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Research about Wisconsin

Source-linked reports with geographic coverage including Wisconsin.

At least 685 records · Page 38Linked to original sources
USGS1990

Identification of isopropylbiphenyl, alkyl diphenylmethanes, diisopropylnaphthalene, linear alkyl benzenes and other polychlorinated biphenyl replacement compounds in effluents, sediments and fish in the Fox River System, Wisconsin

Five polychlorinated biphenyl replacement dye solvents and a diluent present in carbonless copy paper were identified by gas chromatography/mass spectrometry in the following matrices: effluents from a de-inking–recycling paper mill and a municipal wastewater treatment plant receiving wastewaters from a carbonless copy paper manufacturing plant; sediments; and fish collected near both discharges in the Fox River System, Wisconsin. An isopropylbiphenyl dye solvent mixture included mono-, di- and triisopropylbiphenyls. Also identified were two dye solvent mixtures marketed under the trade name Santosol. Santosol 100 comprised ethyl-diphenylmethanes (DPMs), benzyl-ethyl-DPMs, and dibenzyl-ethyl-DPMs. Similarly, Santosol 150 comprised dimethyl-DPMs, benzyl-dimethyl-DPMs, and dibenzyl-dimethyl-DPMs. Diisopropylnaphthalenes, widely used as a dye solvent in Japan, were identified for the first time in the US environment. sec -Butylbiphenyls and di- sec -butylbiphenyls, likely constituents of a sec -butylbiphenyl dye solvent mixture, were tentatively identified. Linear alkyl benzenes (C 10 to C 13 -LABs) constituted the Alkylate 215 diluent mixture. Although known to occur as minor constituents in linear alkyl sulfonate detergents, LAB residues have not been previously attributed to commercial use of LABs.

Wisconsin↗
USGS1990

Benefit-cost analysis of fishery rehabilitation projects: A Great Lakes case study

Tools of benefit-cost analysis are used to evaluate a project to rehabilitate the yellow perch fishery of Green Bay, Wisconsin. Both sport and commercial fishers harvest from this stock, which has been suffering from much reduced productivity since the early 1960s. The project is composed of commercial quotas and other regulations. Measures of benefits and costs were used that explicitly incorporate uncertainty about the potential level of success of the project. The analysis shows that commercial fish producers will more or less break even compared to where they would have been without the project, but that substantial recreational benefits can be expected. This case study illustrates how benefit-cost analysis can provide useful insights into the potential economic returns from rehabilitation projects. It also dramatizes unresolved research issues, particularly in the area of sport fishing valuation.

Wisconsin↗
USGS1990

Precambrian terrane of north-central Wisconsin: an aeromagnetic perspective

A shaded relief magnetic map covering most of the region of exposed Precambrian rocks of north-central Wisconsin shows the structural grain and many lithologic units with clarity and comprehensive detail. The area includes part of the volcanic sequence of the Keweenawan Supergroup south of Lake Superior, the southern margin of the Archean Superior Province, the accreted island-arc terranes of the Penokean Orogen, and the Wolf River batholith. Numerous dikes are evident in the shaded relief, some being more than 200 km in length. Many of the longer dikes are reversely magnetized Keweenawan diabase associated with early extension of the Midcontinent Rift; some apparently were intruded along preexisting faults. A northwest system of dikes and faults indicated by the shaded relief map may be related to later stages of Keweenawan rifting. The Wolf River batholith is characterized by low magnetic relief associated with the predominant granitoids but includes circular plutons of highly magnetic anorthosite and a large area of magnetic rock having a signature different from the mapped anorthosite bodies. A fault bounding the western side of the batholith is paralleled by an apparent system of faults or dikes in the older terrane to the west. The magnetic map covering the Wisconsin magmatic terranes and the Archean Superior Province margin to the north is dominated by east-northeast-trending Penokean rocks. Large units of magnetic mafic rocks and less magnetic granitoid rocks are cut by a system of well-defined northeast shear zones and a more easterly trending, possibly younger set of faults, some of which contain dikes along parts of their lengths. Although the sutures bounding the magmatic terranes generally follow the magnetic trends, they do not have distinctive magnetic signatures.

Wisconsin↗
USGS1990

Factors influencing mercury concentrations in walleyes in northern Wisconsin lakes

We examined relations between mercury concentrations in walleyes Stizostedion vitreum and the characteristics ofclear‐water Wisconsin lakes, which spanned a broad range of pH values (5.0–8.1) and acid‐neutralizing capacities (–9 to 1,017 μeq/L). Total concentrations of mercury in axial muscle tissue of walleyes (total length, 25–56 cm) varied from 0.12 to 1.74 μg/g wet weight. Concentrations were greatest in fish from the eight lakes with pH less than 7.0; concentrations in these fish equaled or exceeded 0.5 μg/g in 88% of the samples analyzed and 1.0 μg/g in 44%. In the five lakes with pH of 7.0 and above, concentrations exceeded 0.5 μg/g in only 1 of 21 walleyes. Multiple regression revealed that lake pH and total length offish accounted for 69% of the variation in mercury concentration in walleyes. Regression models with total length and either waterborne calcium or acid‐neutralizing capacity as independent variables accounted for 67% of the variation in concentration. The observed differences in fish mercury concentration between the low‐pH and high‐pH lakes could not be logically attributed to differences in growth rate or diet among the walleye populations. Moreover, it is improbable that mercury influxes to the low‐pH lakes were greater than those to the high‐pH lakes, because of the close proximity and spatial interspersion of low‐ and high‐pH lakes. We attributed the observed pH‐related trend in mercury concentration in walleyes to variation among lakes in within‐lake processes that affected the production and bioavailability of methylmercury.

Wisconsin↗
USGS1990

Data on polychlorinated biphenyls, dieldrin, lead, and cadmium in Wisconsin and Upper Michigan tributaries to Green Bay, July 1987 through April 1988

A reconnaissance study was conducted of 22 streams tributary to Green Bay to determine whether any of the streams contribute toxic substances to the bay. This effort was part of a comprehensive investigation of Green Bay funded by the U.S. Environmental Protection Agency, Great Lakes National Program Office. The U.S. Geological Survey sampled the bottom sediments and water columns of 11 streams tributary to western Green Bay for polychlorinated biphenyls, lead, and cadmium. Four of these streams also were sampled for dieldrin, a pesticide previously used in the watershed. An additional 11 streams tributary to eastern Green Bay were sampled for dieldrin in the bottom sediment and storm runoff. Samples were collected from July 1987 through April 1988. Neither dieldrin nor cadmium was detected in any of the sampled tributaries. Detectable concentrations of polychlorinated biphenyls and lead were found at only three sites. Polychorinated biphenyls (0.10 microgram per gram) and lead (10 milligrams per kilogram) were found in the bottom sediment of Duck Creek, a western-shore tributary near the city of Green Bay. Lead (10 milligrams per kilogram) also was found in the bottom sediment of the Suamico River near the mouth, about 5 miles north of Duck Creek. Lead (4 micrograms per liter) was detected in a spring-runoff sample from the Fishdam River, a tributary from upper Michigan.

Wisconsin↗
USGS1990

Hydrology, aquatic macrophytes, and water quality of Black Earth Creek and its tributaries, Dane County, Wisconsin, 1985-86

An intensive data-collection program for the Black Earth Creek basin in southern Wisconsin was conducted from October 1984 through September 1986 to assess the hydrology, aquatic macrophytes, and water quality in Black Earth Creek by the U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources. Three sites on two cold-water trout streams Black Earth Creek at Cross Plains, Black Earth Creek near Cross Plains, and Garfoot Creek near Cross Plains were continuously monitored for streamflow and water-quality data. One site in a warm-water stream, Brewery Creek at Cross Plains, also was monitored. Aquatic macrophyte biomass was determined for three sites on Black Earth Creek. Streamflow at Black Earth Creek at Black Earth during the 1985 and 1986 water years (WY) were 44 and 60 percent greater than the long-term mean discharge of 33.3 ft3/s (cubic feet per second) for the period 1955-86. Water year 1986 had the highest annual mean discharge, 53.4 ft3/s, since records began in 1954 at the most downstream site Black Earth Creek at Black Earth. Although there have been considerable fluctuations in streamflow, it has tended to increase since WY 1965 as a result of above-average precipitation and consequent rising ground-water levels. Trout population densities may be related to annual mean streamflow. A regression analysis of adult trout populations and the 3-year moving annual mean discharge had a correlation coefficient of 0.75 with a standard error of 83 percent. Aquatic macrophyte biomass in Black Earth Creek was substantially less in 1986 than in 1985 as a result of substrate scouring from the flood of July 25, 1985. The frequency of occurrence of species during 1985 and 1986 was similar to that of 1981, and seasonal succession of species also was similar; Potamogeton crispus dominated early in the year and senesced in July. P. crispus and P. pectinatus, both indicative of eutrophic conditions, dominated upstream and downstream, respectively; neither species is native to the area. In 1985, the greatest biomass was found upstream from Cross Plains. This large biomass caused diurnal fluctuations in dissolved-oxygen concentration of 5 to 6 mg/L (milligrams per liter) as a result of photosynthesis and respiration. Many of the dissolved-oxygen minimums, recorded at night, were less than the State 6.0-mg/L water-quality standard for trout waters. Discharge from point sources may adversely affect Black Earth Creek's water quality. Warm water discharged to Black Earth Creek from a gravel pit operation upstream from Cross Plains increased water temperatures 2 to 4 degrees Celsius and decreased the dissolved oxygen about 1 mg/L at a site 1.8 miles downstream. Runoff from a settling pond from a landfill operation in the headwaters of the Black Earth Creek basin drains through a wetland that drains to Black Earth Creek and contained as much as 60 mg/L ammonia nitrogen, 980 mg/L biochemical oxygen demand, and 1,300 mg/L chemical oxygen demand, which may be detrimental to trout. Garfoot Creek had the highest suspended-sediment and phosphorus yields per unit area of the three upstream basins during low to moderate runoff. Detention ponds in the Brewery Creek basin appear to be less effective in controlling suspended-sediment and phosphorus loads during periods of high runoff than during moderate runoff. Brewery Creek had the highest concentrations of suspended sediment and total phosphorus during low and high flows. The water quality at the Black Earth Creek gaging station at Black Earth was affected by Garfoot Creek and unnamed tributaries. As a result, yields of suspended sediment, phosphorus, and nitrogen increased between Cross Plains and Black Earth. High streamflows during WY 1985 resulted in suspendedsediment yields at Black Earth Creek at Black Earth that were 29 percent greater than the 12-year (1955-65, 85-86) mean; yields ranged from 69.5 ton/mi2 (tons per square mile) in Black Earth Creek at Cross Plains to 116 ton/mi2 in the Brewery Creek basin. Phosphorus yields ranged from 312 lb/mi2 (pounds per square mile) in Black Earth Creek at Cross Plains to 628 lb/mi2 in the Brewery Creek basin. Total nitrogen yields ranged from 3,280 lb/mi2 in the Brewery Creek basin to 6,920 lb/mi2 in the Garfoot Creek basin. An increase in oxygen demand, caused by agricultural runoff, has resulted in reduced dissolved-oxygen content of the water in both Black Earth and Garfoot Creeks. The most substantial reduction occurred at Black Earth Creek at Cross Plains on July 25, 1985, as a result of the largest storm runoff event during the study. A rainfall of 5.54 inches caused streamflow discharges to increase from 9 to 122 ft3/s and dissolved-oxygen concentrations to decline to 3.0 mg/L; the dissolved-oxygen concentration was less than 6.0 mg/L for 30 hours.

Wisconsin↗
USGS1989

Interrelationships among hydrologic-budget components of a northern Wisconsin seepage lake and implications for acid-deposition modeling

Components of the hydrologic budget for a northern Wisconsin seepage lake were analyzed by applying correlation and regression techniques to monthly data. Analyses for the 1981–83 water years revealed a statistically significant, direct relationship between storage change and precipitation-evaporation balance. Ground-water outflow was negatively correlated with ground-water inflow, and this relationship was influenced by similar relationships for both hydraulic gradients and cross-sectional areas in outflow versus inflow regions of the lake. Neither ground-water outflow nor inflow was significantly related to precipitation, evaporation, storage change, or lake stage; this may reflect a lag in response time of the ground-water system compared to the lake. The results (1) emphasize the complexity of factors that influence ground-water interactions with seepage lakes and (2) suggest the importance of completing detailed hydrologic studies of these systems before mechanistic models, such as those developed to predict effects of acid deposition, are applied.

Wisconsin↗
USGS1989

Recent increases in atmospheric deposition of mercury to North-Central Wisconsin lakes inferred from sediment analyses

Profiles of total mercury (Hg) concentrations in sediments were examined in 11 lakes in north-central Wisconsin having a broad range of pH (5.1 to 7.8) and alkalinity (-12 to 769 μeq/L). Mercury concentrations were greatest in the top 15 cm of the cores and were much lower in the deeper strata. The Hg content in the most enriched stratum of individual cores ranged from 0.09 to 0.24 μg/g dry weight, whereas concentrations in deep, precolonial strata ranged from 0.04 to 0.07 μg/g. Sediment enrichment factors varied from 0.8 to 2.8 and were not correlated with lake pH. The increase in the Hg content of recent sediments was attributed to increased atmospheric deposition of the metal. Eight of the 11 systems studied were low-alkalinity lakes that presumably received most (≥90%) of their hydrologic input from precipitation falling directly onto the lake surface. Thus, the sedimentary Hg in these lakes seems more likely linked to direct atmospheric deposition onto the lake surfaces than to influxes from the watershed. The data imply that a potentially significant fraction of the high Hg burdens measured in game fish in certain lakes in north-central Wisconsin originated from atmospheric sources.

Wisconsin↗
USGS1989

Microcontaminants and reproductive impairment of the Forster's tern on Green Bay, Lake Michigan,1983

For the 1983 nesting season, Forster's tern ( Sterna forsteri ) reproductive success was significantly impaired on organochlorine contaminated Green Bay, Lake Michigan compared to a relatively uncontaminated inland location at Lake Poygan, Wisconsin. Compared with tern eggs from Lake Poygan, eggs from Green Bay had significantly higher median concentrations of 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), other polychlorinated dibenzo- p -dioxins (PCDDs), total polychlorinated biphenyls (PCBs), total (three congeners) non-ortho, ortho' PCBs, five individual PCB congeners known to induce aryl hydrocarbon hydroxylase (AHH) and several other organochlorine contaminants. Conversions of analytical concentrations of TCDD and PCB congeners based on relative AHH induction potencies allowed for estimation of total 2,3,7,8-TCDD equivalents. Two PCB congeners, 2,3,3′,4,4′- and 3,3′,4,4′,5-pentachlorobiphenyl (PeCB) accounted for more than 90% of the median estimated TCDD equivalents at both Green Bay and Lake Poygan. The median estimated TCDD equivalents were almost 11-fold higher in tern eggs from Green Bay than in eggs from Lake Poygan (2175 and 201 pg/g). The hatching success of Green Bay sibling eggs from nests where eggs were collected for contaminant analyses was 75% lower at Green Bay than at Lake Poygan. Hatchability of eggs taken from other nests and artificially incubated was about 50% lower for Green Bay than for Lake Poygan. Among hatchlings from laboratory incubation, those from Green Bay weighed approximately 20% less and had a mean liver weight to body weight ratio 26% greater than those from Lake Poygan. In both field and laboratory, mean minimum incubation periods were significantly longer for eggs from Green Bay compared to Lake Poygan (8.25 and 4.58 days, respectively). Mean minimum incubation time for Green Bay eggs in the field was 4.37 days longer than in the laboratory. Hatchability was greatly improved when Green Bay eggs were incubated by Lake Poygan adults in an egg-exchange experiment, but was sharply decreased in Lake Poygan eggs incubated in Green Bay nests. Nest abandonment and egg disappearance were substantial at Green Bay but nil at Lake Poygan. Thus, not only factors intrinsic to the egg, but also extrinsic factors (parental attentiveness), impaired reproductive outcome at Green Bay. The epidemiological evidence from this study strongly suggested that contaminants were a causal factor. AHH-active PCB congeners (intrinsic effects) and PCBs in general (extrinsic effects) appeared to be the only contaminants at the concentrations measured in eggs, capable of producing the effects that were observed at Green Bay.

Wisconsin↗
USGS1989

Late Wisconsin landform distribution and glacier-bed conditions in Wisconsin

The late Wisconsin Laurentide Ice Sheet advanced across permafrost and reached its maximum extent in Wisconsin between about 18,000 and 15,000 years ago. Deep permafrost persisted in southern Wisconsin until about 14,000 years ago and in northern Wisconsin until about 13,000 years ago. We suggest that during maximum glaciation a zone about 5 km wide in the south and 20 km wide in the north along the margin of the late Wisconsin glacier was frozen to its bed. Meltwater from farther behind the margin, where the bed was at least locally thawed, cut a series of closely spaced tunnel channels through the frozen-bed zone. These channels most likely formed episodically, and they were the source for much of the meltwater-stream sediment deposited in broad outwash plains beyond the ice margin. Frozen-bed conditions near the margin also likely contributed to increased upward shearing of sediment and the accumulation of thicl supraglacial sediment in northern areas. Up ice from the frozen-bed zone the glacier bed was at least locally thawed in a zone about 75 km wide. Extensive drumlin fields formed in the area of the bed that was thawed. By about 13,000 years ago permafrost melted in northern Wisconsin and thawed-bed conditions probably extended to the ice margin throughout Wisconsin and adjacent areas. After about 13,000 years ago in northern Wisconsin the glacier was sliding on its bed and forming drumlins out to the ice margin, and thick supraglacial sediment no longer accumulated.

Wisconsin↗
USGS1989

A macrophyte submodel for aquatic ecosystems

A macrophyte submodel has been incorporated and tested in CE-QUAL-R1, a one-dimensional, vertically averaged model of reservoir water quality. A quasi two-dimensional scheme was necessary to represent the spatial relationship of macrophytes in reservoirs adequately. The macrophyte processes modeled were photosynthesis, dark respiration, excretion and nonpredatory mortality. Process equations for photosynthesis as a function of light and temperature, and dark respiration as a function of temperature were tested using data from laboratory studies. The submodel was field tested, along with other components of CE-QUAL-R1, using data collected at Eau Galle Reservoir, WI, U.S.A.

Wisconsin↗
USGS1989

Replacement of native oak and hickory tree species by the introduced American chestnut (Castanea dentata) in southwestern Wisconsin

American chestnut was introduced at West Salem, Wisconsin, about 1880 and had begun to replace native tree species in adjacent oak-hickory woodland before 1930. Chestnut is now an important canopy species over about 20 ha of forested ridge extending north and south of the original plantation. A smaller area of less than 5 ha is dominated by chestnut in both the canopy and understory. Chestnut seedlings and small saplings are more numerous along woodland edges and in recently disturbed soil, they are rare in the interior of ungrazed pasture and entirely absent from intensively grazed areas adjacent to chestnut-dominated woodland. Random sampling of recently established seedlings indicates that from 1 to 5 seedlings/(year ∙ ha) became established in undisturbed woodland between 1986 and 1988. The general pattern of chestnut distribution indicates the importance of woodland edges in chestnut propagation and the effects of livestock grazing in excluding chestnut. Replacement of native species by chestnut appears to have occurred in two steps: isolated groups of trees became established at favorable locations, after which many additional chestnut stems became established in the understory. The recent discovery and treatment of blight indicates that the West Salem site may not be available for study of blight-free chestnut in the future.

Wisconsin↗
USGS1989

Tectono-stratigraphic evolution of the Early Proterozoic Wisconsin magmatic terranes of the Penokean Orogen

The Early Proterozoic Penokean Orogen developed along the southern margin of the Archean Superior craton. The orogen consists of a northern deformed continental margin prism overlying an Archean basement and a southern assemblage of oceanic arcs, the Wisconsin magmatic terranes. The south-dipping Niagara fault (suture) zone separates the south-facing continental margin from the accreted arc terranes. The suture zone contains a dismembered ophiolite.The Wisconsin magmatic terranes consist of two terranes that are distinguished on the basis of lithology and structure. The northern Pembine–Wausau terrane contains a major succession of tholeiitic and calc-alkaline volcanic rocks deposited in the interval 1860–1889 Ma and a more restricted succession of calc-alkaline volcanic rocks deposited about 1835 – 1845 Ma. Granitoid rocks ranging in age from about 1870 to 1760 Ma intrude the volcanic rocks. The older succession was generated as island arcs and (or) closed back-arc basins above the south-dipping subduction zone (Niagara fault zone), whereas the younger one developed as island arcs above a north-dipping subduction zone, the Eau Pleine shear zone. The northward subduction followed deformation related to arc–continent collision at the Niagara suture at about 1860 Ma. The southern Marshfield terrane contains remnants of mafic to felsic volcanic rocks about 1860 Ma that were deposited on Archean gneiss basement, foliated tonalite to granite bodies ranging in age from about 1890 to 1870 Ma, and younger undated granite plutons. Following amalgamation of the two arc terranes along the Eau Pleine suture at about 1840 Ma, intraplate magmatism (1835 Ma) produced rhyolite and anorogenic alkali-feldspar granite that straddled the internal suture.

Wisconsin↗
USGS1989

Hydrogeology of Wood County, Wisconsin

The presence of low-permeability Precambrian rocks near land surface limits ground-water availability in the northern two-thirds of Wood County. Sand and gravel deposits provide large amounts of water (more than 500 gallons per minute) to some wells in the southeastern part of the county. Fine-grained unconsolidated deposits generally are less than 20 feet thick in the northern two-thirds of the county, but sand and gravel deposits 40- to 100-feet thick underlie the extreme southeastern part of the county. Horizontal hydraulic conductivity of the sand and gravel deposits ranges from about 155 to about 280 feet per day. The horizontal hydraulic conductivity of fine-grained unconsolidated deposits in the northern part of the county ranges from about 0.02 to 2 feet per day. Where unconsolidated deposits do not yield dependable water supplies, wells are finished in Precambrian rocks. Fractures occurring at shallow depths are the primary source of water for wells finished in Precambrian rocks. Because the number of fractures tends to decrease with depth, the horizontal hydraulic conductivity of these rocks generally decreases from about 11 feet per day in wells less than 50-feet deep to about 0.02 foot per day in wells greater than 160 feet deep. Estimates of ground-water recharge to sand and gravel deposits in the southeastern part of the county range from about 7 to 12 inches per year. Recharge estimates for the central and northern parts of the county range from about 1 to 4 inches per year. The total dissolved-solids concentration in ground water in Wood County is relatively low. Concentrations in water samples from 124 wells ranged from 21 to 578 milligrams per liter, with a median concentration of about 190 milligrams per liter. Major dissolved constituents are calcium, magnesium, and bicarbonate; sodium, potassium, chloride, and sulfate are present in low concentrations. The most common water-quality problem in Wood County is elevated iron concentrations. Iron concentrations greater than 300 micrograms per liter were found in 54 of 124 samples, and 15 samples contained iron concentrations greater than 5,000 micrograms per liter. Nitrate as nitrogen concentrations exceeded Wisconsin's drinking-water standard (10 milligrams per liter) in water from just 4 of 124 wells. The pesticide aldicarb was detected in 7 of 36 samples, and various volatile organic compounds were detected in 24 of 102 ground-water samples collected by the Wisconsin Department of Natural Resources since 1980. Wells in which these chemicals were detected are near irrigated agricultural fields and in commercially developed areas where buried gasoline-storage tanks and chemical spills are more likely to occur. A reconnaissance approach combining electromagnetic surveys and sampling for water-quality indicators was used to assess effects of leachate on ground water near seven landfills. Results of the electromagnetic surveys were used to site water-quality observation wells. Total dissolved-solids concentrations and concentrations of volatile organic compounds, chloride, sulfate, iron, chemical oxygen demand, and organic carbon are some of the chemical constituents analyzed in samples collected from these wells. The average rate of ground·water pumpage in Wood County in 1985 was 9.7 million gallons per day. Of this rate, about 6 million gallons per day is pumped from municipal-supply wells in seven communities.An additional 1.08 million gallons per day is pumped for agricultural irrigation.

Wisconsin↗
USGS1988

U.S. Geological Survey ground-water studies in Wisconsin

GROUND-WATER ISSUES Ground-water sources provide about one-half of the water used in Wisconsin, excluding the water used for thermoelectric cooling. Ground-water sources serve about 70 percent of the State's population. All rural-domestic supplies and about 94 percent of the municipalities use ground water. Nearly all irrigation and stock watering are from ground water. Aquifers in Wisconsin are grouped into three principal types the sandstone aquifer, the Silurian-dolomite aquifer, and the sand-and-gravel aquifer. The sandstone aquifer underlies the southern two-thirds of the State and includes numerous rock formations, mostly sandstone and dolomite. Water in this aquifer usually is very hard. The Silurian-dolomite aquifer is found only along the area near Lake Michigan where it underlies the sandandgravel aquifer. Ground water in the Silurian-dolomite aquifer is the hardest of all ground water in Wisconsin and usually can benefit from softening. The sand-and-gravel aquifer is mostly permeable unconsolidated sediments in stream-valley alluvium and glacial deposits. The glacial deposits cover much of the State's land surface. Water from the sand-and-gravel aquifer is acceptable for nearly all uses. Changes in land and water use have caused increasing concerns about water supplies, water quality, water-related environmental conditions, and water management. The major ground-water issues in the State are related to: Availability, Point and nonpoint pollution, and Natural water quality.

Wisconsin↗