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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 325 records · Page 18Linked to original sources
USGS1996

Galileo's first images of Jupiter and the Galilean satellites

The first images of Jupiter, Io, Europa, and Ganymede from the Galileo spacecraft reveal new information about Jupiter's Great Red Spot (GRS) and the surfaces of the Galilean satellites. Features similar to clusters of thunderstorms were found in the GRS. Nearby wave structures suggest that the GRS may be a shallow atmospheric feature. Changes in surface color and plume distribution indicate differences in resurfacing processes near hot spots on lo. Patchy emissions were seen while Io was in eclipse by Jupiter. The outer margins of prominent linear markings (triple bands) on Europa are diffuse, suggesting that material has been vented from fractures. Numerous small circular craters indicate localized areas of relatively old surface. Pervasive brittle deformation of an ice layer appears to have formed grooves on Ganymede. Dark terrain unexpectedly shows distinctive albedo variations to the limit of resolution.

Science↗
USGS1993

Nonfuel mineral resources in the United States-Mexico border region: A progress report on information available from the Center for Inter-American Mineral Resource Investigations (CIMRI)

The exploitation of minerals has played a significant role in population growth and development of the U.S.Mexico border region. Recent proposed changes in regulations related to mining in the United States and changes in mining and investment regulations in Mexico have led to increased mineral exploration and development in Mexico, especially in the border region. As a preliminary step in the study of the mineral industry of this area, the Center for Inter-American Mineral Resource Investigations (CIMRI) of the U.S. Geological Survey has compiled mine and occurrence data for nonfuel minerals in the border region. Analysis of this information indicates that a wide variety of metallic and industrial mineral commodities are present which can be used in agriculture, infrastructure, environmental improvement, and other industries. Therefore, mining will continue to play a significant role in the economy of this region.

Circular↗
USGS2004

Water quality in the Great and Little Miami River Basins, Ohio and Indiana, 1999-2001

This report contains the major findings of a 1999?2001 assessment of water quality in the Great and Little Miami River Basins. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. This report is intended for individuals working with water-resource issues in Federal, State, or local agencies, universities, public interest groups, or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams and ground water in areas near where they live and how that water quality compares to the quality of water in other areas across the Nation. The water-quality conditions in the Great and Little Miami River Basins summarized in this report are discussed in detail in other reports that can be accessed from (http://oh.water.usgs.gov/miam/intro.html). Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented in this report, in addition to reports in this series from other basins, can be accessed from the national NAWQA Web site (http://water.usgs.gov/nawqa).

Circular↗
USGS2004

Water quality in the Yellowstone River Basin, Wyoming, Montana, and North Dakota, 1999-2001

This report contains the major findings of a 1999?2001 assessment of water quality in the Yellowstone River Basin. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. This report is intended for individuals working with water-resource issues in Federal, State, or local agencies, universities, public interest groups, or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report also is for individuals who wish to know more about the quality of streams and ground water in areas near where they live, and how that water quality compares to the quality of water in other areas across the Nation. The water-quality conditions in the Yellowstone River Basin summarized in this report are discussed in detail in other reports that can be accessed from http://wy.water.usgs.gov/YELL/index.htm. Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented in this report, in addition to reports in this series from other basins, can be accessed from the national NAWQA Web site (http://water.usgs.gov/nawqa).

Circular↗
USGS2003

Water quality in the Northern Rockies Intermontane basins, Idaho, Montana, and Washington, 1999-2001

This report contains the major findings of a 1999–2001 assessment of water quality in the Northern Rockies Intermontane Basins. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. This report is intended for individuals working with water-resource issues in Federal, State, or local agencies, universities, public interest groups, or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams and ground water in areas near where they live, and how that water quality compares to the quality of water in other areas across the Nation. The water-quality conditions in the Northern Rockies Intermontane Basins summarized in this report are discussed in detail in other reports that can be accessed from (http://id.water.usgs.gov/nrok/index.html). Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented in this report in addition to reports in this series from other basins can be accessed from the national NAWQA Web site (http://water.usgs.gov/nawqa).

Idaho;Montana;Washington↗
USGS1952

Water resources of the Lake Erie shore region in Pennsylvania

An abundant supply of water is available to the Lake Erie Shore region in Pennsylvania. Lake i£rie furnishes an almost inexhaustible supply of water of satisfactory chemical quality. Small quantities of water are available from small streams in the area and from the ground. A satisfactory water supply is one of the factors that affect the economic growth of a region. Cities and towns must have adequate amounts of pure water for human consumption. Industries must have suitable water ih sufficient quantities for all purposes. In order to assure. success and economy, the development of water resources should be based on adequate knowledge of the quantity and quality of the water. As a nation, we can not afford to run the risk of dissipating our resources, especially in times of national emergency, by building projects that are not founded on sound engineering and adequate water-resources information. The purpose of this report is to summarize and interpret all available water-resources information for the Lake Erie Shore region in Pennsylvania. The report will be useful for initial guidance in the location or expansion of water facilities for defense and nondefense industries and the municipalities upon which they are dependent. It will also be useful in evaluating the adequacy of the Geological Survey's part of the basic research necessary to plan the orderly development of the water resources of the Lake Erie Shore region. Most of the data contained inthis report have been obtained'by the U. S. Geological Survey in cooperation with the Pennsylvania Department of Forests and Waters, the Pennsylvania Department of Internal Affairs, and the Pennsylvania State Planning Board, Department of Commerce. The Pennsylv~nia Department of Health furnished information on water pollution. The report was prepared in the Water Resources Division of the U. S. Geological Survey b:y John W. Mangan (Surface Water). Donald W. VanTuyl (Ground Water). and Walter F. White, Jr. (Quality of Water), under the general direction of C. G. Paulsen, chief hydraulic engineer.

Circular↗
USGS2007

Abstracts of the Annual Meeting of Planetary Geologic Mappers, Tucson, AZ 2007

Introduction Report of the Annual Mappers Meeting Planetary Science Institute Tucson, Arizona June 28 and 29, 2007 Approximately 22 people attended this year's mappers meeting, and many more submitted abstracts and maps in absentia. The 2007 meeting was convened by Tracy Gregg, Les Bleamaster, Steve Saunders, and Ken Tanaka and was hosted by David Crown and Les Bleamaster of the Planetary Science Institute (PSI) in Tucson, Arizona. Oral presentations and poster discussions took place on Thursday, June 28 and Friday, June 29. This year's meeting also included a unique opportunity to visit the operations centers of two active Mars missions; field trips to the University of Arizona took place on Thursday and Friday afternoons. Outgoing Geologic Mapping Subcommittee (GEMS) chairperson, Tracy Gregg, commenced the meeting with an introduction and David Crown followed with a discussion of logistics and the PSI facility; Steve Saunders (Planetary Geology and Geophysics Discipline Scientist) then provided a brief program update. Science presentations kicked off with Venus mapper Vicki Hansen and graduate students Eric Tharalson and Bhairavi Shankar of the University of Minnesota, Duluth, showing a 3-D animation of the global distribution of tesserae and discussing the implications, a progress report for V-45 quadrangle mapping, and a brief discussion of circular lows. Les Bleamaster (PSI) followed with a progress report on mapping of the V-50 quadrangle and the 1:10M Helen Planitia quadrangle. David Crown (PSI) concluded the Venus presentations with a discussion of progress made on the V-30 quadrangle. The remainder of Thursday's presentations jumped around the Solar System including Mars, Io, and Earth. Ken Tanaka of the U.S. Geological Survey (USGS) began the afternoon with a general discussion of the status of the planetary mapping program at USGS. Buck Janes (University of Arizona) provided background information about the Mars Odyssey Gamma Ray Spectrometer (GRS) and presented some new element maps, which may be useful for geologic mapping. Dave Williams of Arizona State University reported on the progress of his global Io map and James Dohm (University of Arizona) discussed results of terrestrial remote mapping studies. Thursday afternoon, the mappers were given a tour of the High Resolution Imaging Science Experiment (HiRISE) operations facility and were given some basic information about how the images are obtained, processed, and publicly released. With official GEMS transition completed at lunch on Thursday, incoming GEMS chair Leslie Bleamaster took the reigns of Friday's meeting. Science presentations began with Ken Tanaka discussing 1:20M-scale global and 1:2M-scale polar mapping of Mars. Jim Zimbelman (Smithsonian Institution) described his 1:1M Medusae Fossae map (MC-8 SE), which is nearing completion, and new mapping (MC-16 NW and MC-23 NW) to further evaluate the Medusae Fossae. Brent Garry, also of the Smithsonian Institution, presented work on Ascraeus Mons. Peter Mouginis-Mark (University of Hawai`i) reported progress on his 1:200K and larger maps of Tooting crater and of the Olympus Mons summit caldera. Laszlo Keszthelyi (USGS) presented mapping of Athabasca Valles, with much of the credit going to Windy Jaeger. Jim Skinner (USGS) introduced a new mapping project including nine MTM quadrangles in the Utopia Planitia region. Tracy Gregg finished off the day's science presentations with discussion of Hesperia Planum. After discussion was complete, the group once again traveled to the University of Arizona - this time for a tour of the Mars Phoenix operations center. Principal Investigator Peter Smith beamed as he led mappers through the multi-million dollar facility. A main topic of discussion throughout the entire meeting was that of nomenclature, specifically how to classify the individual depressions at the tops of volcanoes. Paterae, as has been used for Mars, Venus, and Io, was suggested, but i

Open-File Report↗
USGS1996

Level II scour analysis for Bridge 5 (IRASTH00010005) on Town Highway 1, crossing Lords Creek, Irasburg, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure IRASTH00010005 on town highway 1 crossing Lords Creek, Irasburg, 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 VTAOT files, was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the New England Upland section of the New England physiographic province of north-central Vermont in the town of Irasburg. The 15.1-mi 2 drainage area is in a predominantly rural and forested basin with some pasture land mainly along the valley bottom. In the vicinity of the study site, the bank vegetation coverage is pasture grasses. In the study area, Lords Creek has a meandering channel with a slope of approximately 0.0026 ft/ft, an average channel top width of 32 ft and an average channel depth of 3 ft. The channel bed material ranged from gravel (D50 is 46.6 mm or 0.153 ft) to silt/clay material (D 50 of 1.006 mm or 0.0033 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 5 and 6, 1994, indicated that the reach was laterally unstable. The town highway 1 crossing of Lords Creek is a 65-ft-long, two-lane bridge consisting of one 61-foot, steel-beam span (Vermont Agency of Transportation, written communication, August 2, 1994). The bridge is supported by vertical, concrete abutments on wooden piles driven to bedrock with no wingwalls. Each abutment wall has a spill-through slope protected with type-2 stone fill (less than 36 inches diameter). The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway is 15 degrees. 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 2.4 to 4.6 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.2 to 9.8 ft. The worst-case abutment scour also 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.

Vermot↗
USGS1996

Level II scour analysis for Bridge 46 (ENOSVT01080046) on State Route 108, crossing an Unnamed "The Branch" Tributary, Enosburg, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure ENOSVT01080046 on State Route 108 crossing an unnamed "The Branch" tributary, Enosburg, 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 north-central Vermont. The 1.55-mi 2 drainage area is in a predominantly rural, pasture and forested basin. In the vicinity of the study site, the surface cover is pasture. In the study area, this unnamed "The Branch" tributary has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 45 ft and an average channel depth of 3 ft. The predominant channel bed material is gravel and cobbles with a median grain size (D 50 ) of 42.4 mm (0.139 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 29, 1995, indicated that the reach was laterally unstable. Block failure slumping of bank material was evident at an upstream cut-bank and another minor cut-bank was noted downstream. The State Route 108 crossing of this unnamed "The Branch" tributary is a 25-ft-long, twolane bridge consisting of one 22-foot concrete span (Vermont Agency of Transportation, written communication, March 8, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 10 degrees to the opening while the opening-skew-to-roadway is zero degrees. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) at the downstream end of the downstream left wingwall. 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 0.3 to 0.5 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.0 to 8.0 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). 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↗
USGS1996

Level II scour analysis for Bridge 32 (BRNATH00470032) on Town Highway 47, crossing Locust Creek, Barnard, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure BRNATH00470032 on town highway 47 crossing Locust Creek, Barnard, 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 of central Vermont in the town of Barnard. The 6.26-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the banks have dense woody vegetation coverage except for the upstream right bank, which is grass and brush covered. In the study area, Locust Creek has an incised, sinuous channel with a slope of approximately 0.029 ft/ft, an average channel top width of 44 ft., and an average channel depth of 5 ft. The predominant channel bed material is gravel and cobbles (D50 is 91.7 mm or 0.301 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 12, 1994, indicated that the reach was stable. The town highway 47 crossing of Locust Creek is a 28-ft-long, one-lane bridge consisting of one 25-foot span concrete slab superstructure (Vermont Agency of Transportation, written commun., August 23, 1994). The bridge is supported by vertical, concrete abutments with concrete wingwalls. The channel is skewed approximately 10 degrees to the opening while the opening-skew-to-roadway is 35 degrees. The scour protection measures at the site were type-2 stone fill (less than 36 inches diameter) on the banks upstream, the upstream wingwalls, the downstream right wingwall, and the downstream right bank. The downstream left wingwall and left bank are protected with type-3 stone fill (less than 48 inches diameter). 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, 1993). 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 these computed results follow. Contraction scour for all modelled flows ranged from 1.4 to 2.2 feet. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 10.3 to 15.0 feet. The worst-case abutment scour also 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 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, 1993, 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↗
USGS1996

Level II scour analysis for Bridge 13 (POMFTH00020013) on Town Highway 2, crossing Barnard Brook, Pomfret, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure POMFTH00020013 on town highway 2 crossing Barnard Brook, Pomfret, 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 study 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 can be found in Appendix D. The site is in the New England Upland section of the New England physiographic province of east-central Vermont in the town of Pomfret. The 7.98-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is primarily field grasses with some brush on the immediate banks. In the study area, Barnard Brook has an incised, sinuous channel with a slope of approximately 0.006 ft/ft, an average channel top width of 32 ft and an average channel depth of 4 ft. The predominant channel bed materials are gravel and cobbles with a median grain size (D 50 ) of 51.0 mm (0.167 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 15, 1994, indicated that the reach was stable. The town highway 2 crossing of Barnard Brook is a 23-ft-long, two-lane bridge consisting of one 20-foot concrete span (Vermont Agency of Transportation, written communication, August 22, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 30 degrees to the opening while the opening-skew-toroadway is 0 degrees. Scour, 2.5 ft deeper than the mean thalweg depth, was observed along the left abutment during the Level I assessment. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) along the base and upstream of the upstream left wingwall. 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 0.0 to 1.5 ft. The worst-case contraction scour occurred at the 100-year discharge. Abutment scour ranged from 7.2 to 12.6 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). 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↗
USGS1996

Level II scour analysis for Bridge 59 (NWPCVT01050059) on State Route 105 crossing an unnamed Mud Creek Tributary, Newport, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure NWPCVT01050059 on state route 105 crossing an unnamed Mud Creek tributary, Newport, 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 of north-central Vermont in the town of Newport. The 9.18-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture while the immediate banks are brush covered with some trees. In the study area, this unnamed Mud Creek tributary has an incised, sinuous channel with a slope of approximately 0.005 ft/ft, an average channel top width of 42 ft and an average channel depth of 5 ft. The predominant channel bed materials are gravel and cobbles with a median grain size (D 50 ) of 54.1 mm (0.178 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 21, 1994, indicated that the reach was stable. The state route 105 crossing of an unnamed Mud Creek tributary is a 33-ft-long, two-lane bridge consisting of one 29-foot concrete-slab span (Vermont Agency of Transportation, written communication, August 5, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 15 degrees to the opening and the opening-skew-to-roadway is 15 degrees. Scour protection measures at the site were type-2 stone fill (less than 36 inches diameter) on each bank upstream and both upstream wingwalls. The downstream wingwalls are protected by remnant abutment walls from a previous structure. 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, 1993). 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 0.2 to 0.5 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 5.2 to 16.6 ft. The worst-case abutment scour also 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 7 (CHESTH00030007) on Town Highway 3, crossing the South Branch Williams River, Chester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CHESTH00030007 on Town Highway 3 which is also State Route 35 crossing the South Branch 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 in the New England Upland section of the New England physiographic province in southern Vermont. The 10.4-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture on the upstream right bank while the immediate bank has some trees. Downstream of the bridge and the upstream left bank are forested. In the study area, the South Branch Williams River has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 65 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 70.5 mm (0.231 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 26, 1996, indicated that the reach was laterally unstable. There are cutbanks on both the left and right banks alternating with point bars in the upstream reach. The Town Highway 3 (VT 35) crossing of the South Branch Williams River is a 74-ft-long, two-lane bridge consisting of one 72-foot steel-beam span (Vermont Agency of Transportation, written communication, March 30, 1995). The bridge is supported by spill- through abutments. The channel is skewed approximately 5 degrees to the opening and the opening-skew-to-roadway is also 5 degrees. Three channel scour holes 1.0 ft deeper than the mean thalweg depth were observed during the Level I assessment in the upstream reach. There are no scour protection measures at the site. 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 0.4 ft. The worst-case contraction scour occurred at the 100-year. Abutment scour ranged from 4.1 to 15.5 ft. The worst-case abutment scour occurred at the 500-year. 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↗
USGS1996

Level II scour analysis for Bridge 23 (HARDTH00530023) on Town Highway 53, crossing Haynesville Brook, Hardwick, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure HARDTH00530023 on Town Highway 53 crossing Haynesville Brook, Hardwick, 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 north-central Vermont. The 14.2-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the predominate surface cover consists of field grasses except for the upstream left bank with is brush covered. In the study area, Haynesville Brook has a sinuous channel with a slope of approximately 0.004 ft/ft, an average channel top width of 39 ft and an average channel depth of 2 ft. Stream-bed material at the site ranged from silt to gravel with a median grain size (D50) of 49.9 mm (0.164ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 27, 1995, indicated that the reach was laterally unstable. Channel scour in both the upstream and downstream reaches as well as irregular point bars and cut banks and upstream anabranching led to this assessment. The Town Highway 53 crossing of Haynesville Brook is a 33-ft-long, one-lane bridge consisting of one 26-foot steel-beam span (Vermont Agency of Transportation, written communication, March 24, 1994). The bridge is supported by vertical, concrete abutments with no wingwalls. The concrete may be facing over the original stone abutments. Sheet piling has been driven around the base of each abutment and is filled with concrete. The channel is skewed approximately 10 degrees to the opening; the opening-skew-to-roadway is also 10 degrees. 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 0.0 to 2.0 ft. The worst-case contraction scour occurred at the 100-year discharge. Abutment scour ranged from 7.0 to 12.9 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). 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 23 (GLOVTH00410023) on Town Highway 41, crossing Sherburne Brook, Glover, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure GLOVTH00410023 on Town Highway 41 crossing Sherburne Brook, Glover, 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 northern Vermont. The 2.57-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is primarily forest with small areas of lawn and a home on the right overbank and a gravel roadway along the upstream left bank. In the study area, Sherburne Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 33 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 57.3 mm (0.188 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 24, 1994, indicated that the reach was stable. The Town Highway 41 crossing of Sherburne Brook is a 24-ft-long, one-lane bridge consisting of one 21-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, August 4, 1994). The opening length of the structure parallel to the bridge face is 20.3 ft. The bridge is supported by vertical, granite block abutments. The channel is skewed approximately 55 degrees to the opening while the measured opening-skew-to-roadway is 30 degrees. One foot of scour below the mean thalweg depth was observed along the right abutment undermining the abutment by 0.5 feet vertically. 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 0.4 to 0.8 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.6 to 7.2 ft. The worst-case abutment scour also 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↗
USGS1996

Level II scour analysis for Bridge 8 (BARTTH00020008) on Town Highway 2, crossing Roaring Brook, Barton, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure BARTTH00020008 on town highway 2 crossing Roaring Brook, Barton, 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 VTAOT files, was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the New England Upland section of the New England physiographic province of North-central Vermont in the town of Barton. The 9.89-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the banks have woody vegetation coverage except for the downstream left bank, which has a few trees and grass and brush coverage. In the study area, Roaring Brook has an incised, sinuous channel with a slope of approximately 0.019 ft/ft, an average channel top width of 35 ft and an average channel depth of 3 ft. The predominant channel bed material is gravel/cobble (D 50 is 49.1 mm or 0.161 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1994 indicated that the reach was laterally unstable. A cut-bank on the downstream right bank and overall channel configuration in the valley are indications of the lateral instability at this site. The town highway 2 crossing of Roaring Brook is a 30-ft-long, two-lane bridge consisting of one 26-foot span concrete T-beam type superstructure (Vermont Agency of Transportation, written communication, August 4, 1994). The bridge is supported by vertical, concrete abutments. The channel is skewed approximately 15 degrees to the opening while the opening-skew-to-roadway is zero degrees. A scour hole 2.5 ft deeper than the mean thalweg depth was observed near mid-channel downstream of the bridge during the Level I assessment. The only scour protection measure at the site was type-1 stone fill (less than 12 inches diameter) on the left upstream and downstream roadway embankments. 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 aggradation or degradation; 2) contraction scour (due to reduction in flow area caused by 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 scour depths for contraction and local scour and a summary of the results follows. Contraction scour for all modelled flows ranged from 1.4 to 2.8 feet and the worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.5 to 16.5 feet and 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). 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 16 (TROYTH00290016) on Town Highway 29, crossing Beetle Brook, Troy, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure TROYTH00290016 on Town Highway 29 crossing Beetle Brook, Troy, 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 north-central Vermont. The 8.70-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest. In the study area, Beetle Brook has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 42 ft and an average bank height of 3 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 61.9 mm (0.203 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 8, 1995, indicated that the reach was stable. The Town Highway 29 crossing of Beetle Brook is a 26-ft-long, one-lane bridge consisting of one 23-foot log-beam span (Vermont Agency of Transportation, written communication, March 7, 1995). The opening length of the structure parallel to the bridge face is 20.0 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 5 degrees to the opening while the measured opening-skew-toroadway is 10 degrees. A scour hole 1.2 ft deeper than the mean thalweg depth was observed along the failed downstream right wingwall during the Level I assessment. The scour counter-measures at the site included type-2 stone fill (less than 36 inches diameter) at the upstream end of the upstream right wingwall and at the downstream left wingwall. 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 1.8 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 9.2 to 13.4 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). 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↗
USGS1996

Level II scour analysis for Bridge 15 (BRIDTH00220015) on Town Highway 22, crossing Dailey Hollow Branch, Bridgewater, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure BRIDTH00220015 on town highway 22 crossing Dailey Hollow Branch, Bridgewater, 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 of central Vermont in the town of Bridgewater. The 1.73-mi2 drainage area is a predominantly rural and forested basin. In the vicinity of the study site, the left and right banks have dense tree cover. The upstream right bank of Dailey Hollow Branch is adjacent to town highway 22. In the study area, Dailey Hollow Branch has a sinuous channel with a slope of approximately 0.035 ft/ft, an average channel top width of 30 ft and an average channel depth of 4 ft. The predominant channel bed material is cobble with a median grain size (D50) of 108 mm (0.354 ft). The geomorphic assessment at the time of the Level I and Level II site visit on November 1 and 2, 1994, indicates that the reach is stable. The town highway 22 crossing of Dailey Hollow Branch is a 22-ft-long, one-lane bridge consisting of one 22-ft. steel-beam span (Vermont Agency of Transportation, written communication, August 24, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. Type-1 stone fill (less than 12 inches diameter) protects the left abutment, but it’s condition was reported as eroded. Type-2 stone fill (less than 36 inches diameter) protects the upstream left wingwall; it’s condition was reported as slumping.The channel is skewed approximately 40 degrees to the opening while the opening-skew-to-roadway is 0 degrees. 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, 1993). 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 0.2 ft. with the worst-case contraction scour occurring at the 500-year discharge. Abutment scour ranged from 4.2 to 6.4 ft. The worst-case abutment scour also 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, 1993, 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↗