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Examination of Direct Discharge Measurement Data and Historic Daily Data for Selected Gages on the Middle Mississippi River, 1861-2008

An examination of data from two continuous stage and discharge streamgages and one continuous stage-only gage on the Middle Mississippi River was made to determine stage-discharge relation changes through time and to investigate cause-and-effect mechanisms through evaluation of hydraulic geometry, channel elevation and water-surface elevation data. Data from discrete, direct measurements at the streamgages at St. Louis, Missouri, and Chester, Illinois, during the period of operation by the U.S. Geological Survey from 1933 to 2008 were examined for changes with time. Daily stage values from the streamgages at St. Louis (1861-2008) and Chester (1891-2008) and the stage-only gage at Cape Girardeau, Missouri (1896-2008), throughout the historic period of record also were examined for changes with time. Stage and discharge from measurements and stage-discharge relations at the streamgages at St. Louis and Chester indicate that stage for a given discharge has changed with time at both locations. An apparent increase in stage for a given discharge at increased flows (greater than flood stage) likely is caused by the raising of levees on the flood plains, and a decrease in stage for a given discharge at low flows (less than one-half flood stage) likely is caused by a combination of dikes in the channel that deepen the channel thalweg at the end of the dikes, and reduced sediment flux into the Middle Mississippi River. Since the 1960s at St. Louis, Missouri, the stage-discharge relations indicated no change or a decrease in stage for a given discharge for all discharges, whereas at Chester, Illinois, the stage-discharge relations indicate increasing stage for a given discharge above bankfull because of sediment infilling of the overflow channel. Top width and average velocity from measurements at a given discharge for the streamgage at St. Louis, Missouri, were relatively constant through time, with the only substantial change in top width resulting from the change in measurement location from the Municipal/MacArthur Bridge to the Poplar Street Bridge in 1968. The average bed elevation appeared to be lowering with time at both measurement locations at St. Louis. Flow in the Horse Island Chute overflow channel for the streamgage at Chester, Illinois had an effect on top width and average velocity from measurements, and this effect changed with time as the inflow channel to Horse Island Chute filled with sediment. Top width from measurements at a given discharge was consistent through time at the Chester streamgage when adjusted to remove the part of the flow through Horse Island Chute. Average velocity from measurements at a given discharge appears to be increasing with time, possibly as a result of a series of dikes built or extended in the channel immediately upstream from the Chester streamgage; however, the average bed elevation for all discharges less than bankfull at the Chester streamgage fluctuate around an average value from 1948 to 2000, and the fluctuations appear to be related to the occurrence of moderate and large floods. Daily stage and discharge values available for the streamgage at St. Louis, Missouri, from 1861 to 1932 display distinct, fixed relations that change slightly with time before operation by the U.S. Geological Survey, indicating daily discharge was obtained from the daily stage value during this timeframe. A sudden and substantial reduction of about 24 percent at the upper end of the ratings for discharge at a given stage occurred between 1932 and 1933 when the U.S. Geological Survey began operating the streamgage. This change likely is the result of the change to Price AA current meters from other, less-accurate methods used for discharge measurements before 1933. Based on modeling results for the Middle Mississippi River by the U.S. Army Corps of Engineers and the findings of this study, the accuracy of the historic record before 1933 is questionable, and needs to be examined further. The differ

Scientific Investigations Report↗

Enhancements to the Mississippi Embayment Regional Aquifer Study (MERAS) groundwater-flow model and simulations of sustainable water-level scenarios

Arkansas continues to be one of the largest users of groundwater in the Nation. As such, long-term planning and management are essential to ensure continued availability of groundwater and surface water for years to come. The Mississippi Embayment Regional Aquifer Study (MERAS) model was developed previously as a tool to evaluate groundwater availability within the Mississippi embayment, which encompasses much of eastern Arkansas where the majority of groundwater is used. The Arkansas Water Plan is being updated for the first time since 1990 and serves as the State’s primary, comprehensive water-resources planning and guidance document. The MERAS model was selected as the best available tool for evaluation of specific water-use pumping scenarios that are currently being considered by the State of Arkansas. The model, developed as part of the U.S. Geological Survey Groundwater Resources Program’s assessment of the Nation’s groundwater availability, is proving to be invaluable to the State as it works toward development of a sustained yield pumping strategy. One aspect of this investigation was to evaluate multiple methods to improve the match of observed to simulated groundwater levels within the Mississippi River Valley alluvial and middle Claiborne (Sparta) aquifers in the MERAS model. Five primary methods were evaluated: (1) explicit simulation of evapotranspiration (ET), (2) upgrade of the Multi-Node Well (MNW2) Package, (3) geometry improvement within the Streamflow Routing (SFR) Package, (4) parameter estimation of select aquifer properties with pilot points, and (5) modification of water-use estimates. For the planning purposes of the Arkansas Water Plan, three scenarios were developed to evaluate potential future conditions: (1) simulation of previously optimized pumping values within the Mississippi River Valley alluvial and the middle Claiborne aquifers, (2) simulated prolonged effects of pumping at average recent (2000–5) rates, and (3) simulation of drawdown constraints on most pumping wells. The explicit simulation of ET indicated little, if any, improvement of model fit at the expense of much longer simulation time and was not included in further simulations. Numerous attempts to fully utilize the MNW2 Package were unsuccessful in achieving model stability, though modifications made to the water-use dataset remained intact. Final improvements in the residual statistics may be attributed to a single method, or a cumulative effect of all other methods (geometry improvement with the SFR Package, parameter estimation with pilot points, and modification of water-use estimates) attempted. The root mean squared error (RMSE) for all observations in the model is 22.65 feet (ft) over a range in observed hydraulic head of 741.66 ft. The RMSE for water-level observations in the Mississippi River Valley alluvial aquifer is 14.14 ft (an improvement of almost 3 ft) over a range in observed hydraulic head of 297.25 ft. The RMSE for the Sparta aquifer is 32.02 ft (an improvement of approximately 3 ft) over a range in observed hydraulic head of 634.94 ft. Three scenarios were developed to utilize a steady-state version of the MERAS model. Scenario 1 was developed to use pumping values resulting from the optimization of baseline rates (typically 1997 pumping rates) from previous optimization modeling of the alluvial aquifer and the Sparta aquifer. Scenario 2 was developed to evaluate the prolonged effects of pumping from the alluvial aquifer at recent pumping rates. Scenario 3A was designed to evaluate withdrawal limits from the alluvial aquifer by utilizing drawdown constraints equal to an altitude of approximately 50 percent of the predevelopment saturated thickness of the alluvial aquifer or 30 ft above the bottom of the alluvial aquifer, whichever was greater. The results of scenario 1 indicate large water-level declines throughout the area of the alluvial aquifer, regardless of the substitution of the optimized pumping values from earlier model simulations. The results of scenario 2 also indicate large areas of water-level decline, as compared to half of the saturated thickness, throughout the alluvial aquifer. The results of scenario 3A reveal some effects from the inclusion of multiple aquifers in a single simulation. The initial configuration of scenario 3A resulted in water levels well below the defined drawdown constraint, and some areas of depleted aquifer (water levels that are near or below the bottom of the aquifer) in east-central Arkansas. A fourth simulation (scenario 3B) was configured to apply the same drawdown constraints from the alluvial aquifer wells to the Sparta aquifer wells in the depleted area. These drawdown constraints reduce leakage from the alluvial aquifer to the underlying Sparta aquifer. This configuration did not produce depleted areas within the alluvial aquifer. Scenarios 3A and 3B indicate that even when pumping is limited in the alluvial aquifer, water levels in the alluvial aquifer may continue to decline in some areas because of pumping in the underlying Sparta aquifer.

Arkansas↗

Annual and average estimates of water-budget components based on hydrograph separation and PRISM precipitation for gaged basins in the Appalachian Plateaus Region, 1900-2011

As part of the U.S. Geological Survey’s Groundwater Resources Program study of the Appalachian Plateaus aquifers, annual and average estimates of water-budget components based on hydrograph separation and precipitation data from parameter-elevation regressions on independent slopes model (PRISM) were determined at 849 continuous-record streamflow-gaging stations from Mississippi to New York and covered the period of 1900 to 2011. Only complete calendar years (January to December) of streamflow record at each gage were used to determine estimates of base flow, which is that part of streamflow attributed to groundwater discharge; such estimates can serve as a proxy for annual recharge. For each year, estimates of annual base flow, runoff, and base-flow index were determined using computer programs—PART, HYSEP, and BFI—that have automated the separation procedures. These streamflow-hydrograph analysis methods are provided with version 1.0 of the U.S. Geological Survey Groundwater Toolbox, which is a new program that provides graphing, mapping, and analysis capabilities in a Windows environment. Annual values of precipitation were estimated by calculating the average of cell values intercepted by basin boundaries where previously defined in the GAGES–II dataset. Estimates of annual evapotranspiration were then calculated from the difference between precipitation and streamflow.

Appalachian Plateaus Region↗

Land-cover change in the Lower Mississippi Valley, 1973-2000

The Land Cover Trends is a research project focused on understanding the rates, trends, causes, and consequences of contemporary United States land-use and land-cover change. The project is coordinated by the Geographic Analysis and Monitoring Program of the U.S. Geological Survey (USGS) in conjunction with the U.S. Environmental Protection Agency (EPA) and the National Aeronautics and Space Administration (NASA). Using the EPA Level III ecoregions as the geographic framework, scientists process geospatial data collected between 1973 and 2000 were processed to characterize ecosystem responses to land-use changes. The 27-year study period was divided into four temporal periods: 1973 to1980, 1980 to 1986, 1986 to 1992, 1992 to 2000 and overall from 1973 to 2000. General land-cover classes for these periods were interpreted from Landsat Multispectral Scanner, Thematic Mapper, and Enhanced Thematic Mapper Plus imagery to categorize and evaluate land-cover change using a modified Anderson Land Use Land Cover Classification System (Anderson and others, 1976) for image interpretation. The rates of land-cover change were estimated using a stratified, random sampling of 10-kilometer (km) by 10-km blocks allocated within each ecoregion. For each sample block, satellite images were used to interpret land-cover change. The sample block data then were incorporated into statistical analyses to generate an overall change matrix for the ecoregion. These change statistics are applicable for different levels of scale, including total change for the individual sample blocks and change estimates for the entire ecoregion.

Open-File Report↗

Hydrogeology of the Southeastern Coastal Plain aquifer system in Mississippi, Alabama, Georgia, and South Carolina

The Southeastern Coastal Plain aquifer system consists of a thick sequence of unconsolidated to poorly consolidated Cretaceous and Tertiary rocks that extend from Mississippi to South Carolina. Four regional sand and gravel aquifers are separated by three regional confining units of clay, shale, and chalk that do not conform everywhere to stratigraphic boundaries. The change in geologic facies is the most important factor controlling the distribution of transmissivity within the aquifer system.

Alabama, Georgia, Mississippi, South Carolina↗

Trends In Nutrient and Sediment Concentrations and Loads In Major River Basins of the South-Central United States, 1993-2004

Nutrient and sediment data collected at 115 sites by Federal and State agencies from 1993 to 2004 were analyzed by the U.S. Geological Survey to determine trends in concentrations and loads for selected rivers and streams that drain into the northwestern Gulf of Mexico from the south-central United States, specifically from the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf Basins. Trends observed in the study area were compared to determine potential regional patterns and to determine cause-effect relations with trends in hydrologic and human-induced factors such as nutrient sources, streamflow, and implementation of best management practices. Secondary objectives included calculation of loads and yields for the study period as a basis for comparing the delivery of nutrients and sediment to the northwestern Gulf of Mexico from the various rivers within the study area. In addition, loads were assessed at seven selected sites for the period 1980-2004 to give hydrologic perspective to trends in loads observed during 1993-2004. Most study sites (about 64 percent) either had no trends or decreasing trends in streamflow during the study period. The regional pattern of decreasing trends in streamflow during the study period appeared to correspond to moist conditions at the beginning of the study period and the influence of three drought periods during the study period, of which the most extreme was in 2000. Trend tests were completed for ammonia at 49 sites, for nitrite plus nitrate at 69 sites, and for total nitrogen at 41 sites. For all nitrogen constituents analyzed, no trends were observed at half or more of the sites. No regional trend patterns could be confirmed because there was poor spatial representation of the trend sites. Decreasing trends in flow-adjusted concentrations of ammonia were observed at 25 sites. No increasing trends in concentrations of ammonia were noted at any sites. Flow-adjusted concentrations of nitrite plus nitrate decreased at 7 sites and increased at14 sites. Flow-adjusted concentrations of total nitrogen decreased at 2 sites and increased at 12 sites. Improvements to municipal wastewater treatment facilities contributed to the decline of ammonia concentrations at selected sites. Notable increasing trends in nitrite plus nitrate and total nitrogen at selected study sites were attributed to both point and nonpointsources. Trend patterns in total nitrogen generally followed trend patterns in nitrite plus nitrate, which was understandable given that nitrite plus nitrate loads generally were 70-90 percent of the total nitrogen loads at most sites. Population data were used as a surrogate to understand the relation between changes in point sources and nutrient trends because data from wastewater treatment plants were inconsistent for this study area. Although population increased throughout the study area during the study period, there was no observed relation between increasing trends in nitrogen in study area streams and increasing trends in population. With respect to other nitrogen sources, statistical results did suggest that increasing trends in nitrogen could be related to increasing trends in nitrogen from either commercial fertilizer use and/or land application of manure. Loads of ammonia, nitrite plus nitrate, and total nitrogen decreased during the study period, but some trends in nitrogen loads were part of long-term decreases since 1980. For example, ammonia loads were shown to decrease at nearly all sites over the past decade, but at selected sites, these decreasing trends were part of much longer trends since 1980. The Mississippi and Atchafalaya Rivers contributed the highest nitrogen loads to the northwestern Gulf of Mexico as expected; however, nitrogen yields from smaller rivers had similar or higher yields than yields from the Mississippi River. Trend tests were completed for orthophosphorus at 34 sites and for total phosphorus at 52 sites. No trends were observed in abo

Scientific Investigations Report↗

Simulation of projected water demand and ground-water levels in the Coffee Sand and Eutaw-McShan aquifers in Union County, Mississippi, 2010 through 2050

Ground water from the Eutaw-McShan and the Coffee Sand aquifers is the major source of supply for residential, commercial, and industrial purposes in Union County, Mississippi. Unbiased, scientifically sound data and assessments are needed to assist agencies in better understanding and managing available water resources as continuing development and growth places more stress on available resources. The U.S. Geological Survey, in cooperation with the Tennessee Valley Authority, conducted an investigation using water-demand and ground-water models to evaluate the effect of future water demand on groundwater levels. Data collected for the 12 public-supply facilities and the self-supplied commercial and industrial facilities in Union County were used to construct water-demand models. The estimates of water demand to year 2050 were then input to a ground-water model based on the U.S. Geological Survey finite-difference computer code, MODFLOW. Total ground-water withdrawals for Union County in 1998 were estimated as 2.85 million gallons per day (Mgal/d). Of that amount, municipal withdrawals were 2.55 Mgal/d with about 1.50 Mgal/d (59 percent) delivered to residential users. Nonmunicipal withdrawals were 0.296 Mgal/d. About 80 percent (2.27 Mgal/d) of the total ground-water withdrawal is produced from the Eutaw-McShan aquifer and about 13 percent (0.371 Mgal/d) from the Coffee Sand aquifer. Between normal- and high-growth conditions, total water demand could increase from 72 to 131 percent (2.9 Mgal/d in 1998 to 6.7 Mgal/d in year 2050) with municipal demand increasing from 77 to 146 percent (2.6 to 6.4 Mgal/d). Increased pumping to meet the demand for water was simulated to determine the effect on water levels in the Coffee Sand and Eutaw- McShan aquifers. Under baseline-growth conditions, increased water use by year 2050 could result in an additional 65 feet of drawdown in the New Albany area below year 2000 water levels in the Coffee Sand aquifer and about 120 feet of maximum drawdown in the Eutaw-McShan aquifer. Under normal-growth conditions, increased water use could result in an additional 65 feet of drawdown in the New Albany area below year 2000 water levels in the Coffee Sand aquifer and about 135 feet of maximum drawdown in the Eutaw-McShan aquifer. Under high-growth conditions, increased water use could result in 75 feet of drawdown in the New Albany area below year 2000 water levels in the Coffee Sand aquifer and about 190 feet of maximum drawdown in the Eutaw-McShan aquifer. The resulting highgrowth projected water level for the year 2050 at the center of the drawdown cone in the New Albany area is between 450 and 500 feet above the top of the Eutaw-McShan aquifer.

Mississippi↗

Slowing of coastal subsidence is good news for restoration of Louisiana's wetlands

Every year, volunteers use thousands of discarded Christmas trees to build brush fences in the coastal waters of Louisiana. The fences slow down waves and trap sediment, allowing aquatic vegetation to take root in the still water and stimulating the growth of new marsh. This is one of many efforts to counteract wetland loss (the loss of saline, brackish, intermediate, and freshwater marshes) that has plagued coastal Louisiana since the mid-20th century. U.S. Geological Survey (USGS) scientists recently announced good news for Louisiana's coastal-restoration projects: using a combination of historical and recently released data, they discovered that subsidence of coastal land in the Mississippi River delta plain appears to have slowed considerably since the 1990s. This discovery means that new marshlands created by the Christmas tree program and other restoration projects may persist—that is, stay above sea level—longer than previously thought.

Louisiana↗

Water resources of the Minneapolis-St. Paul area, Minnesota

The water supply of the Minneapolis-St. Paul area is adequate to satisfy present requirements and requirements for many years to come if the area continues to develop at about the present rate. The flow of -the Mississippi River at the Twin Cities is more than sufficient to meet the demands of the water-supply systems of Minneapolis and St. Paul. The lowest momentary flow during the period 1931-51 was more than twice the present combined maximum demand of Minneapolis and St. Paul. The lake storage of the St. Paul system combined with possible regulations by the Mississippi River headwater reservoir system, in case of an emergency, provides a reserve supply ample to meet a greatly expanded demand. The lowest average daily flow of the Mississippi River at the intakes of the Minneapolis and St. Paul water supply was 389 mgd (602 cfs), The flow at the water supply intakes has been less than 452 mgd (700 cfs) for not more than 6 consecutive days. Except for the Mississippi River, the streams in the Twin Cities area have not been extensively developed for water supply. The only known use of them for water supply is for the steam-electric. generating plant on the Minnesota River at Savage. Thus, the St. Croix River, within 12 miles on the east, the Minnesota River entering the Twin Cities from the southwest, the Vermilion within 12 miles on the south, and the Crow River within 25 miles on the west offer untapped supplies for industrial and municipal uses. Many water-bearing formations occur in the area. A blanket of glacial deposits, as much as 400 feet thick, covers the area. Small domestic ground-water supplies can be developed practically everywhere in the glacial deposits, and larger industrial supplies can be obtained by exploring and testing. Below the glacial materials is a thick series of rock formations including several prolific sandstone aquifers. The formations dip toward the center of the area forming an artesian basin. The estimated average daily withdrawal of ground water from all aquifers in the area is about 90 mgd. Practically all the communities that are not supplied by the Minneapolis or St. Paul water-supply systems obtain their water from wells. Where many large-capacity wells have been concentrated in relatively small areas, there has been a great lowering of artesian pressures. However, there are large areas, distant from the centers of concentrated pumping, which are favorable for the development of additional ground water. With an adequate program of exploration and testing to determine precisely the geologic and hydrologic characteristics of the waterbearing formations, it is likely that large additional supplies of ground water can be developed for municipal and industrial uses. Both Minneapolis and St. Paul obtain their municipal water supplies from the Mississippi River above the TwinCities and are thus assured of a large supply that is not subject to contamination by industrial wastes and sewage effluents, Treatment at municipal plants for both cities provides water for diversified industrial use and for domestic use that meets U. S. Public Health Service drinking water standards., The treated water is remarkably uniform in chemical composition throughout the year and is virtually free of all color, iron, manganese, and turbidity. Currently, (1952). the two supplies are softened to about 75 ppm (as CaC03), which is an average reduction of about 55 percent in hardness of river water. The dissolvedsolids content of the treated water for St. Paul currently (1952) averages about 100 ppm; the dissolved-solids content of the Minneapolis water is slightly higher. As a matter of further interest to industrial consumers, temperatures of the untreated river water, which is only slightly altered at the Minneapolis treatment plant, averages less than 60 F for about 8 months of the year and is less than 40 F for 4 winter months. The Mississippi River as it enters the Twin Cities is moderately mineralized, averaging 241 ppm dissolved solids and 179 ppm hardness during the period 1940-49, Average turbidity is very low and silica is moderately low, but the quantities of iron and color in solution are relatively high. Color increases markedly during the period March to July in response to an increase in streamflow. The average chemical composition of the water has remained virtually unchanged except for seasonal variations since 1907. Data collected by the Minneapolis-St. Paul Sanitary District have shown improved sanitary conditions of the river at the Twin Cities lock and dam since the sewage plant went into operation in 1939. The Minnesota River is more than twice as mineralized and hard as the Mississippi River, and it exerts a noticeable effect on the chemical and sanitary quality of the Mississippi River at St. Paul. Other principal tributary streams to the Mississippi River, including Crow River, Vermilion River, and Bassett Creek, were sampled during the 1952 flood season, at which time they were of the calcium-bicarbonate type, more dilute, and of lower hardness than the Minnesota River. Lake waters in the Twin Cities area generally are less mineralized than those of the streams. Waters from the drift deposits and bedrock formations overlying the Hinckley sandstone are hard and calcareous and generally contain troublesome quantities of iron. Regular treatment is required of some public-supply wells for removal of iron encrustations. Water fr.om these sources generally exceeds 300 ppm hardness, but in some places the St. Peter sandstone and St. Lawrence formation yield water of better quality. The Hinckley sandstone yields the best quality ground-water because of its comparatively lower hardness and uniform temperature (about 52 F). However, the average hardness of the treated municipal supplies of St. Paul and Minneapolis is considerably less than water from the Hinckley.

Minnesota↗

Bedrock geology of the Paducah 1° x 2° CUSMAP quadrangle, Illinois, Indiana, Kentucky, and Missouri

The Paducah 1° x 2° quadrangle (hereafter referred to as the Paducah quadrangle) encompasses the eastern flank of the Ozark dome, the southern end of the Illinois Basin, and the northern end of the Mississippi Embayment. Resting on Proterozoic basement, sedimentary rocks of Cambrian through Permian age in the Illinois Basin and Ozark dome are overlapped by weakly lithified Cretaceous, Paleocene, Eocene, and Pliocene strata in the embayment. This is one of the most intensely faulted areas of the North American Midcontinent. A Proterozoic crustal terrane boundary (coincident with part of the Ste. Genevieve fault zone) and a failed intracratonic rift (Reelfoot rift and Rough Creek graben) have been reactivated repeatedly under various stress fields from Proterozoic through late Tertiary times.

Illinois, Indiana, Kentucky, Missouri↗

Mississippi carbonate shelf margins, western United States

Regional linear carbonate shelf margins, or stratigraphic reefs, are postulated to have developed during Mississippian time along the eastern flank of the Cordilleran miogeosyncline in the Western United States. These shelf margins are analogous to well-documented ancient and modern geologic counterparts, such as the Guadalupian reef of the West Texas Permian basin, the Lower Cretaceous Edwards shelf margin of the Gulf Coast, and the modern Florida reef tract-Straits of Florida province. Two Mississippian shelf margins are believed to have existed: The lower one developed as an integral part of a widespread carbonate depositional complex of Kinderhookian through early Meramecian age; the upper shelf margin developed west of the earlier stratigraphic reef as part of a regional carbonate depositional complex of middle Meramecian to late Chesterian age. Evidence for both shelf margins consists of (1) a linear physical barrier, (2) restricted sediments in the shelf interior, (3) abrupt basinward thinning of sediments and basin-starvation just seaward of the shelf edge, (4) profound fades-changes coincident with the basinward thinning from light-colored, skeletal, shelf carbonate rocks to dark, fine-grained, silty, basinal carbonate rocks, and (5) the consistent regional occurrence of the first four patterns. Seaward topographic relief along the front edge of the lower shelf margin was probably about 200-400 m, and maximum relief along the central sector of the upper shelf margin may have approached 1,000 m.

Arizona, California, Colorado, Idaho, Montana, Nev↗

Results of qualification tests on water-level sensing instruments, 1986

This report presents to users of hydrological instrumentation and U.S. Geological Survey procurement personnel a list of instruments that have met or exceeded the Survey 's minimum performance requirements for water level sensing instruments. The Hydrologic Instrumentation Facility at the National Space Technology Laboratories, Mississippi conducted qualification tests on four instrument systems. The data collected are summarized, brief system descriptions are given, qualification testing purposes and procedures are summarized, and results are given for each of the three systems that met performance requirements. The fourth system was returned to the manufacturer , because in preliminary testing the instrument system did not perform properly according to the manufacturer 's operating procedures. As a result of the qualification tests, the three systems that met performance requirements have been included on the Survey 's Qualified Products List. (USGS)

Open-File Report↗

Concentrations and annual fluxes for selected water-quality constituents from the USGS National Stream Quality Accounting Network (NASQAN) 1996-2000

This report contains concentrations and annual mass fluxes (loadings) for a broad range of water-quality constituents measured during 1996-2000 as part of the U.S. Geological Survey National Stream Quality Accounting Network (NASQAN). During this period, NASQAN operated a network of 40-42 stations in four of the largest river basins of the USA: the Colorado, the Columbia, the Mississippi (including the Missouri and Ohio), and the Rio Grande. The report contains surface-water quality data, streamflow data, field measurements (e.g. water temperature and pH), sediment-chemistry data, and quality-assurance data; interpretive products include annual and average loads, regression parameters for models used to estimate loads, sub-basin yield maps, maps depicting percent detections for censored constituents, and diagrams depicting flow-weighted average concentrations. Where possible, a regression model relating concentration to discharge and season was used for flux estimation. The interpretive context provided by annual loads includes identifying source and sink areas for constituents and estimating the loadings to receiving waters, such as reservoirs or the ocean.

Water-Resources Investigations Report↗

Assessment of the Joplin 1° x 2° quadrangle, Kansas and Missouri, for Mississippi Valley-type deposits and other minerals

This map is a part of the folio of maps of the Joplin 1° X 2° quadrangle, Kansas and Missouri, which was prepared under the Conterminuous United States Mineral Assessment Program. Other publications in this folio to date include the U.S. Geological Survey Miscellaneous Field Studies Maps MF-2125-A through D (Erickson and others, 1990; Grisafe and Rueff, 1992; Blair and others, 1992; McCafferty and Cordell, 1992). Additional maps showing other geologic aspects of the Joplin quadrangle will be published as U.S. Geological Survey maps bearing this same serial number with different letter suffixes (MF-2125-F, -G, and so on).

Kansas, Missouri↗

Characterizing the diverse hydrogeology underlying rivers and estuaries using new floating transient electromagnetic methodology

The hydrogeology below large surface water features such as rivers and estuaries is universally under-informed at the long reach to basin scales (tens of km+). This challenge inhibits the accurate modeling of fresh/saline groundwater interfaces and groundwater/surface water exchange patterns at management-relevant spatial extents. Here we introduce a towed, floating transient electromagnetic (TEM) system (i.e. FloaTEM) for rapid (up to 15 km/h) high resolution electrical mapping of the subsurface below large water bodies to depths often a factor of 10 greater than other towed instruments. The novel FloaTEM system is demonstrated at a range of diverse 4th through 6th-order riverine settings across the United States including 1) the Farmington River, near Hartford, Connecticut; 2) the Upper Delaware River near Barryville, New York; 3) the Tallahatchie River near Shellmound, Mississippi; and, 4) the Eel River estuary, on Cape Cod, near Falmouth, Massachusetts. Airborne frequency-domain electromagnetic and land-based towed TEM data are also compared at the Tallahatchie River site, and streambed geologic scenarios are explored with forward modeling. A range of geologic structures and pore water salinity interfaces were identified. Process-based interpretation of the case study data indicated FloaTEM can resolve varied sediment-water interface materials, such as the accumulation of fines at the bottom of a reservoir and permeable sand/gravel riverbed sediments that focus groundwater discharge. Bedrock layers were mapped at several sites, and aquifer confining units were defined at comparable resolution to airborne methods. Terrestrial fresh groundwater discharge with flowpaths extending hundreds of meters from shore was also imaged below the Eel River estuary, improving on previous hydrogeological characterizations of that nutrient-rich coastal exchange zone. In summary, the novel FloaTEM system fills a critical gap in our ability to characterize the hydrogeology below surface water features and will support more accurate prediction of groundwater/surface water exchange dynamics and fresh-saline groundwater interfaces.

Science of the Total Environment↗

Nutrient mass balance and trends, Mobile River Basin, Alabama, Georgia, and Mississippi

A nutrient mass balance - accounting for nutrient inputs from atmospheric deposition, fertilizer, crop nitrogen fixation, and point source effluents; and nutrient outputs, including crop harvest and storage - was calculated for 18 subbasins in the Mobile River Basin, and trends (1970 to 1997) were evaluated as part of the U.S. Geological Survey National Water Quality Assessment (NAWQA) Program. Agricultural nonpoint nitrogen and phosphorus sources and urban nonpoint nitrogen sources are the most important factors associated with nutrients in this system. More than 30 percent of nitrogen yield in two basins and phosphorus yield in eight basins can be attributed to urban point source nutrient inputs. The total nitrogen yield (1.3 tons per square mile per year) for the Tombigbee River, which drains a greater percentage of agricultural (row crop) land use, was larger than the total nitrogen yield (0.99 tons per square mile per year) for the Alabama River. Decreasing trends of total nitrogen concentrations in the Tombigbee and Alabama Rivers indicate that a reduction occurred from 1975 to 1997 in the nitrogen contributions to Mobile Bay from the Mobile River. Nitrogen concentrations also decreased (1980 to 1995) in the Black Warrior River, one of the major tributaries to the Tombigbee River. Total phosphorus concentrations increased from 1970 to 1996 at three urban influenced sites on the Etowah River in Georgia. Multiple regression analysis indicates a distinct association between water quality in the streams of the Mobile River drainage basin and agricultural activities in the basin.

Alabama, Georgia, Mississippi↗

The Missouri groundwater-level observation network

The Missouri groundwater-level observation well network is a series of wells across the State of Missouri in which groundwater levels are monitored in real time and periodically. The wells monitor the water levels in multiple key aquifers, such as the Ozark aquifer in the Salem and Springfield Plateaus and the Mississippi Alluvial Plain aquifer in the South-eastern Lowlands. As of 2018, 150 real-time sites are operated as a cooperative effort between the Missouri Department of Natural Resources (MoDNR) and the U.S. Geological Survey. This fact sheet describes the network and well data from the network.

Missouri↗