Geology topics

Research about Brown County, Wisconsin

Source-linked reports with geographic coverage including Brown County, Wisconsin.

5 recordsLinked to original sources

USGS1999

Organochlorine contaminants and reproductive success of double-crested cormorants from Green Bay, Wisconsin, USA

In 1994 and 1995, nesting success of double-crested cormorants ( Phalacrocorax auritus ) was measured at Cat Island, in southern Green Bay, Lake Michigan, Wisconsin, USA. Sample eggs at pipping and unhatched eggs were collected and analyzed for organochlorines (including total polychlorinated biphenyls [PCBs] and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in embryos, and eggshell thickness. Of 1,570 eggs laid, 32% did not hatch and 0.4% had deformed embryos. Of 632 chicks monitored from hatching to 12 d of age, 9% were missing or found dead; no deformities were observed. The PCB concentrations in sample eggs from clutches with deformed embryos (mean = 10.2 μg/g wet weight) and dead embryos (11.4 μg/g) were not significantly higher than concentrations in sample eggs from nests where all eggs hatched (12.1 μg/g). A logistic regression of hatching success versus DDE, dieldrin, and PCB concentrations in sibling eggs identified DDE and not dieldrin or PCBs as a significant risk factor. A logistic regression of hatching success versus DDE and eggshell thickness implicated DDE and not eggshell thickness as a significant risk factor. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in double-crested cormorant eggs in Green Bay are still having an effect on reproduction in this species.

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USGS1999

Hydrogeologic properties of the Ordovician Sinnipee Group at test well BN-483, Better Brite Superfund Site, De Pere, Wisconsin

Test well BN-483, near the Better Brite Superfund Site, was drilled to a total depth of 169 feet below land surface. The Ordovician-age Sinnipee Group, which includes the Galena Dolomite, and the Decorah and Platteville Formations, was encountered from about 25 feet below land surface to a depth of about 160 feet. Analysis of core samples and single-well aquifer tests of the dolomites indicate low matrix porosity (1.8 to 7.7 percent) and low horizontal hydraulic conductivity (5.0 x 10 -4 to 3.4 x 10 -3 feet per day). Significant differences in hydraulic head between Sinnipee Group dolomites and the underlying Sandstone Aquifer (represented by the Glenwood Formation sandstones in test well BN-483) are the result of municipal pumping from the Sandstone Aquifer. The difference in hydraulic head, along with the low porosity and hydraulic conductivity of the Sinnipee Group dolomites, indicates limited hydraulic connection between the Sandstone Aquifer and the shallow aquifer within the glacial sediments. Because of the low hydraulic conductivity of the dolomites, sufficient water for analysis was recovered from only the uppermost interval of test well BN-483 at a depth of 35-52 feet. No inorganic contaminants of environmental concern were detected. Toluene was the only VOC identified, at an estimated concentration of about 2 micrograms/liter.

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USGS1998

Optimization of ground-water withdrawal in the lower Fox River communities, Wisconsin

Pumping from closely spaced wells in the Central Brown County area and the Fox Cities area near the north shore of Lake Winnebago has resulted in the formation of deep cones of depression in the vicinity of the two pumping centers. Water-level measurements indicate there has been a steady decline in water levels in the vicinity of these two pumping centers for the past 50 years. This report describes the use of ground-water optimization modeling to efficiently allocate the ground-water resources in the Lower Fox River Valley. A 3-dimensional ground-water flow model was used along with optimization techniques to determine the optimal withdrawal rates for a variety of management alternatives. The simulations were conducted separately for the Central Brown County area and the Fox Cities area. For all simulations, the objective of the optimization was to maximize total ground-water withdrawals. The results indicate that ground water can supply nearly all of the projected 2030 demand for Central Brown County municipalities if all of the wells are managed (including the city of Green Bay), 8 new wells are installed, and the water-levels are allowed to decline to 100 ft below the bottom of the confining unit. Ground water can supply nearly all of the projected 2030 demand for the Fox Cities if the municipalities in Central Brown County convert to surface water; if Central Brown County municipalities follow the optimized strategy described above, there will be a considerable shortfall of available ground water for the Fox Cities communities. Relaxing the water-level constraint in a few wells, however, would likely result in increased availability of water. In all cases examined, optimization alternatives result in a rebound of the steady-state water levels due to projected 2030 withdrawal rates to levels at or near the bottom of the confining unit, resulting in increased well capacity. Because the simulations are steady-state, if all of the conditions of the model remain the same these withdrawal rates would be sustainable in perpetuity.

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USGS1986

Hydrogeology and ground-water use and quality, Brown County, Wisconsin

The Paleozoic rock of Brown County includes formations of Cambrian, Ordovician, and Silurian age. These formations are eastward-dipping sedimentary rock that rest on Precambrian crystalline rock and are overlain by Pleistocene deposits. The units that are the principal sources of ground water were grouped into three aquifers (upper, St. Peter, and Elk Mound), and the less permeable units are grouped into three confining units (Maquoketa-Sinnipee, St. Lawrence, and Precambrian). The geologic and hydraulic characteristics of the aquifers and confining units are estimated from logs of more than 1,000 Brown County wells, from results of a packer test, and from published values. Recharge to the water table, which was estimated at five monitored sites, ranges from 1 to 6 inches a year; most recharge is contributed by spring snowmelt and rainfall. A cone of depression caused by pumping the deeper aquifers in the Green Bay metropolitan area induces flow from the upper aquifer to the underlying st. Peter aquifer throughout most of the county. Several reaches of Duck Creek and the Suamico River also contribute water to the aquifers. A bout 13 million gallons per day of ground water was pumped in Brown County during 1979, 63 percent of which was from wells open to both the St. Peter and Elk Mound aquifers. Municipal and industrial water users pumped 9.44 million gallons per day or 72 percent of the ground water withdrawn in 1979. Most ground :water in the county is a calcium magnesium bicarbonate type. However, water from wells sampled in an area between the Fox River and Silurian escarpment have elevated levels of sodium (44 milligrams per liter) and sulfate (226 milligrams per liter). Water from wells that tap rocks older than Silurian dolomite contains high concentrations of strontium (more than 2.4 milligrams per liter) and fluoride (more than 0.85 milligrams per liter). A three-dimensional digital model was used to simulate flow in the ground-water system. Model results indicate that sources of ground water pumped from wells tapping the St. Peter and Elk Mound aquifers in Brown County, 1979, include 4.8 million gallons per day of underflow, most of which enters the county across the west border; 1.9 million gallons per day of flow from vertical leakage within the county; and 1.5 million gallons per day from storage. The model is most sensitive to the horizontal hydraulic conductivity of the upper aquifer. Vertical hydraulic conductivity of the confining units and recharge rates to the water-table aquifer are the least well-defined model parameters.

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USGS1953

Ground-water conditions in artesian aquifers in Brown County, Wisconsin

The principal water-bearing rocks underlying Brown County, Wis., are thick sandstone units of Cambrian and Ordovician age. Other aquifers include limestone and dolomite of Ordovician age, dolomite of Silurian age, and sands and gravel of Pleistocene and Recent age. Underlying the water-bearing formations are crystalline rocks of pre-Cambrian age which contain little or no water. Ground water is the source of all public and most private and industrial supplies in. the county. Several of the large industries use large quantities of surface water also. Most of the water is pumped from wells that penetrate the Cambrian sandstones where the water occurs under artesian conditions. From 1886, when the first deep well was drilled, to 1949, the pumpage in the county increased to an average of about 5 million gallons a day (mgd) in 1939 and to about 10 mgd in 1949. The piezometric level, which was about 100 feet above the land surface in 1886, was about 300 feet below the land surface in 1949. About 200 feet of this decline took place after 1938. The water-level-measurement program begun in 1946 shows that yearly fluctuations of water levels in observation wells range from less than 1 foot to about 90 feet, the fluctuations being larger at the center of the heavily pumped area. The highest water levels occur in the winter or spring and the lowest in the summer near the end of the season of maximum withdrawal. Coefficients of transmissibility and storage for the sandstones were obtained by making controlled pumping tests at Green Bay and De Pere. The coefficients were verified by comparing computed water-level declines and rates of withdrawal with actual ones. The computed values were within I0 percent of the actual values. Probable declines of water levels by 1960 were computed, using the same coefficients of transmissibility and storage, and assuming three different conditions of pumping. The additional decline in water level will be 15 to 150 feet in the center of the pumped area, depending upon the amount of increased pumping and its distribution relative to the present pumped area and to the recharge area. The water from the sandstones is a hard calcium magnesium bicarbonate water. Further work is needed to determine whether there is danger of contamination by salt water which occurs down the dip in the same formations. It is concluded that the rate of withdrawal from the area can be increased to 15 mgd by 1960 without dangerously lowering water levels, provided that new wells are properly spaced. In order to avoid expressive lowering of water levels, it is recommended that new wells be located west of Green Bay toward the recharge area. A detailed study has not been made of shallow aquifers in the county. Further work should be done to evaluate the possibilities of auxiliary supplies from the limestone of the Platteville formation or from the Niagara dolomite. Conservation should be practice.4 by all users of ground water to avoid waste resulting in lower water levels and higher pumping costs.

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