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USGS1978

Report on the beach dynamics, geology, and oil spill susceptibility of the Gulf of Alaska coastline in Glacier Bay National Monument -- Sea Otter Creek to Icy Point

Observations of the Gulf of Alaska coastline in Glacier Bay National Monument were conducted between June 1975 and July 1977 to: (1) characterize the beach environment, and (2) assess the effects of an oil spill (fig. 1). These included overflights in June 1975, June 1976, July 1976, January 1977, May 1977, and July 1977 when photographic observations were made from small fixed-wing aircraft and field observations in June 1975, July 1976, January 1977, and July 1977. Field observations consisted of measuring beach morphology, sediment distribution, and vegetation type, and characterization of beach dynamics between Fairweather Glacier and La Perouse Glacier. Ninety sediment samples were collected and analyzed for grain size in the Menlo Park USGS sediment laboratory. Beach morphology at selected sites was determined by profiling from the limit of storm deposited debris (mostly wood) to the surf zone. In 1976, 30 profiles were made, ten of which were revisited in 1977. In all 55 profiles were measured. A qualitative estimate of the effects of an oil spill for the Monument coastline between Sea Otter Creek and Icy Point as well as each of the profile stations has been made based on field observations and a susceptibility scheme by Hayes and Owens (Hayes et al., 1976; Owens, 1977).

Alaska↗

USGS1978

Reconnaissance geotechnical study of the Lucerne Granite, Maine

Physical properties, including density and strength, of the Lucerne Granite (Wing, 1958) vary because of inhomogeneities caused by fracturing and differences in texture. Two granitic facies were found: a coarse-grained variety in the southern part of the body and near the edges of the pluton and a medium-grained porphyritic variety in the central and northern sections. Point-load strength tests indicate that the medium-grained porphyritic granite is stronger than the coarse-grained porphyritic or non-porphyritic granite. Results of bulk and grain density tests suggest that rock strength in the weaker granite samples is controlled by microfractures. In the pluton, joint trends changed from a scattered pattern in the north to a preferred orientation in the south. Because it has a simple joint pattern and is homogeneous in texture, the southern part of the Lucerne Granite is a more suitable area for excavation and fluid storage than the northern section.

Maine↗

USGS1978

Regional and local networks of horizontal control, Cerro Prieto geothermal area, Mexico

The Cerro Prieto geothermal area in the Mexicali Valley 30 km southeast of Mexicali, Baja California, is probably deforming due to (1) the extraction of large volumes of steam and hot water, and (2) active tectonism. Two networks of precise horizontal control were established in Mexicali Valley by the U.S. Geological Survey in 1977-78 to measure both types of movement as they occur. These networks consisted of (1) a regional trilateration net brought into the mountain ranges west of the geothermal area from survey stations on an existing U.S. Geological Survey crustal-strain network north of the international border, and (2) a local net tied to stations in the regional net and encompassing the area of present and planned geothermal production. Survey lines in this net were selected to span areas of probable ground-surface movements in and around the geothermal area. Electronic distance measuring (EDM) instruments, operating with a modulated laser beam, were used to measure the distances between stations in both networks. The regional net was run using a highly precise long-range EDM instrument, helicopters for transportation of men and equipment to inaccessible stations on mountain peaks, and a fixed wing airplane flying along the line of sight. Precision of measurements with this complex long-range system approached 0.2 parts per million of line length. The local net was measured with medium range EDM instrument requiring minimal ancillary equipment. Precision of measurements with this less complex system approached 3 parts per million for the shorter line lengths. The detection and analysis of ground-surface movements resulting from tectonic strains or induced by geothermal fluid withdrawal is dependent on subsequent resurveys of these networks.

Baja California↗

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↗

USGS1985

Inertial instrument system for aerial surveying

An inertial guidance system for aerial surveying has been developed under contract to the U.S. Geological Survey. This prototype system, known as the aerial profiling of terrain (APT) system, is designed to determine continuously the positions of points along an aircraft flight path, or the underlying terrain profile, to an accuracy of + or - 0.5 ft (15 cm) vertically and + or - 2 ft (61 cm) horizontally. The system 's objective thus is to accomplish, from a fixed-wing aircraft, what would traditionally be accomplished from ground-based topographic surveys combined with aerial photography and photogrammetry. The two-part strategy for measuring the terrain profile entails: (1) use of an inertial navigator for continuous determination of the three-coordinate position of the aircraft, and (2) use of an eye-safe pulsed laser profiler for continuous measurement of the vertical distance from aircraft to land surface, so that the desired terrain profile can then be directly computed. The APT system, installed in a DeHavilland Twin Otter aircraft, is typically flown at a speed of 115 mph (105 knots) at an altitude of 2,000 ft (610 m) above the terrain. Performance-evaluation flights have shown that the vertical and horizontal accuracy specifications are met. (USGS)

Open-File Report↗

USGS1994

A compilation of sulfur dioxide and carbon dioxide emission-rate data from Mount St. Helens during 1980-88

Airborne monitoring of Mount St. Helens by the USGS began inMay 1980 for sulfur dioxide emissions and in July 1980 forcarbon dioxide emissions. A correlation spectrometer, orCOSPEC, was used to measure sulfur dioxide in Mount St.Helens' plume. The upward-looking COSPEC was mounted in afixed-wing aircraft and flown below and at right angles to theplume. Typically, three to six traverses were made underneaththe plume to determine the SO2 burden (concentration xpathlength) within a cross-section of the plume. Knowing theburden along with the plume width and plume velocity (assumedto be the same as ambient wind speed), we could then calculatethe emission rate of SO2. The use of correlation spectroscopyfor determining the sulfur dioxide output of volcanoes is wellestablished and the technique has been discussed in detail bya number of investigators (Malinconico, 1979; Casadevall andothers, 1981; Stoiber and others, 1983).Carbon dioxide in the Mount St. Helens plume was measured byan infrared spectrometer tuned to the 4.26 um CO2 absorptionband. An external sample tube was attached to the fuselage ofa twin-engine aircraft to deliver outside air to the gas cellof the spectrometer. The aircraft was then flown at severaldifferent elevations through the plume at right angles toplume trajectory to define plume area and carbon dioxideconcentration in a vertical cross-section of the plume. Thesetwo parameters along with the density of CO2 for the altitudeof the plume and the plume velocity (assumed as above to beequal to ambient wind speed) were then used to calculate theCO2 emission rate.

Open-File Report↗

USGS1996

Level II scour analysis for Bridge 42 (BETHTH00860042) on Town Highway 86, crossing Gilead Brook, Bethel, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure BETHTH00860042 on town highway 86 crossing Gilead Brook, Bethel, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge available from VTAOT files were compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the Green Mountain physiographic province of central Vermont in the town of Bethel. The 11.4-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the upstream banks are tree covered and the downstream banks are covered with shrubs and brush. In the study area, Gilead Brook is probably incised, has a sinuous channel with a slope of approximately 0.012 ft/ft, an average channel top width of 53 ft, and an average channel depth of 5 ft. The predominant channel bed material is gravel to cobbles (D 50 is 85.6 mm or 0.281 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 30, 1994, indicated that the reach was stable. The town highway 86 crossing of Gilead Brook is a 28-ft-long, one-lane bridge consisting of one 25-foot clear-span structure with a concrete deck (Vermont Agency of Transportation, written commun., August 24, 1994). The bridge is supported by concrete abutments with wingwalls. The bridge skew is approximately 5 degrees and there is no opening-skew-to-roadway. A scour hole approximately 1 ft deeper than the mean thalweg depth was observed along the left bank, near the upstream bridge face during the Level I assessment. There is also approximately 1 ft of scour along the left abutment of the bridge, near the upstream wing wall, exposing the footing. There is type-one (less than 12 in diameter) protection on the US left wingwall and type-two (less than 36 in diameter) along the US and DS right wingwalls. There is no protection along the abutments. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0 to 1.9 ft. The worst-case contraction scour occurred at the incipient-overtopping discharge and the 100-year discharge. Abutment scour ranged from 8.6 to 15.7 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Many factors, including historical performance during flood events, the geomorphic assessment, scour protection, and the results of the hydraulic analyses, must be considered to properly assess the validity of abutment scour results. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein, based on the consideration of additional contributing factors and engineering judgement.

Vermont↗

USGS1997

Level II scour analysis for Bridge 12 (SUNDFLR0030012) on Forest Land Road 3, crossing Roaring Branch Brook, Sunderland, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure SUNDFLR0030012 on Forest Land Road (FLR) 3 (FAS 114) crossing Roaring Branch Brook, Sunderland, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in southwestern Vermont. The 4.93-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is dense forest along the left bank and primarily shrubs and trees along the right bank, both upstream and downstream of the bridge. In the study area, Roaring Branch Brook has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 33 ft and an average bank height of 4 ft. The channel bed material ranges from cobble to bedrock with a median grain size (D 50 ) of 139 mm (0.457 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 30, 1996, indicated that the reach was stable. Forest Land Road 3 (FAS 114) crossing of Roaring Branch Brook is a 37-ft-long, two-lane bridge consisting of one 35-foot steel-beam span (Vermont Agency of Transportation, written communication, December 14, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 30 degrees to the opening while the opening-skew-to-roadway is 15 degrees. The scour protection measures at the site included type-3 stone fill (less than 48 inches diameter) along the left and right abutments, along the upstream left and downstream right wing walls and along the downstream right bank. Type-4 (less than 60 inches diameter) stone fill was found along the upstream right and downstream left wingwalls and along the downstream left bank. Type-2 (less than 36 inches diameter) stone fill scour protection was found along the upstream left and right banks. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows was calculated to be 0.0 ft. Abutment scour ranged from 4.3 to 10.4 ft. The worst-case abutment scour occurred at the 500-year discharge along the right abutment. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗

USGS1997

Level II scour analysis for Bridge 43 (CHESVT00110043) on State Highway 11, crossing the Middle Branch Williams River, Chester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CHESVT00110043 on State Route 11 crossing the Middle Branch of the Williams River, Chester, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is principally in the Green Mountain section of the New England physiographic province in southeastern Vermont. The 13.7-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is predominantly forest except for the area downstream and right of the bridge which is pasture. In the study area, the Middle Branch of the Williams River has a sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 77 ft and an average bank height of 8 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 76.6 mm (0.251 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 11, 1996, indicated that the reach was laterally unstable. Lateral instability was evident from the several point bars and cut banks located through the study reach. The State Route 11 crossing of the Middle Branch of the Williams River is a 76-ft-long, two-lane bridge consisting of two 37-foot concrete Tee-beam spans (Vermont Agency of Transportation, written communication, March 29, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 35 degrees to the opening. The computed opening-skew-to-roadway was 30 degrees but the historical records indicate this angle is 25 degrees. Scour protection measures at the site consist of type-1 stone fill (less than 12 inches diameter) along the downstream banks and the upstream right wing wall. Type-2 (less than 36 inches diameter) stone fill protection is noted on the upstream and downstream left wingwalls and upstream along the left bank. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0.0 to 1.5 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.2 to 10.7 ft. The worst-case abutment scour occurred at the 500-year discharge for the right abutment. Pier scour ranged from 7.3 to 8.6 ft. The worst-case pier scour occurred at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗

USGS1997

Level II scour analysis for Bridge 38 (ANDOVT00110038) on State Route 11, crossing the Middle Branch Williams River, Andover, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure ANDOVT00110038 on State Route 11 crossing the Middle Branch Williams River, Andover, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in south central Vermont. The 5.65-mi 2 drainage area is in a predominantly rural and forested basin. Upstream and downstream of the study site banks and overbanks are forested. In the study area, the Middle Branch Williams River has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 44 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to boulders with a median grain size (D 50 ) of 54.0 mm (0.177 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 5, 1996, indicated that the reach was stable. The State Route 11 crossing of the Middle Branch Williams River is a 33-ft-long, two-lane bridge consisting of one 31-foot concrete T-beam span (Vermont Agency of Transportation, written communication, March 29, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 55 degrees to the opening while the measured opening-skew-to-roadway is 45 degrees. There were no scour problems observed during the Level I assessment. Type-4 stone fill (less than 60 inches diameter) and type-3 stone fill (less than 48 inches diameter) was present on the left bank upstream and right bank upstream respectively. Type-2 stone fill (less than 36 inches diameter) was present in the upstream left wing wall area. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 1.8 to 3.4 ft. The worst-case contraction scour occurred at the 500-year flow. Abutment scour ranged from 12.0 to 14.0 ft. The worst-case abutment scour occurred at the 500-year flow at the right abutment. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗

USGS1997

Level II scour analysis for Bridge 22 (WALDTH00180022) on Town Highway 18, crossing Coles Brook, Walden, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure WALDTH00180022 on Town Highway 18 crossing Coles Brook also known as Joes Brook, Walden, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in northeastern Vermont. The 12.5-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is predominantly forested while the downstream left bank is shrub and brushland. In the study area, the Coles Brook has an incised, sinuous channel with a slope of approximately 0.004 ft/ft, an average channel top width of 54 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to bedrock with a median grain size (D50) of 124.1 mm (0.407 ft). The D 50 was taken from a pebble count in the downstream channel, because the upstream channel is primarily bedrock. The geomorphic assessment at the time of the Level I and Level II site visit on August 8, 1995, indicated that the reach was stable. The Town Highway 18 crossing of the Coles Brook is a 46-ft-long, one-lane bridge consisting of one 44-foot steel-beam span with a wooden deck (Vermont Agency of Transportation, written communication, April 5, 1995). The opening length of the structure parallel to the bridge face is 41.4 ft. The bridge is supported by a vertical, concrete abutment with wingwalls on the left and by a vertical, stone abutment with stone wingwalls with a concrete cap on the right. The channel is skewed approximately 5 degrees to the opening while the computed opening-skew-to-roadway is 10 degrees. The only scour protection measure at the site was a stone wall along the upstream left bank and type-2 stone fill (less than 36 inches diameter) along the entire base length of the upstream left wingwall, left abutment, and downstream left wing wall. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100-year and 500-year discharges. Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows was 0.0 ft. Abutment scour ranged from 6.4 to 7.9 ft at the left abutment and from 11.8 to 14.9 ft at the right abutment. The worst-case abutment scour occurred at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗

USGS2004

Riverbed elevations and water quality of the Missouri River at Sioux City, Iowa, 2002-03

The U.S. Geological Survey, in cooperation with the City of Sioux City, Iowa, conducted an investigation of the Missouri River, during 2002-2003, to assess changes in riverbed elevations from its confluence with the Big Sioux River, downstream to the area of the Sioux City municipal well field. Water-quality samples also were collected across the Missouri River to provide additional information on the differences between the water quality of the Missouri River and Big Sioux River in the well field area. The water supply at Sioux City, Iowa, is withdrawn from fourteen vertical wells and one horizontal collector well. Twelve vertical wells and the collector well are completed in the alluvial sand and gravel aquifer adjacent to the Missouri River at Sioux City. The well field is located on the left bank (looking downstream) of the Missouri River about 0.5 mile upstream from USGS streamflow gage 06486000, and approximately 5,000 feet downstream from the confluence with the Big Sioux River. The Missouri River, adjacent to the Sioux City alluvial well field, consists of the combined streamflows from the Missouri and the Big Sioux Rivers. The streamflows do not appear to be well mixed downstream from the confluence, and the streamflow directly adjacent to the well field could be predominately from the Big Sioux River. The U.S. Geological Survey measures streamflow on the Missouri River at Sioux City, Iowa (USGS streamflow gage 06486000). The riverbed of the Missouri River at Sioux City consists of a sequence of sands and gravels. The surface of the riverbed is undulatory, with continuously migrating riverbed forms, 5 to 8 feet in relief, of sand and gravel. Measurements of riverbed elevations from October 1, 2002, to September 30, 2003, showed an annual change of as much as 8 feet with the majority of the riverbed change closer to 5 feet. The largest change occurred near a wing dike on the Nebraska side of the Missouri River. On the Iowa side, the annual change was close to 5 feet. The results showed that channel fill occurred in the winter months and scour occurred during the summer months. Results of analyses of water samples collected at five locations across the Missouri River, near the municipal well field, were similar for most samples. Higher values of specific conductance and turbidity were recorded on the Iowa side of the Missouri River, the side from which the Big Sioux River enters upstream. Higher concentrations of chloride, ammonia nitrogen, nitrate nitrogen, and atrazine also were detected on the Iowa side of the Missouri River. Based on these results, there does not appear to be complete mixing of water from the Missouri and Big Sioux Rivers near the municipal well field.

Iowa↗

USGS2020

Breeding birds of the upper Mississippi River floodplain forest: One community in a changing forest, 1994 to 1997

Floodplain forest on the upper Mississippi River (UMR), a unique habitat in the Midwest that is important for many bird species, has been reduced and is undergoing continued reduction and changes in structure and species diversity because of river engineering and invasive species. Hydrological changes are causing tree diversity to decline favoring Acer saccharinum (silver maple) and Fraxinus pennsylvanica (green ash). Invasive Phalaris arundinacea (reed canary grass, Phalaris ) threatens tree regeneration, and recent Agrilus planipennis (emerald ash borer) arrival threatens to decimate the important ash component of the forest canopy. During the 1990s, virtually no information was available about breeding songbird species and abundances on the UMR floodplain forest from along many river miles and a broad range of forest situations (for example, mainland, island, edge, interior). From 1994 to 1997, we surveyed breeding birds and sampled vegetation at 391 random points on UMR floodplain forest along a latitudinal gradient from Red Wing, Minnesota, to Clinton, Iowa, to characterize bird assemblages and associations with gradients in forest structure at survey points (local scale) and land cover composition within a 200-meter radius of survey points (landscape scale). Eighty-six bird species were detected during the study, but 28 species comprised 90 percent of all detections. Species that are typically associated with woodland edge or are tolerant of fragmentation were the most common: Setophaga ruticilla (American Redstart), Troglodytes aedon (House Wren), Turdus migratorius (American Robin), Quiscalus quiscula (Common Grackle), and Vireo gilvus (Warbling Vireo). Species typically associated with large forest patches— Setophaga cerulea (Cerulean Warbler), Hylocichla mustelina (Wood Thrush), and Dryocopus pileatus (Pileated Woodpecker)—were rare. Principal components analyses consistently described local habitat gradients related to canopy cover and Phalaris presence and described landscape gradients related to forest area and areas of open land cover types. However, nonmetric multidimensional scaling revealed no pattern in bird assemblages. Canonical correspondence analyses with local habitat variables for each year revealed that bird assemblages were affected by canopy cover, the presence of Phalaris , and the number of tree species. Four bird species were consistently associated with Phalaris presence or negatively with canopy cover, and no species were associated with the number of tree species variable. Although landscape variables were significantly related to the bird assemblage in canonical correspondence analyses, no bird species were consistently related to any landscape variable. These results indicate that there is one assemblage of forest birds on the UMR composed mainly of edge-tolerant species. Species associated with lower canopy cover and Phalaris presence may be favored to increase in abundance as canopy cover opens as trees die and Phalaris becomes more prevalent.

Illinois, Iowa, Minnesota, Wisconsin↗

USGS2002

Ground-water resources of the uppermost confined aquifers, southern Wadena County and parts of Ottertail, Todd, and Cass Counties, central Minnesota, 1997–2000

Water managers are concerned about the increase of ground-water withdrawals from high-capacity wells completed in the uppermost confined aquifers in southern Wadena County. The hydrogeologic units of primary interest in the study area are the surficial aquifer, the uppermost confining units, and the uppermost confined aquifers. The surficial aquifer underlies all but portions of the eastern, western, and south-central parts of the study area, and is as much as 70 ft thick. The thickness of the uppermost confined aquifers ranges from 0 to 72 ft. The thickness of the aquifers is greatest in the south-central and west-central parts of the study area, where thicknesses exceed 50 ft. Depth to the top of the uppermost confined aquifers ranges from 23 to 132 ft. The thickness of the uppermost confining units ranges from 4 to 132 ft. The regional direction of flow in the uppermost confined aquifers is to the east, southeast, and southwest toward the Crow Wing River in the eastern part of the study area and toward the Leaf River in the western part. Sources of water to the uppermost confined aquifers are leakage of water through overlying till and clay and ground-water flow from adjoining aquifers outside the study area. Discharge from the uppermost confined aquifers is by withdrawal from wells and to the surficial aquifer in river valleys. The theoretical maximum well yields for the uppermost confined aquifers range from less that 175 gal/min to greater than 2,000 gal/min and are greatest in areas of greatest aquifer thickness and transmissivity. The water budget for the calibrated steady-state simulation indicated that areal recharge to the surficial aquifer is 86.9 percent of the water to the aquifers, with leakage to the uppermost confined aquifers contributing 6.9 percent. The largest discharges from the aquifers are leakage to streams (54.5 percent) and ground-water evapotranspiration (41.4 percent). The simulated transient water budget for 1999 indicated that the principal sources of water to the aquifers were areal recharge to the surficial aquifer and release from storage. The principal discharges were stream-aquifer leakage, addition to storage, and ground-water evapotranspiration. Results of the steady-state simulation with anticipated increases in ground-water withdrawals indicated maximum drawdowns of 0.3 ft in the surficial aquifer and 0.9 ft in the uppermost confined aquifers due to the anticipated increases in ground-water withdrawals. Model results indicate that the anticipated increases in withdrawals during a drought may lower water levels 2 to 4 ft regionally in much of both the surficial and uppermost confined aquifers. Water-level declines in the surficial aquifer of about 6 ft may occur in Wadena and in the central part of the aquifer south of the Leaf River. Results of the transient simulation indicate that the anticipated increases in withdrawals during a drought would increase seasonal declines in the surficial and uppermost confined aquifers less than 1 and 2 ft, respectively. Model results indicate that greater than anticipated increases in withdrawals during periods of normal precipitation will have minimal effects on ground-water levels and streamflow in the area. In the uppermost confined aquifers, for example, water levels may decline an average of 0.13 ft regionally, with maximum declines of 0.8 to 2.1 ft near Wadena and Verndale. Greater than anticipated increases in withdrawals would cause decreases in ground-water discharge to streams of about 1.4 percent (2.5 ft 3 /s) of 1998-99 steady-state conditions.

Minnesota↗

USGS1997

Water-quality assessment of part of the upper Mississippi River Basin, Minnesota and Wisconsin — Nitrogen and phosphorus in streams, streambed sediment, and ground water, 1971-94

Nitrogen and phosphorus in streams, streambed sediment, and ground water were summarized using data from Federal, state, and local agencies as part of an analysis of historical water-quality data for the Upper Mississippi River Basin study unit of the U.S. Geological Survey's National Water-Quality Assessment Program. The Upper Mississippi River Basin study unit encompasses the drainage of the Mississippi River from the source to the outlet of Lake Pepin. This report focuses on a 19,500-square-mile study area in the eastern part of the study unit. The study area included the part of the Upper Mississippi River Basin from Royalton, Minnesota, to the outlet of Lake Pepin, located near Red Wing, Minnesota; the Minnesota River Basin from Jordan, Minnesota, to the confluence with the Mississippi River; and the entire drainage basins of the St. Croix, Cannon, and Vermillion Rivers. The Twin Cities metropolitan area, with a population of approximately 2.3 million people, is located in the south-central part of the study area. Fertilizers and livestock manure were the greatest sources of nitrogen and phosphorus applied to the land surface of the study unit. Approximately 60 percent of the fertilizer was applied to the Minnesota River Basin, which drains agricultural areas in the southern and western parts of the study unit. Concentrations of total nitrite plus nitrate nitrogen, total nitrogen, and total phosphorus in streams, generally were greatest in the tributaries to the Mississippi River draining agricultural areas in the western and southern part of the study area. Concentrations of these constituents generally were least in tributaries draining forested land. The greatest total nitrite plus nitrate nitrogen concentrations generally occurred during the spring and summer in streams draining agricultural areas and in the winter in streams draining forested areas. Total phosphorus concentrations generally were greatest in the spring and summer for all streams. Total nitrite plus nitrate nitrogen, total nitrogen, and total phosphorus concentrations in the Mississippi River increased substantially downstream from the Minnesota River and downstream from wastewater discharges in the Twin Cities metropolitan area. Total ammonia and dissolved orthophosphate concentrations generally were greatest at sites on the Mississippi and Minnesota Rivers downstream from wastewater discharges from the Twin Cities metropolitan area. Total nitrite plus nitrate nitrogen concentrations in streams generally were less than the Maximum Contaminant Level of 10 mg/L (as nitrogen) established by the U.S. Environmental Protection Agency. Total phosphorus concentrations in streams generally were greater than the 0.1 mg/L concentration recommended by the U.S. Environmental Protection Agency at sites located in agricultural areas and on the Mississippi River downstream from its confluence with the Minnesota River. Phosphorus and nitrogen yields were greatest in watersheds primarily draining agricultural land. The majority of the nitrogen and phosphorus loading to the Mississippi River was from the Minnesota River. In the Minnesota River, the nitrogen load primarily was total nitrite plus nitrate nitrogen. Despite increases in fertilizer usage during 1982-91, most stream sites outside of the Twin Cities metropolitan area had no temporal trends in total nitrite plus nitrate nitrogen, total phosphorus, or dissolved orthophosphate concentrations for water years 1984-93. Most sites had a decrease in total ammonia nitrogen concentrations, possibly a result of improvements in wastewater treatment. In the Twin Cities metropolitan area, decreases in total ammonia concentrations in the Mississippi and Minnesota Rivers coincided with increases in total nitrite plus nitrate nitrogen concentrations, probably a result of wastewater treatment plants initiating nitrification processes. Nitrite plus nitrate nitrogen concentrations in ground water reflect land uses and hydrogeologic settings of major aquifers in the study area. Unconfined sand and gravel, buried sand and gravel, and the Prairie du Chien-Jordan were the aquifers most frequently sampled for nitrite plus nitrate nitrogen because they are the principal sources of ground water in the study area. The greatest nitrite plus nitrate nitrogen concentrations reported by Federal and state agencies, some exceeding the U.S. Environmental Protection Agency's Maximum Contaminant level of 10 mg/L by a factor of four, were in water from shallow wells in agricultural and mixed forested and agricultural areas. Water sampled from buried sand and gravel aquifers, which are more shielded from substances leaching from the land surface by layers of clay or till, generally had lower nitrite plus nitrate nitrogen concentrations than water from unconfined sand and gravel aquifers. Nitrite plus nitrate nitrogen concentrations in water samples from the Prairie du Chien-Jordan aquifer were greatest in the Wisconsin part of the study area and in the vicinity of the Cannon River, where the aquifer is commonly unconfined, exposed at land surface, and overlain by agricultural or by mixed forested and agricultural land covers. Dissolved phosphorus concentrations in ground water in the study area generally were near detection limits of 0.01 mg/L or lower, indicating that surface-water eutrophication from phosphorus may be more likely to occur from overland runoff of phosphorus compounds and from direct discharges of treated wastewater than from ground-water base flow. The greatest concentrations of dissolved phosphorus in ground water generally were detected in water samples from wells in urban portions of the study area.

Minnesota, Wisconsin↗

USGS1997

Field screening of water quality, bottom sediment, and biota associated with irrigation drainage in the Yuma Valley, Arizona, 1995

Because of concerns expressed by the U.S. Congress and the environmental community, the Department of the Interior began a program in late 1985 to identify the nature and extent of water-quality problems induced by irrigation that might exist in the western States. Surface water, bottom sediment, and biota were collected from March through September 1995 along the lower Colorado River and in agricultural drains at nine sites in the Yuma Valley, Arizona, and analyzed for selected inorganic and organic constituents. Analyses of water, bottom sediment, and biota were completed to determine if irrigation return flow has caused, or has the potential to cause, harmful effects on human health, fish, and wildlife in the study area. Concentrations of dissolved solids in surface-water samples collected in March generally did not vary substantially from surface-water samples collected in June. Concentrations of dissolved solids ranged from 712 to 3,000 milligrams per liter and exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 500 milligrams per liter for drinking water. Concentrations of chloride in 9 of 18 water samples and concentrations of sulfate in 16 of 18 water samples exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 250 milligrams per liter for drinking water. Calcium and sodium were the dominant cations, and chloride and sulfate were the dominant anions. The maximum selenium concentration of 8 micrograms per liter exceeded the U.S. Environmental Protection Agency aquatic-life chronic criterion of 5 micrograms per liter. Concentrations of lead in 7 of 18 water samples and concentrations of mercury in 4 of 18 water samples exceeded the aquatic-life cronic criteria of 3.2 and 0.012 micrograms per liter, respectively. Concentrations of antimony, beryllium, cadmium, and silver in the water samples were below analytical reporting limits. Arsenic was detected in 3 of 9 bottom-sediment samples, and concentrations ranged from 11 to 16 micrograms per gram. Concentrations ofaluminum, beryllium, boron, copper, lead, and zinc were highest in samples from Main Drain at southerly international boundary near San Luis, Arizona. Selenium was detected in all bottom-sediment samples, and concentrations ranged from 0.1 to 0.7 micrograms per gram. Concentrations of cadmium, europium, homium, mercury, molybdenum, silver, tantalum, tin, and uranium were below analytical reporting limits in the bottom-sediment samples. Concentrations of trace elements in bottom-sediment samples were within the ranges found in a study of soils of the western United States and did not indicate a significant accumulation of these constituents. p,p'Dichlorodiphenyldichloroethylene (commonly referred to as p,-p'-DDE) was detected in one bottom-sediment sample at a concentration of 1.4 micrograms per gram. No other organochlorine compounds were detected in the bottom-sediment samples. DDE was present in all fish and bird samples. Almost one-half of the fish samples contained DDE residues that were two times higher than the mean calculated for a national study in 1984-85. Twenty-tree percent of the fish contained more than three times the national mean. Fish from downstream parts of the Main Drain had the highest concentrations of DDE. Although concentrations of DDE in fish and in bird carcasses and eggs were above background levels, residues generally were below thresholds associated with chronic poisoning and reproductive problems in figh and wildlife. Concentrations of 18 trace elements were detected in cattail (Typha sp.) roots, freshwater clam (Corbicula fluminea), fish, and bird samples. Selenium in most fish and in livers of red-winged (Agelaius phoeniceus) and yellow-headed (Xanthocephalus xanthocephalus) blackbirds was above background concentrations but below toxic concentrations. In contrast, selenium was present in a killdeer (Charadrium vociferus) liver sample at potentially toxic con

Water-Resources Investigations Report↗

USGS2015

Serologic evidence of influenza A (H14) virus introduction into North America

Although a diverse population of influenza A viruses (IAVs) is maintained among ducks, geese, shorebirds, and gulls, not all of the 16 avian hemagglutinin (HA) subtypes are equally represented (1). The 14th HA subtype, commonly known as the H14 subtype, was historically limited to isolates from the former Soviet Union in the 1980s (2) and was not subsequently detected until 2010, when isolated in Wisconsin, USA from long-tailed ducks and a white-winged scoter (3–5). In the United States, the H14 subtype has since been isolated in California (6), Mississippi, and Texas (7); and has been reported in waterfowl in Guatemala (7). In this study, we examined whether there was serologic evidence of H14 spread among ducks in North America before (2006–2010) and after (2011–2014) the initial detection of the H14 subtype virus on this continent.

Emerging Infectious Diseases↗

USGS2007

Effects of predation by sea ducks on clam abundance in soft-bottom intertidal habitats

Recent studies have documented strong, top-down predation effects of sea ducks on mussel populations in rocky intertidal communities. However, the impact of these gregarious predators in soft-bottom communities has been largely unexplored. We evaluated effects of predation by wintering surf scoters Melanitta perspicillata and white-winged scoters M. fusca on clam populations in soft-bottom intertidal habitats of the Strait of Georgia, British Columbia. Specifically, we documented spatial and temporal variation in clam density (clams m –2 ), scoter diet composition, and the consequences of scoter predation on clam abundance. Of the 3 most numerous clams, Manila clams Venerupis philippinarum and varnish clams Nuttallia obscurata were the primary prey items of both scoter species, while clams of the genus Macoma were rarely consumed by scoters. Between scoter arrival in the fall and departure in the spring, Manila clams decreased in density at most sample sites, while varnish clam densities did not change or declined slightly. Our estimates of numbers of clams consumed by scoters accounted for most of the observed declines in combined abundance of Manila and varnish clams, despite the presence of numerous other vertebrate and invertebrate species known to consume clams. For Macoma spp., we detected an over-winter increase in density, presumably due to growth of clams too small to be retained by our sieve (<5 mm) during fall sampling, in addition to the lack of predation pressure by scoters. These results illustrate the strong predation potential of scoters in soft-bottom intertidal habitats, as well as their potentially important role in shaping community structure.

British Columbia↗