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Ground-water pumpage and water-level changes in the Milwaukee-Waukesha area, Wisconsin, 1950-61

Artesian water pressure in the deep sandstone aquifer continued to decline throughout most of the Milwaukee-Waukesha area, Wisconsin between 1950 and 1961. Areas of greatest water-level decline were in northeast Waukesha County and in northwest Milwaukee County. The chief cause of the decline was continued heavy pumpage. The major aquifers of southeastern Wisconsin are the Niagara aquifer, which is primarily Niagara Dolomite of Silurian age, and the sandstone aquifer, which consists of sandstones of Cambrian and Ordovician ages. Locally, the glacial sands and gravels ,of Pleistocene age also are important aquifers. In the Milwaukee-Waukesha area, the sandstone aquifer is completely artesian, confined above by the Maquoketa Shale. The Niagara aquifer is generally unconfined. Pumpage from the sandstone aquifer in the Milwaukee-Waukesha area de- creased from about 23.3 million gallons per day in 1950 to about 20.9 million gallons per day in 1961. The principal reason for decreased pumpage was sub- stitution of surface-water supply from Lake Michigan. Between 1950 and 1961, the water-level changes in wells in the sandstone aquifer ranged from plus 10 feet at Town of Lake to minus 98 feet in northwest Milwaukee. Except for a small area near Town of Lake, water levels in wells in the Milwaukee-Waukesha area were lower in 1961 than in 1950. Water-level changes were directly related to the pumpage pattern and pump- age changes. Increased pumpage at Waukesha and in northwest Milwaukee and continued heavy pumpage at Wauwatosa caused widespread water-level declines in northeast Waukesha County and in northwest Milwaukee County. Locally, decreased pumpage at West Milwaukee allowed limited recovery of water levels since 1957. Estimates of pumpage through the year 1975 indicate a pumpage decrease in the middle 1960's, followed by an increase in the late 1960's and early 1970's. Additional conversion to surface-water supply in Milwaukee County will account for most pumpage decreases. Increased pumpage is most likely in Waukesha County where the population is expanding rapidly and an adequate surface-water supply is not readily accessible. The westward shift of the pumpage pattern may cause an additional water-level decline of about 50 feet at Waukesha but will permit water levels to recover about 100 feet at West Allis by 1975. Partial or complete conversion to surface-water supplies by municipalities that depend entirely on water from the sandstone aquifer would allow greater use of the sandstone aquifer by isolated suburban developments and industries.

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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.

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Flow characteristics of Wisconsin streams: Flow-duration, Hhgh-flow, and low-flow tables for selected streams through water-year 1960

The collection of data on the flow of rivers in Wisconsin started on a continuing basis in 1913. A few streamflow records were started in the late 1800's, one as early as 1888 (Chippewa River at Chippewa Falls). Much of the work has been done under cooperative arrangements between the U.S. Geological Survey and various State and Federal agencies. These data have been published in the form of daily discharge tables, and monthly and yearly summaries.

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Water resources of the Green Bay area, Wisconsin

The Green Bay area comprises an area of about 525 square miles in eastern Wisconsin at the south end of Green Bay. It includes the western three-fourths of Brown County and the eastern one-ninth of Outagamie County. In 1960, the population of the area was estimated at 124,000. The most prominent topographic feature is the northwest-facing, southwestward trending Niagara escarpment. The area northwest of the escarpment drains into Green Bay via the Fox River, Suamico River, Duck Creek, and their tributaries. The area southeast of the escarpment is drained by streams that flow into Lake Michigan. The chief sources of surface water in the Green Bay area are the Fox River, Green Bay, and Lake Michigan. Smaller amounts of water are available from the East and Suamico Rivers and other streams. A sandstone aquifer is the principal source of the ground-water supply. The Niagara dolomite, although largely undeveloped, is potentially an important aquifer in the eastern part of the area. Small amounts of water are obtained also from the Platteville formation and from deposits of Pleistocene and Recent age. Water from the surfaceand ground-water sources is moderately hard to very hard. The Fox River, tributary to Lake Michigan at Green Bay, is a significant source of water for industrial use in the Green Bay area. The Menasha Dam, which controls release of water from the Lake Winnebago pool, is the major regulation on the Fox River, and it has considerable effect in reducing peak flows and supplementing low flows in the lower Fox River. The average discharge of the lower Fox River for the period 1898-1959, as measured at the gaging station at Rapide Croche Dam, was 2,687 mgd (million gallons per day). The longest consecutive period during which the discharge averaged less than 500 mgd was 80 days. The average discharge can be expected to fall below 700 mgd about once every 5 years for a 7-day period. In 1959, the average withdrawal of water from the Fox River was about 62 mgd. The water in the river is of the calcium magnesium bicarbonate type and is hard. The small streams in the area are utilized chiefly for stock watering; some of the water, however, is used for irrigation. The water in the small streams is more highly mineralized than the water in the Fox River and is very hard. Large quantities of water are available from Green Bay, but the disposal of industrial waste into the bay has restricted the use of the water. The major withdrawal is for condenser cooling, and, in 1959, it averaged about 415 mgd. The water from Green Bay is moderately hard but is of better chemical quality than the water from the Fox River and the small streams in the area. The only withdrawals of water from Lake Michigan for use in the Green Bay area are made by the city of Green Bay. In 1959, these withdrawals averaged 7.8 mgd. The lower Fox River is not subject to extremes of flow owing to the dampening effect of the Lake Winnebago pool and the regulation of flow at Menasha Dam. Cloudbursts over the lower Fox River valley below Menasha Dam, however, have occasionally caused extremely high water, as in 1922, when the discharge at the mouth of the Fox River was estimated to be about 50,000 mgd. Daily discharges greater than about 13,000 mgd occurred only 7 times in the period 1918-59. The 50-year flood of 15,500 mgd represents an average runoff of less than 2.6 mgd per square mile of drainage area, a relatively low runoff for a 50-year flood in Wisconsin. The sandstone aquifer is the principal source of ground water in the Green Bay area and furnishes water for public supply and industrial use. This aquifer includes rocks of Late Cambrian age, and the Prairie du Chien group and St. Peter sandstone of Ordovician age; it ranges in thickness from 550 to 640 feet. Ground water is found in openings along fractures and bedding planes and in the interstices between sand grains. The sandstone aquifer can support additional development of large supplies of ground water. Wells can be developed in most of the area that will yield 500 gpm (gallons per minute) or more, provided they are properly spaced and penetrate the entire thickness of the aquifer. It is estimated that the perennial yield of the sandstone in the Green Bay area could be at least 30 mgd if the aquifer is properly developed; only 5.4 mgd was withdrawn in 1959. The water from this sandstone aquifer is of the calcium magnesium bicarbonate type, is very hard, and, at a few places, contains objectionable amounts of iron. The Niagara dolomite, potentially a source of moderate to large quantities of water in the eastern part of the area, probably will yield 500 gpm or more to wells. In 1959, the average withdrawal of water for all uses was estimated at 495 mgd, of which 98.2 percent was from surface-water sources and 1.8 percent was from wells. About 485 mgd of water was withdrawn for industrial use, 6 mgd for public supply, and 4 mgd for rural use. The industrial use of water averaged 441 mgd for condenser cooling, 38 mgd fot processing by the paper industry, and 6 mgd for other industrial uses. The city of Green Bay used 7.8 mgd of water from Lake Michigan; other public supplies in the area used 2.6 mgd from wells. Of the withdrawals of water for rural use, about 75 percent was from wells and about 25 percent was from streams. The discharge of wastes into the lower Fox River and its tributary streams has altered the quality of the natural water. The wastes consist chiefly of treated municipal sewage and treated and untreated wastes from the paper industry, rendering plants, a sugar mill, and other industries. The industrial waste makes up about 90 percent of the oxygen-demand loading in the lower Fox River, and treated municipal sewage accounts for about 10 percent. The dissolved-oxygen concentration of water in the lower Fox River decreases rapidly in the vicinity of Green Bay during the summer when the river water is warm. If the periods when the river water is warmest, generally during July and early August, were to coincide with periods of lowest annual streamflow, generally in late August, the river would be unable to assimilate the loading of decomposable organic matter. In an emergency, industrial and public supply wells could supply at least 6 mgd for a sustained period and probably as much as 10 mgd for a period of several days. Six of the wells that formerly supplied the city of Green Bay are maintained in operating condition and could furnish about the same quantity of water as the industrial and other public supply wells. Small streams in the area would be supplemental sources of water, and the water in the Fox River and Green Bay is easily accessible.

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Geology and ground-water resources of Rock County, Wisconsin

Rock County is in south-central Wisconsin adjacent to the Illinois State line. The county has an area of about 723 square miles and had a population of about 113,000 in 1957 ; it is one of the leading agricultural and industrial counties in the State. The total annual precipitation averages about 32 inches, and the mean annual temperature is about 48 ? F. Land-surface altitudes are generally between 800 and 00 feet, but range from 731 feet, where the Rock River flows into Illinois, to above 1,080 feet, at several places in the northwestern part of the county. The northern part of Rock County consists of the hills and kettles of a terminal moraine which slopes southward to a flat, undissected outwash plain. The southeastern part of the county is an area of gentle slopes, whereas the southwestern part consists of steep-sided valleys and ridges. Rock County is within the drainage basin of the Rock River, which flows southward through the center of the county. The western and southwestern parts of ,the county are drained by the Sugar River und Coon Creek, both of which flow into the Pecatonica River in Illinois and thence into the Rock River. The southeastern part of the county is drained by Turtle Creek, which also flows into Illinois before joining the Rock River. Nearly all the lakes and ponds are in the northern one-third of the county, the area of most recent glaciation. The aquifers in Rock County are of sedimentary origin and include deeply buried sandstones, shales, and dolomites of the Upper Cambrian series. This series overlies crystalline rocks of Precambrian age and supplies water to all the cities and villages in the county. The St. Peter sandstone of Ordovician age underlies all Rock County except where the formation has been removed by erosion in the Rock and Sugar River valleys, and perhaps in Coon Creek valley. The St. Peter sandstone is the principal source of water for domestic, stock, and small industrial wells in the western half of the county. This sandstone also yields some water to uncased wells that tap the deeper rocks of the Upper Cambrian series. East of the Rock River the Platteville, Decorah, and Galena formations undifferentiated, or Platteville-Galena unit, is the principal source of water for domestic and stock wells. Unconsolidated deposits of glacial origin cover most of Rock County and supply water to many small wells. In the outwash deposits along the Rock River, wells of extremely high capacity have been developed for industrial and municipal use. The most significant feature of the bedrock surface in Rock County is the ancestral Rock River valley, which has been filled with glacial outwash to a depth of at least 396 feet below the present land surface. East of the buried valley the bedrock has a fiat, relatively undissected surface. West of the valley the bedrock surface is rugged and greatly dissected. Ground water in Rock County occurs under both water-table and artesian conditions; however, because of the interconnection and close relation of all ground water in the county, the entire system is considered to be a single groundwater body whose surface may be represented by one piezometric map. Recharge occurs locally, throughout the county. Nearly all recharge is derived directly from precipitation that percolates downward to become a part of the groundwater body. Natural movement of water in the consolidated water-bearing units is generally toward the buried Rock and Sugar River valleys. Movement of water in the sandstones of Cambrian age was calculated to be about 44 million gallons a day toward the Rock River. Discharge from wells in Rock County in 1957 was about 23 million gallons a day. Nearly 90 percent of this water was drawn from the area along the Rock River. Drilled wells, most of which were drilled by the cable-tool method, range in diameter from 3 to 26 inches, and in depth from 46 to 1,225 feet. Driven wells in alluvium and glacial drift are usually 1? to 2? in

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Ground-water conditions in the Green Bay area, Wisconsin, 1950-60

The Green Bay area, which includes parts of Brown, Outagamie, and Shawano Counties, has an area of about 525 square miles in eastern Wisconsin at the south end of Green Bay. In 1960, it had a population estimated at 124,000; Green Bay, the largest city in the area, had a population of 62,888. The Green Bay area is underlain by a basement complex of crystalline rocks of Precambrian age. Sedimentary rocks of Cambrian, Ordovician, and Silurian ages overlie the crystalline rocks. These rocks are divided, in ascending order, as follows: The Dresbach Group, Franconia Sandstone, and Trempealeau Formation of Cambrian age; the Prairie du Chien Group, St. Peter Sandstone, Platteville Formation, and Maquoketa Shale of Ordovician age; and the Niagara Dolomite of Silurian age. The Maquoketa Shale and Niagara Dolomite are present only in the eastern part of the area. Unconsolidated deposits, largely of Pleistocene age and glacial origin, overlie the older rocks in most of the area. The rocks of the Dresbach Group, Franconia Sandstone, Trempealeau Formation, Prairie du Chien Group, and St. Peter Sandstone are connected hydraulically and can be considered to form one aquifer, called the sandstone aquifer. The sandstone aquifer is the principal source of ground-water supply in the Green Bay area and is one of the most productive water-bearing units in Wisconsin. All the public water supplies in the area, except the supply for the city of Green Bay, and many of the industrial water supplies are obtained from wells tapping the sandstone aquifer. Rates of discharge of individual wells range from about 200 to 1,000 gallous per minute. The city of Green Bay also obtained its water supply from wells tapping the sandstone aquifer until August 1957, when it began using Lake Michigan as a source of water supply. Several industries also use large quantities of surface water. The Niagara Dolomite, although largely undeveloped, is potentially an important aquifer, in the eastern part of the area. Small amounts of water are obtained from dolomite of the Platteville Formation and from sand and gravel deposits of Pleistocene age. Recharge to the sandstone aquifer in the Green Bay area is derived chiefly from precipitation that infiltrates at or near the outcrop area of the aquifer in northwestern Brown County, eastern Outagamie and Shawano Counties, and southern Oconto County. The amount of recharge is estimated to be at least 30 mgd (million gallons per day). Withdrawals of water from wells tapping the sandstone aquifer in the area began when the first well was drilled in 1886. The withdrawals gradually increased to an average of about 6 mgd in 1940, about 10 mgd in 1950, and about 13 mgd in January-July of 1957, after which time the city of Green Bay discontinued pumping from wells. From August 1957 through 1960, average annual withdrawals of water remained relatively constant at about 5 mgd. Water levels in wells tapping the sandstone aquifer persistently declined until August 1957 as a result of the gradually increasing withdrawals of water. In the area of concentrated ground-water withdrawals in downtown Green Bay, the piezometric surface, which had been about 100 feet above land surface in 1886, was about 340 feet below land surface in 1957. The cessation of pumping by the city of Green Bay in August 1957 resulted in a decrease in withdrawals of ground water from about 13.1 mgd in the first half of 1957 to about 5.3 mgd in the last half and a rapid recovery in water levels. ]n the area of concentrated withdrawals, the piezometric surface had recovered about 300 feet by September 1960. Rises in water levels were recorded throughout the Green Bay area, with the amount of the rise depending on the distance from the Green Bay city wells. In September 1960, water levels appeared to be affected more by local variations in the rates of pumping than by the recovery resulting from 1957 reduction in pumping. Much additional ground water could

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Ground-water resources of Waupaca County, Wisconsin

Waupaca County is in east-central Wisconsin. No serious ground-water problems existed in 1960 except in a few localities where crystalline rock is near land surface or is covered by nearly impermeable till. The use of ground water for irrigation has not appreciably affected ground-water levels. The county is covered by Pleistocene till, glaciolacustrine (lake), glaciofluvial (stream), and eolian (wind) deposits. In the northern three-quarters of the county these deposits overlie Precambrian crystalline rocks; in the remainder, they overlie sandstone of Cambrian age and, to a minor extent, dolomite of the Prairie du Chien Group of Ordovician age. The deposits of Pleistocene age, particularly outwash, are the principal sources of ground water except in those areas where the saturated thickness is slight or the permeability low. The sandstone of Cambrian age is an important aquifer in the southeastern part of the county. The crystalline rocks of Precambrian age yield little water except from fractures, joints, and weathered zones, and they are a source of water only in areas where better aquifers are absent. Ground water in Waupaca County occurs under both water-table and artesian conditions. The source of this ground water is precipitation that falls on the county and percolates downward to the zone of saturation. Regional movement of ground water is to the Wolf River. In most of the county the direction of movement is eastward or southeastward, except in the southeastern corner of the county, where the movement is westward. Water-level fluctuations reflect the variations of ground-water storage or artesian pressure in response to variations in recharge and discharge. Declining water levels from 1956 to 1959 reflect a period of below-normal precipitation, and rising water levels in late 1959 and 1960 reflect above-normal precipitation. Average precipitation, runoff, and evapotranspiration in 1959 are estimated to be 1,000, 400, and 600 mgd (million gallons per day) respectively. Pumpage in the county was estimated to be about 4 mgd in 1959, and about half of this amount was used for public supplies. A pumping test of a well in outwash deposits near Waupaca indicated that at that point the coefficient of transmissibility is about 100,000 gpd (gallons per day) per ft, the permeability is about 1,000 gpd per sq ft, the coefficient of storage is about 0.2, and the specific capacity is 41 gpm (gallons per minute) per ft of drawdown. These hydraulic characteristics are probably in the same order of magnitude as the characteristics of outwash deposits in the county in general. The water from wells in Waupaca County, although hard and generally containing iron, is good for most purposes.

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Sediment characteristics of small streams in southern Wisconsin, 1954-59

The results of investigations of the sediment and water discharge characteristics of Black Earth Creek, Mount Vernon Creek, and Yellowstone River from 1954 to 1959 and Dell Creek for 1958 and 1959 indicate large differences in annual runoff and sediment yields. The suspended-sediment discharge of Black Earth Creek averaged 3,260 tons per year or 71 tons per square mile : the annual yields ranged from 27 to 102 tons per square mile. The annual suspended-sediment yield of Mount Vernon Creek ranged from 48 to 171 tons per square mile and averaged 96 tons per square mile. The maximum daily discharge was 1,120 tons on April 1, 1960, during a storm which produced 67 percent of the suspended load for that water year and exceeded the discharge for the preceding 3 years. The sediment discharge of the Yellowstone River averaged 6,870 tons per year or 236 tons per square riffle. The maximum daily sediment discharge, 3,750 tons on April 1, 1959, occurred during a 14-day period of high flow during which the sediment discharge was 15,480 tons. In 1958 and 1959, Dell Creek had suspended-sediment yields of 4.7 and 26 tons per square mile of drainage area. The suspended sediment transported by Black Earth and Mount Vernon Creeks is about two-thirds clay and one-third silt. For Yellowstone River the particle-size distribution of the suspended sediment ranged from three-fourths clay and one-fourth silt during periods of low sediment discharge to one-third clay and two-thirds silt during high sediment discharges. For Dell Creek nearly all of the suspended sediment is clay, but the bed load is sand. The mean sediment concentration of storm runoff averaged two to three times more in the summer than in the winter. No significant changes with time occurred in the relation between storm runoff and sediment yield.

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Hydrology of upper Black Earth Creek basin, Wisconsin, with a section on surface water

The upper Black Earth Creek drainage basin has an area of 46 square miles and is in Dane County in south-central Wisconsin. The oldest rock exposed in the valley walls is the sandstone of Late Cambrian age. Dolomite of the Prairie du Chien Group of Ordovician age overlies the sandstone and forms the. resistant cap on the hills. The St. Peter Sandstone, Platteville and Decorah Formations, and Galena Dolomite, all Ordovician in age, form a narrow belt along the southern boundary of the area. Outwash and alluvium of Pleistocene and Recent age fill the valleys. The eastern half of the area was glaciated and is covered with till. The sandstone of Late Cambrian age and the sand and gravel of the outwash deposits are hydraulically connected. Ground water occurs under unconfined (water-table) conditions in the western unglaciated part of the basin and under artesian conditions beneath the till locally in the eastern part. The source of most of the ground water is direct infiltration of precipitation; however, some ground water enters the area as underflow from the south. About 7 inches of the 30 inches of average annual precipitation recharges the ground-water reservoir. The ground water generally moves toward Black Earth Creek where it is discharged. Some ground water moves out of the basin as underflow beneath the valley of Black Earth Creek, and some is discharged by evapotranspiration or is withdrawn by pumping from wells. Water levels in shallow nonartesian wells respond rapidly to precipitation. The effect of precipitation on water levels in artesian wells is slower and more subdued. Water levels are generally highest in spring and lowest in fall and winter. The flow of upper Black Earth Creek is derived mostly from ground-water discharge, except during short periods of and immediately after precipitation when most of the flow is derived from surface runoff. The runoff from upper Black Earth Creek basin decreased from an average of 8.72 inches per square mile of drainage area in 1955 to 5.55 inches in 1958; the decrease reflects the generally decreasing precipitation and declining water levels in the basin during that period. On July 10, 1958, the discharge from the basin was 0.367 cubic feet per second per square mile, and the greatest discharge was 0.84 cubic feet per second per square mile from the southwest subbasin. The ground water has an average temperature of about 50°F. It is a calcium magnesium bicarbonate type water and is very hard.

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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.

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Floods in Wisconsin: Magnitude and frequency

Flood data from gaging stations on Wisconsin rivers and streams are listed in this report. From these data, composite frequency curves were defined which express the ratio of floods of various recurrence intervals to the mean annual flood. Multiple correlation techniques were used to obtain formulas that relate the basin parameters of drainage area, main channel slope, and lake and reservoir surface area to the mean annual flood. By combining the results from the mean annual flood formulas with the regional frequency curves, the flood-frequency relationship can be determined for most sites in the State where the drainage basin exceeds 20 square miles. The curves and formulas are not applicable to: main stem of several of the larger rivers, highly regulated streams where it is possible for man to alter flood peaks, and drainage basins under 70 square miles in a part of west-central Wisconsin.

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