lowest streamflows derived for months during which the lowest streamflows of the year occur (such as the 5 and 1 monthly percentiles for August and September). The regression equations have been derived on the basis of streamflow and basin characteristics data for unregulated, rural drainage basins without substantial streamflow or drainage modifications (for example, diversions and (or) regulation by dams or reservoirs, tile drainage, irrigation, channelization, and impervious paved surfaces), therefore using the equations for regulated or urbanized basins with substantial streamflow or drainage modifications will yield results of unknown error. Input basin characteristics derived using techniques or datasets other than those documented in this report or using values outside the ranges used to develop these regression equations also will yield results of unknown error.

Maine↗
USGS1980

Helicopter airborne electromagnetic survey (using the Dighem II system) of parts of the Lake City caldera, Hinsdale County, Colorado

The data presented herein is from an airborne electromagnetic-resistivity-survey conducted by Dighem Limited of Toronto Canada for the U.S. Geological Survey. The area surveyed is located in the western San Juan Mountains near Lake City, Colorado. The general area covered is between 37°45' and 38° latitude north and 107°15' and 107°35' longitude west. The survey flying was confined to nine valleys which surround the Lake City caldera. Four blocks were surveyed from October 22 to October 27, 1979 for a total of 535 line - kilometers. The survey was flown as part of a mineral appraisal study conducted in cooperation with Bureau of Land Management (BLM). The survey was done to detect massive mineralization, mainly copper, and to locate conductive faults that may be suitable sites for uranium mineralization. To be useful, airborne electromagnetic measurements must be made within a few hundred feet of the surface. The area that was flown is so rugged that a helicopter rather than a fixed-wing aircraft was used. Fraser and Dvorak summarize the data of the survey areas as follows: in the east and south, the ground resistivities varied over a broad range—, from 20 to 1000 ohm-m. The western and northern parts of the area were characterized by resistivities mostly in the 300 to 1000 ohm-m range. Several weak to moderate EM anomalies were located that may warrant ground follow-up work.

Colorado↗
USGS2015

Southern Salish Sea Habitat Map Series: Admiralty Inlet

In 2010 the Environmental Protection Agency, Region 10 initiated the Puget Sound Scientific Studies and Technical Investigations Assistance Program, designed to support research in support of implementing the Puget Sound Action Agenda. The Action Agenda was created in response to Puget Sound having been designated as one of 28 estuaries of national significance under section 320 of the U.S. Clean Water Act, and its overall goal is to restore the Puget Sound Estuary's environment by 2020. The Southern Salish Sea Mapping Project was funded by the Assistance Program request for proposals process, which also supports a large number of coastal-zone- and ocean-management issues. The issues include the recommendations of the Marine Protected Areas Work Group to the Washington State Legislature (Van Cleve and others, 2009), which endorses a Puget Sound and coast-wide marine conservation needs assessment, gap analysis of existing Marine Protected Areas (MPA) and recommendations for action. This publication is the first of four U.S. Geological Survey Scientific Investigation Maps that make up the Southern Salish Sea Mapping Project. The remaining three map blocks to be published in the future, located south of Admiralty Inlet, are shown in figure 1. Puget Sound is a deep, fjord-type estuary covering an area of 2,330 km 2 in the Pacific Northwest region of the United States (fig. 1). It is connected to the ocean by the Strait of Juan de Fuca, a turbulent passage approximately 160 km in length and 22 km wide at its west end, expanding to over 40 km wide at its east end (Thomson, 1994). During the Pleistocene, the area was occupied several times by lobes of continental ice, resulting in a complex basin-fill of glacial and interglacial deposits that are locally as thick as 1100 m (Johnson and others, 2001). The last glaciation, called the Fraser glaciation, began after 28,800±740 14 C yr B.P. when ice started a slow expansion (Clague, 1981). At peak advance the westward Juan de Fuca lobe reached the edge of the continental shelf through the Juan de Fuca Strait shortly before 14,460±200 14 C yr B.P. (Herzer and Bornhold, 1982). The southward Puget lobe advanced to its terminal position in Puget Sound by around 14,150 14 C yr B.P. (Porter and Swanson, 1998). Ice retreated from its maximum to northern Whidbey Island by 13,650±350 14 C yr B.P. (Dethier and others, 1995). Retreating glaciers resulted in a thick sequence of ice-contact, glacial-marine sediment, and early post-glacial sediments (Linden and Schurrer, 1988). These deposits have experienced the effects of a marine transgression followed by regression, resulting in a sea-level several tens of meters lower than the present day (Linden and Schurrer, 1988). A second transgression brought sea level to about the present level by around 5,470±120 14 C yr B.P. (Clague and others, 1982) establishing the present oceanographic and geologic environment Puget Sound is separated into four interconnected basins; Whidbey, Central (Main), Hood Canal, and South (Thomson, 1994). The Whidbey, Central, and Hood Canal basins are the three main branches of the Puget Sound estuary and are separated from the Strait of Juan de Fuca by a double sill at Admiralty Inlet. The Admiralty Inlet map area includes the Inlet and a portion of the Whidbey Basin (fig. 1). The shallower South Basin is separated by a sill at Tacoma Narrows and is highly branched with numerous finger inlets. Flow within Puget Sound is dominated by tidal currents of as much as 1 m/s at Admiralty Inlet, reducing to approximately 0.5 m/s in the Central Basin (Lavelle and others, 1988). The lack of silt and clay-sized sediments in the Admiralty Inlet map area is likely a result of the strong currents (see Ground-Truth Studies for the Admiralty Inlet Map Area, sheet 3). The subtidal component of flow reaches approximately 0.1 m/s and is driven by density gradients arising from the contrast in salty ocean water at the entrance and freshwater inputs from stream flow (Lavelle and others, 1988). The total freshwater input to Puget Sound is approximately 3.4 x 10 6 m 3 /day, primarily from the Skagit River (Cannon, 1983). The subtidal circulation mostly consists of a two-layered flow in the basins with fresher water exiting at the surface and saltier water entering at depth (Ebbesmeyer and Cannon, 2001). In general, surface waters flow north and deeper waters flow south; variations arise from wind effects that can drive a surface current in the same direction as the wind, and a baroclinic response in the lower layer to about 100-m depth (Matsuura and Cannon, 1997). Oceanographic properties are influenced by temporal forcing parameters such as reduced stream flow during the 2000-01 drought that increased surface salinity and decreased differences between surface and bottom waters (Newton and others, 2003). On offshore seismic-reflection profiles, Pleistocene strata (excluding latest Pleistocene glacial and post-glacial deposits) form a distinct seismic unit, bounded below by pre-Tertiary or Tertiary basement and above by typically flat-lying latest Pleistocene to Holocene deposits that fill in erosional or depositional relief (Johnson and others, 2001). Cores from central Puget Sound have accumulation rates that range from 85 to 1200 mg/cm 2 /yr, or 0.12 to 2.4 cm/yr; the highest accumulation rates are near the southern end of central Puget Sound (Carpenter and others, 1985). Carpenter and others (1985) un-weighted arithmetic mean of accumulation rates for central Puget Sound deeper stations is 480±340 (± one standard deviation) mg/cm 2 /yr. Lavelle and others (1985) also found rates as high as 1200 mg/cm 2 /yr over the past approximately 70 years in cores in the Central Basin off of and north and south of Elliott Bay. Puget Sound basin rates are comparable to rates in midshelf silt deposits on the Washington coast north of the Columbia River (Nittrouer and others, 1979). The deep subtidal (in other words, below SCUBA depths) habitats of Puget Sound are relatively poorly known. A few subtidal surveys exist for several habitat types from the 1960s and 1970s (reviewed in Dethier, 1990), using grab and box core data. The Dethier (1990) review divides habitat up into Coast and Marine Ecological Classification Standard (CMECS) substrate, water column energy, and depth zones but does not attempt to map these habitats, rather it is an inventory of habitats found in the area and the flora and fauna associated with each habitat. The approach of the Southern Salish Sea Mapping project is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data (the undersea equivalent of satellite remote-sensing data in terrestrial mapping), acoustic backscatter, seafloor video, seafloor photography, and bottom-sediment sampling data. This approach is based in part on methods presented and data collection and product needs identified at the Washington State Seafloor Mapping Workshop (Washington State Seafloor Mapping Workshop Steering Committee, 2008), attended by coastal and marine managers and scientists. The map products display seafloor geomorphology and substrate, and identify potential marine benthic habitats. It is emphasized that the more interpretive habitat and geology maps rely on the integration of multiple, new high-resolution datasets and that mapping at small scales would not be possible without such data. Oceanographic current and wave data is not included in this analysis, however, the accompanying geographic information system (GIS) data set is designed and intended to be combined with oceanographic and biologic data sets assembled by others in the future and some of the GIS data has already been incorporated in the unpublished Nature Conservancy Benthic Habitats of Puget Sound database. This publication includes four map sheets, explanatory text, and a descriptive pamphlet. Each map sheet is published as a portable document format (PDF) file. ESRI ArcGIS compatible geotiffs (for example, bathymetry) and shapefiles (for example video observation points) will be available for download in the data catalog associated with this publication (Cochrane, 2015). An ArcGIS Project File with the symbology used to generate the map sheets is also provided. For those who do not own the full suite of ESRI GIS and mapping software, the data can be read using ESRI ArcReader, a free viewer that is available at http://www.esri.com/software/arcgis/arcreader/index.html .

Washington↗
USGS2025

Specific conductance and water type as a proxy model for salinity and total dissolved solids measurements in the Upper Colorado River Basin

Salinity levels in streams and tributaries of the Colorado River Basin have been a major concern for the United States and Mexico for over 50 years as the water is used by millions of people for domestic and industrial purposes. Recently, the United States Geological Survey expanded stream monitoring networks including the number of sites where continuous (15-min) specific conductance is measured in the Colorado River Headwaters and Gunnison River Basin located east of the Colorado-Utah state line (hereafter, UCOL). The purpose of this study is to apply a proxy method to determine salinity and total dissolved solids concentrations from specific conductance and major-ion water type that is applicable to monitoring sites in the UCOL. Within the UCOL, carbonate rich waters originate from high-elevation mountain regions in the eastern UCOL, calcium sulfate rich waters are mainly found in the western half of the UCOL including the Gunnison River Basin, and waters of variable composition are found along the lower reaches of the Colorado River and Eagle River. It was found that the chemistry of sites with variable composition changes seasonally and is impacted by both geogenic and anthropogenic processes, potentially including seasonal application of deicing road salt. The specific conductance – water type proxy can be used to reliably (±10 %) predict salinity and total dissolved solids at 66 monitoring sites in the UCOL. The method is rapid, can generate high-resolution measurements, is cost-effective, and greatly expands the utility of specific conductance measurements. Furthermore, the high-resolution estimates provide an accurate approach to determining long-term salinity loads as short-term events are accurately accounted for.

Colorado↗
USGS2019

Anderson Ranch wetlands hydrologic characterization in Taos County, New Mexico

The Anderson Ranch property (study area), located in Taos County, north-central New Mexico, was transferred from Chevron Mining, Inc. (CMI) to the Bureau of Land Management (BLM) as part of a Natural Resource Damage Assessment and Restoration (NRDAR) court-ordered settlement. The study area supports freshwater emergent wetlands and freshwater ponds. The settlement states that CMI will provide the land and a monetary settlement to support the restoration of the wetlands on the property. To best manage the study area, the BLM requires an understanding of potential effects of climate variability and groundwater withdrawals on the wetland function. This study, completed by the U.S. Geological Survey in cooperation with the BLM, provides an initial hydrologic characterization of the study area, which included literature review, collection of groundwater-level and aqueous-chemistry data, completion of a vegetation survey, and preliminary data analysis. The data compiled, collected, and analyzed as part of this study indicate that the wetlands within the study area are groundwater fed and that the water maintaining the wetlands is modern. Surface-water levels in the pond and groundwater levels in the surrounding wetland fluctuate seasonally. The hydraulic gradient in the study area is from northeast to southwest. Evapotranspiration is a main driver of water demand within the study area.

New Mexico↗
USGS2009

Late Cenozoic geology and lacustrine history of Searles Valley, Inyo and San Bernardino Counties, California

Searles Valley is an arid, closed basin lying 70 km east of the south end of the Sierra Nevada, California. It is bounded on the east and northeast by the Slate Range, on the west by the Argus Range and Spangler Hills, and on the south by the Lava Mountains; Searles (dry) Lake occupies the north-central part of the valley. During those parts of late Pliocene and Pleistocene time when precipitation and runoff from the east side of the Sierra Nevada into the Owens River were much greater than at present, a chain of as many as five large lakes was created, of which Searles Lake was third. The stratigraphic record left in Searles Valley when that lake expanded, contracted, or desiccated, is fully revealed by cores from beneath the surface of Searles (dry) Lake and partly recorded by sediments cropping out around the edge of the valley. The subsurface record is described elsewhere. This volume includes six geologic maps (scales: 1:50,000 and 1:10,000) and a text that describes the outcrop record, most of which represents sedimentation since 150 ka. Although this outcrop record is discontinuous, it provides evidence indicating the lake's water depths during each expansion, which the subsurface record does not. Maximum-depth lakes rose to the 2,280-ft (695 m) contour, the level of the spillway that led overflowing waters to Panamint Valley; that spillway is about 660 ft (200 m) above the present dry-lake surface. Several rock units of Tertiary and early Quaternary ages crop out in Searles Valley. Siltstone and sandstone of Tertiary age, mostly lacustrine in nature and locally deformed to near-vertical dips, are exposed in the southern part of the valley, as is the younger(?) upper Miocene Bedrock Spring Formation. Unnamed, mostly mafic volcanic rocks of probable Miocene or Pliocene age are exposed along the north and south edges of the basin. Slightly deformed lacustrine sandstones are mapped in the central-southwestern and southern parts of the study area. The Christmas Canyon Formation and deposits mapped as older gravel and older tufa are extensively exposed over much of the basin floor. The older gravel unit and the gravel facies of the Christmas Canyon Formation are boulder alluvial gravels; parts of these units are probably correlative. The lacustrine facies of the Christmas Canyon Formation includes the Lava Creek ash, which is dated at 0.64 Ma; the older tufa deposits may be equivalent in age to those sediments. Most of this study concerns sediments of the newly described Searles Lake Formation, whose deposition spanned the period between about 150 ka and 2 ka. Most of this formation is lacustrine in origin, but it includes interbedded alluvium. To extract as much geologic detail as possible, criteria were developed that permitted (1) intrabasin correlation of some thin outcrop units representative of only a few thousand years (or less), (2) identification of unconformities produced by subaerial erosion, (3) identification of unconformities produced by sublacustrine erosion, and (4) correlation of outcrop units with subsurface units. The Searles Lake Formation is divided into seven main units, many of which are subdivided on the five larger scale geologic maps. Units A (oldest), B, C, and D are dominantly lacustrine in origin. The Pleistocene-Holocene boundary is placed at the top of unit C. In areas that were a kilometer or more from shore at the time of deposition, deposits of units A,B, and C consist of fine, highly calcareous sand, silt, or clay; nearer to shore they consist of well-sorted coarse sand and gravel. Unit A has been locally subdivided into as many as four subunits, unit B into six subunits, and unit C into six subunits. The finer facies of units A, B, and C contain such high percentages of Caco3 that they are best described as marl. Sediments of unit C, and to a lesser extent those of unit B, are laminated with light- to white-colored layers of aragonite, calcite, or dolomite(?) that may repre

California↗