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At least 163 records · Page 9Linked to original sources

Water-quality assessment of part of the upper Mississippi River Basin, Minnesota and Wisconsin— Ground-water quality in the Prairie du Chien-Jordan aquifer, 1996

The Prairie du Chien-Jordan (PDCJ) aquifer (Prairie du Chien-Trempealeau aquifer in Wisconsin), composed of dolomite and sandstone of Cambrian to Ordovician age, is the principal bedrock aquifer in the Upper Mississippi River study unit of the National Water-Quality Assessment (NAWQA) Program. The aquifer supplies approximately 75 percent of the ground water withdrawn in the area. In certain areas, the aquifer is overlain by bedrock or glacial deposits having low hydraulic conductivity (termed "confined portion" of the aquifer in this report). In other areas the aquifer is overlain by glacial sand and gravel deposits having greater hydraulic conductivity (termed "unconfined portion" of the aquifer in this report). Differences in the hydrogeologic characteristics of these overlying units have potential to affect the downward movement of water and of contaminants into the aquifer from the land surface. Ground-water samples were collected from 50 domestic wells completed in this aquifer in July, August, and September of 1996 as part of the U.S. Geological Survey's National WaterQuality Assessment Program. The purpose of this report is to describe the chemical characteristics of water in the PDCJ aquifer and to summarize the differences in water quality in confined and unconfined portions of the aquifer. Twenty-five wells were sampled in each portion of the aquifer. Water samples from the wells were measured for physical parameters and analyzed for concentrations of major ions, nutrients, dissolved organic carbon, trace metals, radon, tritium, pesticides, and volatile organic compounds. Differences in anthropogenic and naturally occurring materials in water between confined and unconfined portions of the PDCJ aquifer are small and frequently the differences are not statistically significant at the 95 percent confidence level. Dissolved oxygen concentrations were slightly less and specific conductances and alkalinities were slightly greater in water in the confined portion of the aquifer. Only the differences in specific conductance and alkalinity, however, were statistically significant at the 95 percent confidence level (two sample t-test). Concentrations of most major ions were generally greater in water from the confined portion of the aquifer. Nitrate (nitrite plus nitrate as N) and phosphorus were generally greater in the unconfined portion of the PDCJ aquifer although the differences were not statistically significant at the 95 percent confidence level (nonparametric Mann-Whitney test). In the confined portion of the aquifer no samples exceeded the maximum contaminant level of 10 milligrams per liter for nitrate. In the unconfined portion of the aquifer nitrate in two samples exceeded the maximum contaminant level of 10 milligrams per liter. Phosphorus concentrations were generally about an order of magnitude less than nitrate concentrations. Iron and manganese concentrations commonly exceeded the secondary maximum contaminant levels set by the U.S. Environmental Protection Agency and were generally greater in the confined portion of the PDCJ aquifer, although the differences were not statistically significant at the 95 percent confidence level (nonparametric Mann-Whitney test). Radon concentrations were greater in the confined portion of the aquifer than in the unconfined portion, although the difference was not statistically significant at the 95 percent confidence level (two sample t-test), with medians of 500 and 340 picoCuries per liter, respectively. Sixty-six percent of the radon concentrations were greater than the suspended maximum contaminant level of 300 picoCuries per liter. Tritium concentrations indicate that water in the unconfined portion of the PDCJ aquifer may have been recharged more recently than water in the confined portion of the aquifer, although differences in tritium concentrations between confined and unconfined portions of the aquifer were not statistically significant at the 95 percent confidence level (nonparametric MannWhitney test). Atrazine and its metabolite, deethylatrazine, were the most frequently detected pesticide compounds in water samples from the PDCJ aquifer. Volatile organic compounds were detected in 41 of the 50 water samples, but none of the concentrations exceeded 1 microgram per liter. Concentrations of volatile organic compounds were slightly greater in the unconfined portion, although the differences in detection rates were not statistically significant at the 95 percent confidence level (nonparametric Mann-Whitney test). Carbon disulfide and methyl chloride were the most frequently detected volatile organic compounds. Water in the unconfined portion of the PDCJ aquifer in Minnesota and Wisconsin appears to be affected to a greater degree by anthropogenic activities than water in the confined portion of the aquifer. Water in the confined portion has a longer residence time and greater concentrations of dissolution products of minerals. In general, however, differences in anthropogenic and naturally occurring materials among confined and unconfined portions of the aquifer are small and frequently not significantly different.

Minnesota, Wisconsin↗

A field guide to amphibian larvae and eggs of Minnesota, Wisconsin, and Iowa

Apparent worldwide declines in amphibian populations (Pechmann and Wake 1997) have stimulated interest in amphibians as bioindicators of the health of ecosystems. Because we have little information on the population status of many species, there is interest by public and private land management agencies in monitoring amphibian populations. Amphibian egg and larval surveys are established methods of surveying pond-breeding amphibians. Adults may be widely dispersed across the landscape, but eggs and larvae are confined to the breeding site during a specific season of the year. Also, observations of late-stage larvae or metamorphs are evidence of successful reproduction, which is an important indicator of the viability of the population. The goal of this guide is to help students, natural resources personnel, and biologists identify eggs and larval stages of amphibians in the field without the aid of a microscope.

Iowa, Minnesota, Wisconsin↗

Water-table map of Walworth County, Wisconsin

A map of the water table in Walworth County in southeastern Wisconsin was prepared using water levels from nearly 600 wells. The work was done as a cooperative project between the U.S. Geological Survey, the University of Wisconsin-Extension, Geological and Natural History Survey, and the Southeastern Wisconsin Regional Planning Commission. The map (scale 1:100 ,000) shows the altitude of the water table in increments of 20 feet, with supplemental 10-foot contours. The altitude ranges from less than 780 feet along parts of the eastern border of the county to more than 1,000 feet in a small area near the central part of the county. (Woodard-USGS)

Wisconsin↗

Development of an assessment tool for agricultural best management practice implementation in the Great Lakes Restoration Initiative priority watersheds—Upper East River, tributary to Green Bay, Wisconsin

Introduction The Great Lakes face a number of serious challenges that cause damage to water quality, habitat, ecology, and coastal health. Excess nutrients from point and nonpoint sources have a history of causing harmful algal blooms (HABs); since the late 1990s, a resurgence of HABs have forced beach closures and resulted in water quality impairments across the Great Lakes. Studies increasingly point to phosphorus (P) runoff from agricultural lands as the cause of these HABs. In 2010, the Great Lakes Restoration Initiative (GLRI) was launched to revitalize the Great Lakes. The GLRI aims to address the challenges facing the Great Lakes and provide a framework for restoration and protection. As part of this effort, the Priority Watersheds Work Group (PWWG), cochaired by the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Agriculture-Natural Resources Conservation Service (USDA–NRCS), is targeting Priority Watersheds (PWs) to reduce the amount of P reaching the Great Lakes. Within the PWs, USDA–NRCS identifies small-scale subbasins with high concentrations of agriculture for coordinated nutrient reduction efforts and enhanced monitoring and modeling. The USDA–NRCS supplies financial and/or technical assistance to producers to install or implement best management practices (BMPs) to lessen the negative effects of agriculture to water quality; additional funding is provided by the GLRI through USDA–NRCS to saturate the small-scale subbasins with BMPs. The watershed modeling component, introduced in this fact sheet, assesses the effectiveness of USDA–NRCS funded BMPs, and nutrient reductions because of GLRI or other funding programs are differentiated. Modeling scenarios consider BMPs that have already been applied and those planned to be implemented across the small-scale subbasins.

Wisconsin↗

Water-quality and aquatic-community characteristics of selected reaches of the St. Croix River, Minnesota and Wisconsin, 2000

Synoptic sampling was used to determine chemical and biological characteristics of the St. Croix River within a study reach that extended from near Danbury, Wisconsin to the confluence with the Mississippi River at Prescott, Wisconsin. The study was conducted August 7- September 25, 2000 during summer low flow. Dissolved-residue concentrations were found to increase gradually as the river flows downstream, with an abrupt increase downstream of the confluence with the Sunrise River that was primarily attributed to an increase in calcium and magnesium. Dissolved residue concentrations were further augmented by increased yields of chloride and sulfate in the part of the St. Croix Basin between Nevers Dam near St. Croix Falls, Wisconsin and Marine on St. Croix, Minnesota. Nearly all of the nitrogen in transport was in the form of nitrate and organic nitrogen. Organic nitrogen, mainly in particulate form, accounted for most of the gain in total nitrogen load within the study reach. Nitrogen loading to the mainstem indicated relatively uniform nitrogen inputs from the Clam River, Kettle River, and Snake River watersheds. The rate of nitrogen load accrual increased downstream of the confluence with the Sunrise River and in the subreach extending from Nevers Dam through St. Croix Falls to Franconia, Minnesota. Nitrogen load also increased, primarily because of nitrate input, in the part of Lake St. Croix downstream of the confluence with the Kinnickinnic River. Total phosphorus concentrations and loads reflected variations in the amount of particulate phosphorus in transport. Phosphorus loading increased in the part of the St. Croix River that includes Danbury and the confluences of the Yellow River and Clam River. Phosphorus loading also increased downstream of the confluence with the Sunrise River, but the greatest load increase occurred between Nevers Dam and Franconia. Phosphorus load decreased substantially as the river flowed through the pooled reach of Lake St. Croix downstream of Stillwater. Suspended-sediment concentrations were low, ranging from 4.0 to 36 milligrams per liter. The small amount of sediment in transport was reflected in turbidity measurements that ranged from 0.5 to 3.6 Nephelometry Turbidity Units, and transparency tube measurements that were greater than 60 centimeters at all sites. Biological measures of resource quality change in the St. Croix River along its course from Danbury to Prescott. Changes in the biological indicators of resource quality (fish and invertebrate community composition) are most notable just upstream and downstream of the dam at St. Croix Falls, Wisconsin. Aquatic communities in the upper St. Croix River, from near Danbury to near Rush City, Minnesota, indicate minimal physical and chemical disturbance as evidenced by relatively high taxa richness and greater proportions of taxa intolerant to physical and chemical disturbance. In contrast, aquatic communities downstream of the Sunrise River to Marine on St. Croix indicate both physical and chemical disturbance. Resource monitoring, consisting of short-term diagnostic studies, may be needed in parts of the St. Croix River mainstem and tributaries where results from this study indicate constituent loading is greatest and where the aquatic community composition indicates disturbance. Longer-term trend monitoring may be needed to detect physical, chemical and biological responses to natural processes and human activities in the St. Croix River Basin.

Minnesota, Wisconsin↗

Hydrology of the Little Plover River basin, Portage County, Wisconsin, and the effects of water resource development

The Little Plover River basin is in the sand-plain area of central Wisconsin. The basin and the surrounding sand-plain area provide a good fish and wildlife habitat and is a popular locale for sport fishing. Good yields may be obtained in the area from irrigated crops, and the irrigated acreage has been increasing rapidly in recent years. Sportsmen and conservationists are concerned about the effects of increased development of the water resources on the streams as trout habitat. In the past, many political and legal conflicts among water users have arisen from erroneous opinions as to the behavior of water. Many of these conflicts would be diminished or eliminated if the participants were cognizant of fundamental hydrologic principles. This study was made to demonstrate the extent and nature of the interrelation of ground water and surface water and the fundamental hydrologic principles governing water movement. The study was also made to determine the hydrologic changes that might occur following development, to provide information that might be used as a basis for planning water development, and for drafting legislation that recognizes the relation between ground water and surface water. Water has been developed in the Little Plover River basin for industry, for domestic and stock supplies, and for irrigation. Irrigated acreage is increasing in the area, and the use of water for irrigation may alter the hydrology of the basin somewhat. About 4,000-4,500 acres of land within the basin, or 50-60 percent of the basin area, is suitable for irrigated farming, but probably no more than 2,500 acres will be under irrigation in any one year, unless present crop-rotation practices are changed. Most of the Little Plover River basin is underlain by from 40 to 100 feet of glacial outwash consisting of highly permeable sand and gravel. The glacial outwash is the main aquifer in the area and is capable of yielding large quantities of water to wells. An aquifer test in the area indicated that the coefficient of transmissibility of the glacial outwash is about 140,000 gallons per day per foot. The specific yield of the outwash is about 20 percent, as determined from water-level and streamfiow data. Morainal deposits occur locally with the glacial outwash. These deposits transmit water readily and do not form barriers to ground water in the outwash. Relatively impermeable crystalline rocks underlie the glacial deposits, and a sandstone ridge of low permeability impedes the movement of ground water from the basin by underflow. The glacial outwash and morainal deposits are recharged by infiltration of 9-10 inches of the 31 inches of precipitation that falls on the area in an average year. If it is not withdrawn by wells for consumptive use or by phreatophytes, water that infiltrates the sand and gravel discharges later into the Little Plover River. This ground-water discharge constitutes 90-95 percent of the total flow of the Little Plover River. Annual evapotranspiration varies considerably, but generally ranges from 2 to 8 inches less than the potential evapotranspiration of 24 inches. Consumptive use of irrigation water averages about 4 inches per year. Most of the water pumped from wells otherwise would be discharged to the stream, and consumptive use of irrigation water will deplete streamflow by the amount of evapotranspiration. Pumping wells have little effect on the water level in the highly permeable sand and gravel. Significant interference between wells would occur only if large capacity wells were within a few tens of feet of each other. Ground water and surface water are closely interrelated in the sand-plain area and ground-water withdrawals near the Little Plover River may cause a measurable streamflow depletion. In a test, a well that was pumping about 1,120 gpm (gallons per minute) and that was 300 feet from the stream derived about 30 percent of its flow from the stream after 3 days of pumping. For this study, the effects of increased ground-water development were evaluated from a hypothetical development schedule, for which it was assumed that 500 acres were irrigated the first year and that an additional 50 acres were irrigated in each succeeding year for 10 years. It also was assumed that the average annual consumptive-use requirement for irrigation water would be one- third of an acre-foot per acre. Calculations indicate that the maximum monthly rate of depletion due to the consumptive use of 4 inches of ground water per year on 500 acres would be about 0.4 cfs (cubic feet per second) the first year and 0.5 cfs after 10 years of pumping. Other computations indicate that the maximum monthly rate of depletion due to irrigating 500 acres the first year and 50 additional acres each year for 10 years would be about 0.8 cfs. Maximum depletion would occur during the summer months, concurrent with the irrigation withdrawals. Because of the close interrelation between ground and surface water, surface- water withdrawals will cause an increased inflow of ground water to the stream and a decline in ground-water levels near the stream. These effects were demonstrated by pumping from the stream. After 29 hours of pumping, a depletion of 1,120 gpm at a site 7,000 feet downstream was about 200 gpm less than the diversion at the pump. Most of the 200 gpm was supplied from the stream-banks, and ground-water levels near the stream declined as much as 0.3 foot. Computations indicated that ground-water inflow, following a streamflow diver- sion that lowered the stage 0.15 foot, would be 0.14 cfs after 5 days and 0.06 cfs after 30 days. The demonstration of the quantitative relation between ground water and surface water, as given by this study, should provide a sound basis for planning water development to minimize conflicts of interest. The demonstrations also should provide a basis for drafting legislation that recognizes the interrelation of ground water and surface water. Because the geology and the hydrology are relatively uniform throughout the sand plains, many of the methods and hydrologic values determined for this detailed study of the Little Plover River basin may be applied to other basins in the sand-plain area.

Wisconsin↗

A simple daily soil-water balance model for estimating the spatial and temporal distribution of groundwater recharge in temperate humid areas

Quantifying the spatial and temporal distribution of natural groundwater recharge is usually a prerequisite for effective groundwater modeling and management. As flow models become increasingly utilized for management decisions, there is an increased need for simple, practical methods to delineate recharge zones and quantify recharge rates. Existing models for estimating recharge distributions are data intensive, require extensive parameterization, and take a significant investment of time in order to establish. The Wisconsin Geological and Natural History Survey (WGNHS) has developed a simple daily soil-water balance (SWB) model that uses readily available soil, land cover, topographic, and climatic data in conjunction with a geographic information system (GIS) to estimate the temporal and spatial distribution of groundwater recharge at the watershed scale for temperate humid areas. To demonstrate the methodology and the applicability and performance of the model, two case studies are presented: one for the forested Trout Lake watershed of north central Wisconsin, USA and the other for the urban-agricultural Pheasant Branch Creek watershed of south central Wisconsin, USA. Overall, the SWB model performs well and presents modelers and planners with a practical tool for providing recharge estimates for modeling and water resource planning purposes in humid areas. ?? Springer-Verlag 2007.

Hydrogeology Journal↗

Ground-water quality in Wisconsin through 1972

Ground water, a plentiful and largely underdeveloped resource of Wisconsin, has good to excellent chemical quality in most places. This resource is readily available in most parts of the State for municipal, industrial, and rural uses. In 1970, about 0.5 billion gallons of ground water a day was pumped in Wisconsin for all uses (Murray and Reeves, 1972). In addition, underground reservoirs discharge an average of 16 billion gallons per day of water of relatively constant temperature and uniform quality, which maintains the base flow of streams and the level of lakes (Holt, 1964).

Wisconsin↗

Chemical and biological status of lakes and streams in the upper midwest: assessment of acidic deposition effects

Many lakes in three areas in the Upper Midwest - northeastern Minnesota, northern Wisconsin, and the Upper Peninsula of Michigan - have low acid neutralizing capacity (ANC) and may be susceptible to change by acidic deposition. Northcentral Wisconsin and the Upper Peninsula of Michigan together contain about 150-300 acidic lakes (ANC ≤ 0), whereas none have been found in Minnesota. These acidic lakes are precipitation-dominated, Clearwater seepage lakes having small surface area, shallow depth, and low concentrations of dissolved organic carbon. The spatial distribution of these acidic lakes parallels a west to east gradient of increasing sulfate and hydrogen ion deposition. Several of these acidic lakes exhibit chemical characteristics and biological changes consistent with those observed elsewhere in waters reported to be acidified by acidic deposition. However, an hypothesis of recent lake acidification is not supported by analyses of either historical chemical data or diatom remains in lake sediments, and natural sources of acidity and alternative ecological processes have not been conclusively eliminated as causative factors. Streams in this three-state region have high ANC and appear to be insensitive to acidic deposition. The species richness and composition of lacustrine fish communities in the region are partly related to pH and associated chemical factors. Sport fishes considered acid-sensitive and of primary concern with regard to acidification include walleye, smallmouth bass, and black crappie. The fishery in at least one lake, Morgan Lake in Wisconsin (pH 4.6), may have declined because of acidification. Given the general lack of quantitative fishery data for acidic Wisconsin and Michigan lakes, however, more general conclusions concerning impacts or the absence of impacts of acidification on the region's fishery resources are not possible.

Minnesota;Wisconsin;Michigan↗

Geology and ground-water resources of Fond du Lac County, Wisconsin

The principal water-bearing rocks underlying Fond du Lac County, Wis., are sandstones of Cambrian and Ordovician age and dolomite of Silurian age. Other aquifers include dolomite of Ordovician age and sand. and gravel of Quaternary age. Crystalline rocks of Precambrian age, which underlie all the water-bearing formations, form a practically impermeable basement complex and yield little or no water to wells. Ground water is the source of all public and most private and industrial water supplies in the county. The municipalities and industries obtain water chiefly from wells that penetrate the sandstones of Cambrian and Ordorician age. The Platteville formation and Galena dolomite of Ordovician age and the Niagara dolomite of Silurian age supply water to most domestic and stock wells and to a few industrial wells. Several buried valleys in the bedrock surface contain water-bearing deposits of sand and gravel. The source of the ground water in Fond du Lac County is local precipitation. Recharge to the water-bearing beds occurs in most of the county but is greatest where the bedrock formations are near the surface. Ground water is discharged by seeps and springs, by evaporation and transpiration, and by wells. Ground-water levels in wells fluctuate in response to recharge and to natural discharge and pumping. In areas not affected by pumping, water levels generally decline through the summer months because of natural discharge and lack of recharge, recover slightly in the fall after the first killing frost, decline during the winter, and recover in the spring when recharge is greatest. In areas of heavy pumping, the water levels are lowest in late summer and highest in late winter. Water levels in wells in the Fond du Lac area were about 5 to 50 feet above the land surface in 1885, but they had declined to as low as 185 feet below the land surface by 1957. Coefficients of transmissibility and storage of the sandstones of Cambrian and Ordovician age were determined by making controlled aquifer tests at Fond du Lac. The coefficients were verified by comparing computed water-level declines with actual declines. The computed values were within about 30 percent of the actual values, a reasonable agreement for coefficients of this type. Probable declines of water levels by 1966 were computed, using the same coefficients of transmissibility and storage. If the distribution of wells and the rate of pumping remain the same in 1957-66 as they were in 1956, the water levels will decline about 5 feet more by 1966. If, however, the distribution of pumped wells remains the same but the pumping by the city of Fond du Lac increases at a uniform rate from the 3 mgd (million gallons per day) pumped in 1956 to 5 mgd in 1966, the water levels in 1966 will be at least 60 feet below those of 1956. Dispersal of wells to the northwest toward the recharge area would reduce the water-level declines. The results of pumping tests, of test holes tapping the Niagara dolomite indicate that wells producing at least 200 gpm (gallons per minute) could be developed east of the Niagara escarpment. The ground water in Fond do Lac County is, in general, a hard calcium and magnesium bicarbonate water, which contains excessive iron in some areas.

Wisconsin↗

Net energy payback and CO2 emissions from three midwestern wind farms: An update

This paper updates a life-cycle net energy analysis and carbon dioxide emissions analysis of three Midwestern utility-scale wind systems. Both the Energy Payback Ratio (EPR) and CO2 analysis results provide useful data for policy discussions regarding an efficient and low-carbon energy mix. The EPR is the amount of electrical energy produced for the lifetime of the power plant divided by the total amount of energy required to procure and transport the materials, build, operate, and decommission the power plants. The CO2 analysis for each power plant was calculated from the life-cycle energy input data. A previous study also analyzed coal and nuclear fission power plants. At the time of that study, two of the three wind systems had less than a full year of generation data to project the life-cycle energy production. This study updates the analysis of three wind systems with an additional four to eight years of operating data. The EPR for the utility-scale wind systems ranges from a low of 11 for a two-turbine system in Wisconsin to 28 for a 143-turbine system in southwestern Minnesota. The EPR is 11 for coal, 25 for fission with gas centrifuge enriched uranium and 7 for gaseous diffusion enriched uranium. The normalized CO2 emissions, in tonnes of CO2 per GW eh, ranges from 14 to 33 for the wind systems, 974 for coal, and 10 and 34 for nuclear fission using gas centrifuge and gaseous diffusion enriched uranium, respectively. ?? Springer Science+Business Media, LLC 2007.

Natural Resources Research↗

RAD (Resist-Accept-Direct) switch points and triggers for adaptation planning

Climate change is transforming ecosystems globally. The Resist-Accept-Direct (RAD) framework has gained traction within many natural resource management institutions to help consider the decision space in response to this transformation. Because RAD helps manage for directional change, RAD choices entail considering which RAD pathway to implement and for how long. For example, one may accept a slowly changing ecosystem, but at a certain point, decide to begin resisting or directing the change an ecosystem is experiencing. Alternatively, one may begin resisting an ecosystem transformation, but ultimately realize resistance is no longer feasible based on cost or efficacy. These choices are challenging and encompass broad domains of cultural, ecological, financial, organizational, public, regulatory, and technological considerations to determine when to switch RAD pathways. We introduce the concepts of RAD switch points and triggers to help support these decision processes. We illustrate these concepts using case studies on walleye ( Sander vitreus ) stocking decisions in Wisconsin, wildfire response in the Greater Yellowstone Ecosystem, and bull trout ( Salvelinus confluentus ) management in Oregon, USA. Synthesizing across these examples, we delineate key points for decision makers as they (iteratively) reevaluate among the RAD pathways as conditions continue to change.

Journal of Environmental Management↗

Regional groundwater-flow model of the Lake Michigan Basin in support of Great Lakes Basin water availability and use studies

A regional groundwater-flow model of the Lake Michigan Basin and surrounding areas has been developed in support of the Great Lakes Basin Pilot project under the U.S. Geological Survey's National Water Availability and Use Program. The transient 2-million-cell model incorporates multiple aquifers and pumping centers that create water-level drawdown that extends into deep saline waters. The 20-layer model simulates the exchange between a dense surface-water network and heterogeneous glacial deposits overlying stratified bedrock of the Wisconsin/Kankakee Arches and Michigan Basin in the Lower and Upper Peninsulas of Michigan; eastern Wisconsin; northern Indiana; and northeastern Illinois. The model is used to quantify changes in the groundwater system in response to pumping and variations in recharge from 1864 to 2005. Model results quantify the sources of water to major pumping centers, illustrate the dynamics of the groundwater system, and yield measures of water availability useful for water-resources management in the region. This report is a complete description of the methods and datasets used to develop the regional model, the underlying conceptual model, and model inputs, including specified values of material properties and the assignment of external and internal boundary conditions. The report also documents the application of the SEAWAT-2000 program for variable-density flow; it details the approach, advanced methods, and results associated with calibration through nonlinear regression using the PEST program; presents the water-level, drawdown, and groundwater flows for various geographic subregions and aquifer systems; and provides analyses of the effects of pumping from shallow and deep wells on sources of water to wells, the migration of groundwater divides, and direct and indirect groundwater discharge to Lake Michigan. The report considers the role of unconfined conditions at the regional scale as well as the influence of salinity on groundwater flow. Lastly, it describes several categories of limitations and discusses ways of extending the regional model to address issues at the local scale. Results of the simulations portray a regional groundwater-flow system that, over time, has largely maintained its natural predevelopment configuration but that locally has been strongly affected by well withdrawals. The quantity of rainfall in the Lake Michigan Basin and adjacent areas supports a dense surface-water network and recharge rates consistent with generally shallow water tables and predominantly shallow groundwater flow. At the regional scale, pumping has not caused major modifications of the shallow flow system, but it has resulted in decreases in base flow to streams and in direct discharge to Lake Michigan (about 2 percent of the groundwater discharged and about 0.5 cubic foot per second per mile of shoreline). On the other hand, well withdrawals have caused major reversals in regional flow patterns around pumping centers in deep, confined aquifers - most noticeably in the Cambrian-Ordovician aquifer system on the west side of Lake Michigan near the cities of Green Bay and Milwaukee in eastern Wisconsin, and around Chicago in northeastern Illinois, as well as in some shallow bedrock aquifers (for example, in the Marshall aquifer near Lansing, Mich.). The reversals in flow have been accompanied by large drawdowns with consequent local decrease in storage. On the west side of Lake Michigan, groundwater withdrawals have caused appreciable migration of the deep groundwater divides. Before the advent of pumping, the deep Lake Michigan groundwater-basin boundaries extended west of the Lake Michigan surface-water basin boundary, in some places by tens of miles. Over time, the pumping centers have replaced Lake Michigan as the regional sink for the deep flow system. The regional model is intended to support the framework pilot study of water availability and use for the Great Lakes Basin (Reeves, in press).

Illinois, Indiana, Michigan, Wisconsin↗

Water-quality assessment of part of the Upper Mississippi River Basin, Minnesota and Wisconsin - Ground-water quality in an agricultural area of Sherburne County, Minnesota, 1998

The quality of shallow ground water in a 75-mi 2 agricultural area of the Anoka Sand Plain aquifer in central Minnesota is described as part of the National Water Quality Assessment (NAWQA) Program - a national-scale assessment of the quality of water resources within large study units in various hydrologic settings. Data were collected during 1998 from 29 wells completed in the aquifer, which predominantly consists of surficial glacial sand and gravel sediments. The depth below land surface to the water table ranged from 3.3 to 44 ft (median of 15.5 ft). Ground water was of the calciummagnesium bicarbonate type. Ionic constituents also included sodium, sulfate, and chloride. Iron and manganese concentrations generally were not greater than their U.S. Environmental Protection Agency (USEPA) Secondary Maximum Contaminant Levels (300 and 50 ug/L, respectively). About 38 percent of 29 samples had nitrate-N (nitrogen) concentrations greater than the USEPA Maximum Contaminant Level (MCL) of 10 mg/L. About 72 percent of the samples had nitrate-N concentrations greater than the presumed natural background level of 3 mg/L. The maximum nitrate-N concentration was 47 mg/L. The median nitrate-N concentration of 7.1 mg/L, although not greater than the MCL, exceeded the natural background level. Nitrogen isotope ratios indicate that the sources of nitrate were commercial fertilizer and soil organic matter. Concentrations of total dissolved phosphorus and orthophosphate were generally less than 1 mg/L. About 86 percent of 29 samples had detectable concentrations of at least 1 of 13 pesticide compounds. The samples were analyzed for 83 pesticide compounds. Frequencies of detection of these compounds were: deethylatrazine-79 percent; atrazine-76 percent; metolachlor-41 percent; metribuzin and bentazon-21 percent; prometon-10 percent; tebuthiuron-7 percent; and alachlor, 2,6-diethylaniline, dicamba, dinoseb, malathion, and simazine-3 percent. The detected pesticide compounds had concentrations less than 1 ug/L. Detected compounds with USEPA MCLs (atrazine, bentazon, alachlor, dinoseb, and simazine) had concentrations less than their respective MCLs. About 50 percent of 20 samples analyzed for 86 volatile organic compounds (VOCs) had detectable concentrations of at least 1 of 7 VOCs. Frequencies of detection of these 7 VOCs were: 1,2,3,4-tetramethylbenzene-40 percent; and trichlorofluoromethane, styrene, chloromethane, benzene, methylbenzene, and trichloromethane-5 percent. The detected VOCs had concentrations less than 0.120 ug/L. Detected VOCs with USEPA MCLs - styrene, benzene, methylbenzene, and trichloromethane - were present at concentrations 2-4 orders of magnitude less than their respective MCLs. Tritium concentrations had a range of from 7.5 to 18.8 tritium units (TUs) and a median of 12.5 TUs. These concentrations indicate that the ground water predominantly recharged after testing of thermonuclear weapons during the early 1950's.

Minnesota↗

Will hunters steward wolves? A comment on Treves and Martin

As wolf conservation transitions away from federally sponsored protection and recovery toward sustainable management under state fish and game agencies, researchers and policymakers are interested to know what role hunters will play. Based upon hunters' responses to three recent surveys in Wisconsin and the northern Rockies, Treves and Martin question the assumption that hunters will steward wolves, noting that the majority of hunters that responded were unsupportive of wolf conservation. However, this conclusion largely depends upon what is meant by stewardship and what actions are required for wolves to be conserved. This article discusses the meaning of three concepts either explicitly or implicitly discussed by Treves and Martin—tolerance, acceptance, and stewardship—and offers a conceptual model of wildlife conservation behavior that clarifies the relationship among these concepts.

Society & Natural Resources: An International Jour↗

Water quality and the effects of changes in phosphorus loading to Muskellunge Lake, Vilas County, Wisconsin

Muskellunge Lake is a productive, eutrophic lake because of high nutrient loading. Historical data indicate that water quality has only slightly degraded since the early 1970s, possibly because of phosphorus input from effluent from septic systems. A detailed phosphorus budget for the lake indicated that most of the phosphorus comes from natural sources?ground water and surface water flowing through relatively undeveloped areas surrounding the lake. Modeling results indicated that the natural input of phosphorus was sufficient to maintain the lake's eutrophic condition. Analysis of sediment cores confirmed that only small changes in nutrient and algal concentrations have occurred over the past 100 years; however, the analysis indicated that the macrophyte community has increased over this time period. The aeration system, installed to alleviate winter anoxia, maintains aerobic conditions throughout the main bays of the lake.

Wisconsin↗

Quantity, structure, and habitat selection of natural spawning reefs by walleyes in a north temperate lake: A multiscale analysis

Spawning habitat, the cornerstone of self-sustaining, naturally reproducing walleye Sander vitreus populations, has received limited quantitative research. Our goal was to quantitatively describe the structure and quantity of natural walleye spawning habitat and evaluate potential selection of habitat in Big Crooked Lake, Wisconsin. In 2004 and 2005, we located and delineated walleye egg deposition polygons through visual snorkel and scuba surveys. We also delineated recently deposited, adhesive egg patches daily along one spawning reef in 2005. To determine habitat selection, we quantified and compared spawning and lakewide available habitat at different scales. In both years, walleyes used similar spawning habitat, including three geomorphic types: linear shorelines, a point bar, and an island. Walleyes used only 14% of the entire lake shoreline and 39% of the shoreline comprised of gravel (6.4–76.0 mm), cobble (76.1–149.9 mm), or coarser substrates for spawning in 2005, indicating selection of specific spawning habitat. Lakewide, walleyes spawned close to shore (outer egg deposition polygon boundary mean distance = 2.7 m), in shallow water (outer egg deposition polygon boundary mean depth = 0.3 m), and over gravel substrate (percent coverage mean = 64.3) having low embeddedness (mean = 1.30). Our best nearshore (0–13-m) resource selection function predicted an increase in the relative probability of egg deposition with the increasing abundance of gravel, cobble, and rubble (150.0–303.9-mm) substrates and a decrease with increasing distance from shore and water depth (89.9% overall correct classification). Adhesive egg patches confirmed that walleyes actively chose nearshore, shallow-water, and coarse-substrate spawning habitat. The quantitative habitat information and predictive models will assist biologists in developing walleye spawning reef protection strategies and potentially aid in designing and evaluating artificial spawning reefs.

Wisconsin↗

Land use effects on sediment nutrient processes in a heavily modified watershed using structural equation models

Contemporary land use can affect sediment nutrient processes in rivers draining heavily modified watersheds; however, studies linking land use to sediment nutrient processes in large river networks are limited. In this study, we developed and evaluated structural equation models (SE models) for denitrification and phosphorus retention capacity to determine direct and indirect linkages between current land use and sediment nutrient processes during baseflow in the Fox River watershed, Wisconsin USA. A large spatial-scale dataset used for this study included sediment nitrogen and phosphorus retention measurements and land use information for 106 sites. The SE models for the Fox River watershed identified direct links between current land use and in-stream sediment nutrient processes. Sub-watersheds with agricultural land consisting of more natural land cover had lower surface water nitrate concentrations and higher denitrification enzyme activity than sub-watersheds with less alternative cover. This suggests that best management practices implemented in the Fox River watershed that restore natural land cover can improve water quality through nitrogen removal on the agricultural landscape and in the river network. Best management practices are not having the same measurable affect on phosphorus in the river network, most likely due to legacy phosphorus stored in the sediment.

Wisconsin↗