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At least 343 records · Page 19Linked to original sources
USGS1994

Water resources data, Mississippi, water year 1993

Water resources data for the 1993 water year for Mississippi consist of records of surface water, ground water, and precipitation in the State. Specifically, it contains:(1) Discharge records for 83 streamflow-gaging stations, stage records for 19 of these gaging stations, discharge records for 107 partial-record or miscellaneous streamflow stations, including 7 flood hydrograph partial-record stations, 55 crest-stage partial-record stations and 46 special study and miscellaneous sites, (2) stage only at 6 gaging stations,(3) water-quality records for 24 streamflow-gaging stations, 2 ungaged streamsites 6 partial-record or miscellaneous sites, 21 short-term study sites, 384 wells, and 3 precipitation-quality stations, and (4) water-level records for 231 observation wells. Records obtained from water-resources investigations are also included in special sections of the report. These data represent that part of the National Water Data System operated by the U.S. Geological Survey, and cooperating local, State, and Federal agencies in Mississippi.

Mississippi↗
USGS2007

Sedimentation History of Halfway Creek Marsh, Upper Mississippi River National Wildlife and Fish Refuge, Wisconsin, 1846-2006

The history of overbank sedimentation in the vicinity of Halfway Creek Marsh near La Crosse, Wis., was examined during 2005?06 by the U.S. Geological Survey and University of Wisconsin?Madison as part of a broader study of sediment and nutrient loadings to the Upper Mississippi River bottomlands by the U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and U.S. Geological Survey. Historical sedimentation patterns and rates were interpreted from field-scale topographic surveys and sediment cores collected from the marsh and upstream flood plains. Historical maps and aerial photographs were used to establish the timing of disturbances and to document changes in channel patterns after Euro-American settlement (post 1846). Episodic overbank sedimentation patterns and rates were linked to watershed agricultural activity, large floods, artificial levee construction, channel alterations, and dam failures over the past 160 years. These forces affected sedimentation on and between levees, the development of alluvial fans and flood-plain splays, and the general pattern of flood-plain sedimentation through the upper and lower marsh. Historical overbank deposits, episodically deposited after about 1860, are as much as 6 feet thick in the upper marsh and as much as 4 feet thick in the lower marsh, representing a total volume of approximately 1.8 million cubic yards. These stratified deposits consist of multiple layers of silt and clay, very fine to fine sand, and some medium to very coarse sand. Coarse-grained deposits are associated with flood-plain splays caused by breaches in artificial levees during large floods. Estimated sedimentation rates were highest from 1919 to 1936 [26,890 cubic yards per year (yd3/yr)] and exceeded by about 30 times the 1846?85 rate of 920 yd3/yr and exceeded by 7 times the 1994?2006 rate of 3,740 yd3/yr. The 1994?2006 sedimentation rate was the lowest since Euro-American settlement, but natural levees along the 1994?2006 channel of Halfway Creek through the lower marsh continued to form and are currently (2006) about 1 foot higher than the surrounding marsh. Natural levee building in the lower marsh from 1994?2006 was accentuated by the lack of overbank sediment storage in the upper marsh. The historical storage of sediment in the upper and lower marsh affects modern streamflow and sediment transport processes of Halfway Creek and Sand Lake Coulee through the marsh, and it also affects marsh vegetation and wildlife habitat. Results from this investigation will help improve the understanding of how past overbank sedimentation patterns continue to influence modern and future water quality, sediment transport, nutrient loads, and water-related resources in riparian habitats common to the Upper Mississippi River National Wildlife and Fish Refuge.

Scientific Investigations Report↗
USGS2009

The Mississippi Embayment Regional Aquifer Study (MERAS): Documentation of a groundwater-flow model constructed to assess water availability in the Mississippi embayment

The Mississippi Embayment Regional Aquifer Study (MERAS) was conducted with support from the Groundwater Resources Program of the U.S. Geological Survey Office of Groundwater. This report documents the construction and calibration of a finite-difference groundwater model for use as a tool to quantify groundwater availability within the Mississippi embayment. To approximate the differential equation, the MERAS model was constructed with the U.S. Geological Survey's modular three-dimensional finite-difference code, MODFLOW-2005; the preconditioned conjugate gradient solver within MODFLOW-2005 was used for the numerical solution technique. The model area boundary is approximately 78,000 square miles and includes eight States with approximately 6,900 miles of simulated streams, 70,000 well locations, and 10 primary hydrogeologic units. The finite-difference grid consists of 414 rows, 397 columns, and 13 layers. Each model cell is 1 square mile with varying thickness by cell and by layer. The simulation period extends from January 1, 1870, to April 1, 2007, for a total of 137 years and 69 stress periods. The first stress period is simulated as steady state to represent predevelopment conditions. Areal recharge is applied throughout the MERAS model area using the MODFLOW-2005 Recharge Package. Irrigation, municipal, and industrial wells are simulated using the Multi-Node Well Package. There are 43 streams simulated by the MERAS model. Each stream or river in the model area was simulated using the Streamflow-Routing Package. The perimeter of the model area and the base of the flow system are represented as no-flow boundaries. The downgradient limit of each model layer is a no-flow boundary, which approximates the extent of water with less than 10,000 milligrams per liter of dissolved solids. The MERAS model was calibrated by making manual changes to parameter values and examining residuals for hydraulic heads and streamflow. Additional calibration was achieved through alternate use of UCODE-2005 and PEST. Simulated heads were compared to 55,786 hydraulic-head measurements from 3,245 wells in the MERAS model area. Values of root mean square error between simulated and observed hydraulic heads of all observations ranged from 8.33 feet in 1919 to 47.65 feet in 1951, though only six root mean square error values are greater than 40 feet for the entire simulation period. Simulated streamflow generally is lower than measured streamflow for streams with streamflow less than 1,000 cubic feet per second, and greater than measured streamflow for streams with streamflow more than 1,000 cubic feet per second. Simulated streamflow is underpredicted for 18 observations and overpredicted for 10 observations in the model. These differences in streamflow illustrate the large uncertainty in model inputs such as predevelopment recharge, overland flow, pumpage (from stream and aquifer), precipitation, and observation weights. The groundwater-flow budget indicates changes in flow into (inflows) and out of (outflows) the model area during the pregroundwater-irrigation period (pre-1870) to 2007. Total flow (sum of inflows or outflows) through the model ranged from about 600 million gallons per day prior to development to 18,197 million gallons per day near the end of the simulation. The pumpage from wells represents the largest outflow components with a net rate of 18,197 million gallons per day near the end of the model simulation in 2006. Groundwater outflows are offset primarily by inflow from aquifer storage and recharge.

Alabama, Arkansas, Kentucky, Louisiana, Mississipp↗
USGS2006

Annual dissolved nitrite plus nitrate and total phosphorous loads for the Susquehanna, St. Lawrence, Mississippi-Atchafalaya, and Columbia River basins, 1968-2004

Annual stream-water loads were calculated near the outlet of four of the larger river basins (Susquehanna, St. Lawrence, Mississippi-Atchafalaya, and Columbia) in the United States for dissolved nitrite plus nitrate (NO2 + NO3) and total phosphorus using LOADEST load estimation software. Loads were estimated for the period 1968-2004; although loads estimated for individual river basins and chemical constituent combinations typically were for shorter time periods due to limitations in data availability. Stream discharge and water-quality data for load estimates were obtained from the U.S. Geological Survey (USGS) with additional stream discharge data for the Mississippi-Atchafalaya River Basin from the U.S. Army Corps of Engineers. The loads were estimated to support national assessments of changes in stream nutrient loads that are periodically conducted by Federal agencies (for example, U.S. Environmental Protection Agency) and other water- and land-resource organizations. Data, methods, and results of load estimates are summarized herein; including World Wide Web links to electronic ASCII text files containing the raw data. The load estimates are compared to dissolved NO2 + NO3 loads for three of the large river basins from 1971 to 1998 that the USGS provided during 2001 to The H. John Heinz III Center for Science, Economics and the Environment (The Heinz Center) for a report The Heinz Center published during 2002. Differences in the load estimates are the result of using the most up-to-date monitoring data since the 2001 analysis, differences in how concentrations less than the reporting limit were handled by the load estimation models, and some errors and exclusions in the 2001 analysis datasets (which resulted in some inaccurate load estimates).

Open-File Report↗
USGS2025

Temporal changes in nutrient concentrations in the Lower Grand River and selected drainage basins, Missouri and Iowa, during the Mississippi River Basin Healthy Watersheds Initiative (2010–23)

This report describes a cooperative study by the U.S. Geological Survey and Missouri Department of Natural Resources that evaluated temporal changes in total nitrogen (TN) and total phosphorus (TP) concentrations in the Lower Grand River hydrologic unit. The study focused on trends since 2010, when the basin was designated as a priority drainage basin of the Mississippi River Basin Healthy Watersheds Initiative (MRBI). At three local drainage basins within the Lower Grand hydrological unit (MRBI sites), stream nutrient trends were evaluated using flow-adjusted (FA) TN and TP concentrations for water years 2011 through 2023. FATN concentration trends were not statistically significant for any MRBI site. One site (site 2) showed a statistically significant increasing trend in FATP concentration, indicating a possible increase in phosphorus sources in parts of the basin. Overall, streamflow variability appeared to be the dominant factor affecting nutrient concentrations at MRBI sites. At five regional drainage basins, including the Grand River and nearby rivers with data from 1994 through 2023 (long-term sites), annual flow-normalized (FN) TN and TP concentrations were evaluated for trends before (water years 2000–10) and during (water years 2010–23) the MRBI. For water years 2010 through 2023, annual FNTN and FNTP concentrations decreased in the Grand River, as well as in the Nodaway and Chariton Rivers, which were not targeted by the MRBI. The Grand River (site 9) reversed from increasing to decreasing FNTP concentrations after 2010, with a 26-percent reduction. Annual FNTN and FNTP concentrations also decreased at the Missouri River sites. While nutrient reductions in the Grand River may reflect the effects of implemented conservation practices, similar trends in nearby, nontargeted rivers and the absence of strong decreasing trends at MRBI sites suggest that broader regional factors, instead of or in addition to MRBI efforts, may have contributed to nutrient reductions in the Grand River.

Iowa, Missouri↗
USGS2013

Geologic controls on regional and local erosion rates of three northern Gulf of Mexico barrier-island systems

The stratigraphy of sections of three barrier island systems in the northeastern Gulf of Mexico (Apalachicola, Mississippi, and Chandeleur) have been mapped using geophysical and coring techniques to assess the influence of geologic variations in barrier lithosomes and adjoining inner shelf deposits on long-term rates of shoreline change at regional and local scales. Regional scale was addressed by comparing average geologic characteristics of the three areas with mean shoreline-change rates for each area. Regionally, differences in sand volume contained within the part of the barrier lithosome above sea level, sand volume on the inner shelf, and to a lesser extent, sediment grain size correlate with shoreline change rates. Larger sand volumes and coarser grain sizes are found where erosion rates are lower. Local scale was addressed by comparing alongshore variations in barrier island and inner shelf geology with alongshore variations in shoreline change. Locally, long-term shoreline change rates are highest directly shoreward of paleovalleys exposed on the inner shelf. While geology is not the sole explanation for observed differences in shoreline change along these three coastal regions, it is a significant contributor to change variability.

Journal of Coastal Research↗
USGS2021

Machine-learning predictions of redox conditions in groundwater in the Mississippi River Valley alluvial and Claiborne aquifers, south-central United States

Machine-learning models developed by the U.S. Geological Survey were used to predict iron concentrations and the probability of dissolved oxygen (DO) concentrations exceeding a threshold of 1 milligram per liter (mg/L) in groundwater in aquifers of the Mississippi embayment physiographic region. DO and iron concentrations are driven by and reflect the oxidation-reduction (redox) conditions in groundwater. Predictions from boosted regression trees, a type of machine-learning model, of iron concentration and DO threshold probability were used to categorize redox zones in the Mississippi River Valley alluvial aquifer (MRVA), middle Claiborne aquifer (MCAQ), and lower Claiborne aquifer (LCAQ). Model predictions indicated that DO concentrations greater than 1 mg/L are uncommon across the MRVA. DO events (where the predicted probability was greater than 0.5) tended to occur on the margins of the MRVA and in upland areas where MCAQ and LCAQ units crop out at the surface or are at shallow depth. Predicted iron concentrations were higher in the MRVA than in the MCAQ and LCAQ. Uncer­tainty in predicted iron concentrations tended to be high in areas where measured concentrations were also high, result­ing in small areas (encompassing less than 1.5 percent of the areal extent of the MRVA) of predicted iron concentrations that exceeded 100,000 micrograms per liter. Despite the large magnitude of overpredicted iron concentrations, the general proportion and spatial distribution of predicted iron concen­trations reflected observed concentrations in groundwater wells. Where the probability of exceeding a DO concentration of 1 mg/L was 0.8 or more and the iron concentration was less than 1,000 micrograms per liter, aquifers were catego­rized as oxic. Oxic conditions were mostly in the uplands where MCAQ and LCAQ units crop out at the margins of the modeled area. The MRVA was mostly anoxic, which was controlled by DO threshold probabilities less than 0.1. The predictions and redox zones support conceptual models of redox conditions in the Mississippi embayment. The MRVA is predominantly anoxic with high iron concentrations. In the Claiborne aquifers (including the MCAQ and LCAQ), groundwater flows along regional flow paths toward the axis of the Mississippi embayment (the approximate location of the Mississippi River), the residence time in the aquifer increases, DO is consumed, and iron concentrations generally increase. Elevated concentrations of trace elements, such as manganese and arsenic, are often associated with reducing conditions in anoxic and mixed anoxic zones, but other factors such as sediment mineralogy affect the occurrence and distribution of these constituents.

Alabama, Arkansas, Kentucky, Louisiana, Mississipp↗
USGS2021

Continuous monitoring and Bayesian estimation of nutrient and sediment loads from Illinois watersheds, for water years 2016–2020

The State of Illinois is one of the leading contributors of nitrogen, phosphorus, and suspended sediment to the Mississippi River and the Gulf of Mexico. During water years 2016–20, the U.S. Geological Survey, in cooperation with the Illinois Environmental Protection Agency, operated continuous monitoring stations on eight major rivers in Illinois to better quantify nutrient and sediment loadings from the State of Illinois to the Mississippi River. This report estimates nitrate, phosphorus, and suspended-sediment loadings over that period, which can provide a benchmark against which to assess future changes in loading. In addition, this report develops a new method for incorporating the uncertainty created by gaps in continuous datasets based on Bayesian machine learning. Data gaps are a common problem in continuous monitoring, and gap filling is necessary to quantify loadings and the uncertainty in loadings, which is essential if these results are to provide a benchmark for future studies. The uncertainty estimates may also be useful in an operational context, and this report provides examples of how uncertainty can be used in monitoring-network design and potentially reducing monitoring costs.

Illinois↗
USGS2017

The Upper Mississippi River System—Topobathy

The Upper Mississippi River System (UMRS), the navigable part of the Upper Mississippi and Illinois Rivers, is a diverse ecosystem that contains river channels, tributaries, shallow-water wetlands, backwater lakes, and flood-plain forests. Approximately 10,000 years of geologic and hydrographic history exist within the UMRS. Because it maintains crucial wildlife and fish habitats, the dynamic ecosystems of the Upper Mississippi River Basin and its tributaries are contingent on the adjacent flood plains and water-level fluctuations of the Mississippi River. Separate data for flood-plain elevation (lidar) and riverbed elevation (bathymetry) were collected on the UMRS by the U.S. Army Corps of Engineers’ (USACE) Upper Mississippi River Restoration (UMRR) Program. Using the two elevation datasets, the U.S. Geological Survey (USGS) Upper Midwest Environmental Sciences Center (UMESC) developed a systemic topobathy dataset.

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗
USGS2001

Nutrient and suspended-sediment concentrations and loads and benthic-invertebrate data for tributaries to the St. Croix River, Wisconsin and Minnesota, 1997-99

Nutrient and suspended-sediment data were collected on major tributaries to the St. Croix River during 1997-99 as part of three studies. The first study, done in 1997 as part of the U.S. Geological Survey?s National Water-Quality Assessment Program Upper Mississippi Study Unit, was a widespread synoptic survey of nutrient and suspended-sediment concentrations, loads, and yields during snowmelt. Runoff from snowmelt in agricultural areas and other areas with low permeability soils had significantly greater nutrient concentrations than forested areas, whereas differences in suspended-sediment loading were not detected. In 1998, synoptic samplings of 11 tributaries were done during snowmelt, base-flow, and storm-runoff periods. These studies showed that the Apple, Willow, and Kinnickinnic Rivers were major contributors of suspended sediments and nutrients to the St. Croix River during base flow and storm-runoff events. Nitrate concentrations were high during base flow in the agricultural tributaries?specifically, the Kinnickinnic (4.83 mg/L), Willow (1.53 mg/L), and Apple (0.79 mg/L) Rivers?possibly from ground-water recharge or point-source contributions. Extensive water-quality sampling was done monthly and during high-flow events in water year 1999 (October 1, 1998 to September 30, 1999) in coordination with continuous streamflow monitoring at 12 sites in the St. Croix River Basin. These data were used to compute annual nutrient and suspended-sediment loads and yields at the monitored sites for water year 1999. Relations among environmental characteristics and calculated annual nutrient and suspended-sediment yields were used to estimate loading from unmonitored parts of the basin. The environmental characteristics found to best estimate annual yields were soil characteristics (clay, permeability of soil, and erodibility), basin slope and area, and the percentages of wetland and urban areas in the basins. Variability in 1999 rainfall intensity resulted in annual yields from several northern, forested basins being higher than those from the southern, agricultural basins. The Sunrise River had the highest annual suspended-sediment and nutrient yields in the basin in 1999. Concentrations and instantaneous loading rates varied as much among various flow conditions at individual sites as among sites during the three years of study. Benthic invertebrates were sampled and indices of water quality were calculated at 16 tributaries in fall 1999. Benthic invertebrate indices indicated excellent to good water quality at all tributaries except Valley Creek, Willow River, and Kettle River. No relations were found between benthic invertebrate indices and the calculated and estimated 1999 annual tributary loads and yields.

Minnesota, Wisconsin↗
USGS2001

Hydrogeology and ground-water flow in the Memphis and Fort Pillow aquifers in the Memphis area, Tennessee

On the basis of known hydrogeology of the Memphis and Fort Pillow aquifers in the Memphis area, a three-layer, finite-difference numerical model was constructed and calibrated as the primary tool to refine understanding of flow in the aquifers. The model was calibrated and tested for accuracy in simulating measured heads for nine periods of transient flow from 1886-1985. Testing and sensitivity analyses indicated that the model accurately simulated observed heads areally as well as through time. The study indicates that the flow system is currently dominated by the distribution of pumping in relation to the distribution of areally variable confining units. Current withdrawal of about 200 million gallons per day has altered the prepumping flow paths, and effectively captured most of the water flowing through the aquifers. Ground-water flow is controlled by the altitude and location of sources of recharge and discharge, and by the hydraulic characteristics of the hydrogeologic units. Leakage between the Fort Pillow aquifer and Memphis aquifer, and between the Memphis aquifer and the water-table aquifers (alluvium and fluvial deposits) is a major component of the hydrologic budget. The study indicates that more than 50 percent of the water withdrawn from the Memphis aquifer in 1980 is derived from vertical leakage across confining units, and the leakage from the shallow aquifer (potential source of contamination) is not uniformly distributed. Simulated leakage was concentrated along the upper reaches of the Wolf and Loosahatchie Rivers, along the upper reaches of Nonconnah Creek, and the surficial aquifer of the Mississippi River alluvial plain. These simulations are supported by the geologic and geophysical evidence suggesting relatively thin or sandy confining units in these general locations. Because water from surficial aquifers is inferior in quality and more susceptible to contamination than water in the deeper aquifers, high rates of leakage to the Memphis aquifer may be cause for concern. A significant component of flow (12 percent) discharging from the Fort Pillow aquifer was calculated as upward leakage to the Memphis aquifer. This upward leakage was generally limited to areas near major pumping centers in the Memphis aquifer, where heads in the Memphis aquifer have been drawn significantly below heads in the Fort Pillow aquifer. Although the Fort Pillow aquifer is not capable of producing as much water as the Memphis aquifer for similar conditions, it is nonetheless a valuable resource throughout the area.

Water-Resources Investigations Report↗