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Hydrogeology of glacial deposits in a preglacial bedrock valley, Waukesha County, Wisconsin

This report describes the areal extent, thickness, and hydraulic properties of glacial deposits in a preglacial bedrock valley south of the city of Waukesha in southeastern Wisconsin. In the 40- square-mile study area, the preglacial bedrock valley underlies an area across which the Fox River flows. A previous regional study of the area indicated that extensive glacial sand and gravel deposits may exist in the preglacial bedrock valley. New test-hole, well-construction, and seismic data collected from 1986 through 1991 showed that the preglacial bedrock valley immediately south of the city of Waukesha is narrower and shallower than previously thought. However, these data indicate that thicknesses of saturated glacial deposits in excess of 250 feet exist in a 1- to 2-mile-wide part of the valley in the southern part of the study area. Test-hole logs indicate that clean sand and gravel deposits are present in a shallow part of the preglacial bedrock valley. Fifty to sixty feet of silty and clayey sand and gravel deposits appear to underlie varying thicknesses of relatively impermeable clay till in the center of the study area. Ground water flows from upland areas on the eastern and western sides of the Fox River and discharges to the Fox River and wetlands adjacent to the river. Results of a 6.5-hour aquifer test indicate that the silty sand and gravel deposits have an average transmissivity of about 140 feet squared per day and an average storage coefficient of about 1.2x10"3 at one location. The horizontal hydraulic conductivity of these deposits averages about 4 feet per day. Analysis of drawdown indicates that these deposits are part of a leaky confined-aquifer system and that some water is derived from storage in an overlying clay layer. The transmissivity value determined from this aquifer test and a lack of clean sand and gravel encountered in other test holes indicate that glacial deposits at these sites may not yield enough water for a large municipal water supply. Sand and gravel deposits, capable of development as a municipal supply, may be present in the southern part of the study area. However, additional test holes are needed to determine whether adequate sand and gravel deposits underlie this area.

Wisconsin↗

Sediment transport, particle size, and loads in North Fish Creek in Bayfield County, Wisconsin, water years 1990-91

North Fish Creek is underused as a trout and salmon hatchery despite its excellent water quality. The shifting-sand streambed in the lower 9 miles of the stream inhibits successful spawning and is a poor habitat for macroinvertebrates, the primary food for juvenile trout and salmon. To provide data necessary for evaluation of potential sand-loading-control practices, the U.S. Geological Survey determined total-sediment transport, particle size, and loads for three sites, designated A, B, and C, on North Fish Creek during water years 1990-91. At site C, the most upstream site, all sediment was transported as suspended sediment. The average annual total-sediment load during 1990- 91 was 479 tons. About 88 percent of the load was transported during periods of snowmelt or storm runoff. About 75 percent of the sediment load was silt- and clay-size particles; the remainder was sand. Total-sediment discharge was calculated by the modified-Einstein procedure to determine total sediment transport-rate relations for site A, the most downstream site, and for site B. Annual totalsediment load was 11,960 tons in water year 1990 and 18,430 tons in water year 1991 at site B. About 97 percent of the total load was transported during periods of snowmelt and storm runoff. About 60 percent of the total-sediment load was sand-size particles. Annual total-sediment loads were 20,690 tons and 33,100 tons in water years 1990 and 1991, respectively, at site A. About 67 percent of the total-sediment load was sand-size particles. Annual average streamflow, as indicated by flow in the Bois Brule River, was about 16 percent below average in water year 1990, and about 4 percent above average in water year 1991. There was little relation between watershed area and sediment loads for the three sites. The watershed of site C is about 41 percent of that of site A, but the sand load at site C was only 1 percent of that at site A. The watershed area between sites B and C is 40 percent of that above site A, but this area yielded 49 percent of the sand load at site A. Nineteen percent of the watershed above site A is between sites A and B, yet this area yielded about 50 percent of the sand load at site A.

Wisconsin↗

Hydrogeology of the sand and gravel aquifer in the vicinity of the Wild Rose State Fish Hatchery, north-central Waushara County, Wisconsin

The sand and gravel aquifer in the vicinity of the Wild Rose State Fish Hatchery is approximately 200 feet thick. The aquifer consists mostly of sand that was deposited as glacial till and outwash approximately 15,000 years ago. Hydraulic conductivity of the aquifer at the hatchery, calculated from slug tests, is approximately 18 feet per day. Ground water recharges west of the hatch ery, flows from northwest to southeast, and discharges to streams, lakes, springs, and flowing wells. Springs and flowing wells are common at the hatchery because of upward hydraulic gradients in the sand and gravel aquifer. Total flow from springs and wells at the hatchery is approximately 3 million gallons per day. The recharge area for the ground water discharging at the hatchery extends at least 5 miles to the west. Ground water may flow from or under the Pine River to wells and springs at the hatchery.

Wisconsin↗

Simulation of stage and hydrologic budget for Shell Lake, Washburn County, Wisconsin

A model that simulates lake stage was developed to test the current understanding of the hydrology of Shell Lake, Wisconsin and to provide a tool for predicting the effects of withdrawing lake water on future lake stages. The model code is written in Fortran and simulates daily lake stage by summing estimates of hydrologic-budget components - precipitation falling on the lake surface, water evaporating from the lake surface, runoff (consisting of overland flow to the lake and intermittent streams flowing into the lake), and ground-water flow out of the lake. The model was calibrated to intermittent lake stage measurements for the period 1948-98. The hydrologic budget model was coupled to UCODE, a parameter estimation model, to aid in estimating runoff coefficients. Trends in stage simulated by the calibrated model compare reasonably well with historical stage trends. The root mean square of the differences of simulated and measured daily lake stage for the period 1948-98 is 0.54 foot. Predictive simulations indicate that withdrawing lake water is an effective way of reducing lake stage. Several years of pumping for at least 200 days per year at rates of 1,000 to 2,000 gallons per minute would have been required to reduce 1990's high stages by about one foot.

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↗

Organochlorine and metal residues in eggs of waterfowl nesting on islands in Lake Michigan off Door County, Wisconsin, 1977-78

One egg from each of 114 red-breasted merganser (Mergus serrator) nests in 1977 and 92 nests in 1978 was collected and later analyzed for organochlorines, polybrominated biphenyls (PBBs), polychlorinated styrenes (PCSs). and metals. One egg was also collected from each of the dabbling duck nests located: Twenty-nine of these eggs were analyzed for organochlorines and metals in 1977; 10 eggs were analyzed in 1978. All merganser eggs contained DDE, polychlorinated biphenyls (PCBs), and dieldrin; all but one egg collected in 1978 contained DDT. DDE and PCB levels had declined since 1975 to a geometric mean of 7.4 ppm DDE and 20 ppm PCBs in 1977 and 7.6 ppm DDE and 19 ppm PCBs in 1978. Dieldrin residues in eggs had not declined from 1975 Ievels; the geometric mean was 0.78 ppm in 1977 and 0.76 ppm in 1978. Other organochlorines were present at low levels. Mercury residues averaged >0,50 ppm in merganser eggs and had not declined since 1975. Other metals were present at low levels. Dabbling ducks generally had much lower organochlorine and Hg residues than mergansers; DDE and PCBs were the only organochlorines present in the majority of eggs. Geometric means of PCBs and DDE in dabbling duck eggs did not exceed 2.0 ppm and 1.0 ppm, respectively. PBBs and PCSs were detected only in a few merganser eggs, at low levels. Eggshell thickness for red-breasted merganser eggs averaged 0.359 mm in 1977 and 0.355 mm in 1978, which is only 2%-3% below pre-1946 thicknesses. Mallard (Anas platyrhynchos) eggshell thicknesses averaged 0.331 mm in 1977 and 0.337 mm in 1978.

Pesticides Monitoring Journal↗

Base-flow study of Duck Creek basin Brown and Outagamie counties, Wisconsin

Streams in the Duck Creek basin gain ground water throughout most of their reaches, however, ground-water pumping of the Green Bay - DePere area may reduce the water being gained by the streams from ground water. The August 11, 12 measurements were made during base-flow period when flow duration was about 50 to 55 percent (table 2), The August 27 measurements were made during a lower base-flow period when flow duration was about 70 to 80 percent. About 80 percent duration is, more representative of low-flow conditions during the summer.

Wisconsin↗

Base-flow study of East River basin Brown and Calumet counties, Wisconsin

Streams in the East River basin gain ground water throughout most of their reaches, however, ground-water pumping of the Green Bay - DePere area may reduce the water being gained by the streams from ground water. The August 13, 14 measurements were made during base-flow period when flow duration was about 50 to 55 percent (table 2). The August 28 measurements were made during a lower base-flow period when flow duration was about 70 to 80 percent. About 80 percent duration is more representative of low-flow conditions during the summer.

Wisconsin↗

Base-flow study of Little Suamico River basin Oconto, Brown and Shawano counties, Wisconsin

The Little Suamico River is a gaining stream throughout its entire reach. No loss of water from the streams was noted between any measuring sites. The August 13 measurements were made during a base-flow period when flow duration was about 50 to 55 percent (table 2). The August 27, 28 measurements were made during a lower base-flow period when flow duration was about 70 to 80 percent. Flow duration at about 80 percent is more representative of low-flow conditions during the summer.

Wisconsin↗

Base-flow study of Suamico River basin, Oconto, Brown, Shawano and Outagamie counties, Wisconsin

The Suamico River is a gaining stream throughout its entire reach. No loss of water from the streams was noted between any measuring sites. The August 12 measurements were made during base-flow period when flow duration was about 50 to 55 percent (table 2). The August 28 measurements were made during a lower base-flow period when flow duration was about 70 to 80 percent. Flow duration at about 80 percent is more representative of low-flow conditions during the summer.

Wisconsin↗

Water resources of Racine and Kenosha Counties, southeastern Wisconsin

Urbanization and changes in regional development in Racine and Kenosha Counties are increasing the need for water-resources information useful for planning and management. The area is fortunate in having abundant supplies of generally good quality water available for present and projected future needs. Lake Michigan and ground-water reservoirs have great potential for increased development. Lake Michigan assures the urbanized area in the eastern part of the two counties of a nearly inexhaustible water supply. In 1967 the cities of Racine and Kenosha pumped an average of 32.6 mgd (million gallons per day) from the lake. Water from Lake Michigan is of the calcium magnesium bicarbonate type, but it is less hard than water from other sources. Discharge from Racine and Kenosha Counties into Lake Michigan is low and has little effect on the lake. The Root and Pike Rivers and a number of smaller streams contribute a mean flow of about 125 cfs (cubic feet per second) to the lake. Ground water, approximately 5 cfs, enters the lake as discharge from springs or as seeps. The Des Plaines, Root, and Pike Rivers drain areas of relatively impermeable silty clay that promotes rapid surface runoff and provides little sustained base flow. Sewage sometimes accounts for most of the base flow of the Root River. In contrast, the Fox River, which drains the western half of the area, has steady and dependable flow derived from the sand and gravel and the Niagara aquifers. Sewage-plant effluent released to the Fox River in 1964 was about 5 percent of the total flow. A 5-mile reach of the Root River loses about 30,000 gpd (gallons per day) per mile to the local ground-water reservoir and is a possible source of ground-water contamination. Thirty-five of the 43 lakes in the area are the visible parts of the groundwater table, and their stages fluctuate with changes in ground-water levels. The rest of the lakes are perched above the ground-water table. Flooding is a recurring but generally minor problem along occupied reaches of flood plains of all the streams. However, in 1960 a flood on the Fox River, which had a recurrence interval of 60 years, caused considerable damage near the village of Silver Lake. At the same time, a flood on the Root River, which had a recurrence interval of 100 years, caused damage in Racine. The sandstone aquifer, a major artesian reservoir underlying all of Racine and Kenosha Counties, is used as a water supply for industries, institutions, and three communities. Pumpage for these uses was about 3.3 mgd in 1967. The greatest decline of water levels, attributed to both local and regional pumping, was 7 feet per year at Burlington. The specific capacities of wells developed in the Mount Simon Sandstone are about 5 gpm (gallons per minute) per foot of drawdown; in the Galesville and Franconia Sandstones, about 4 gpm per foot of drawdown; and in the St. Peter Sandstone, about 1 gpm per foot of drawdown. Yields of more than 1,000 gpm are obtained from wells tapping the Galesville and Franconia Sandstones and penetrating large crevices in the Trempealeau Formation near Burlington and Union Grove. About 2.5 mgd of ground water in the sandstone aquifer was diverted from the two-county area toward the Milwaukee and Chicago pumping centers in 1963--about 1.7 mgd moving from Racine County toward Milwaukee and 0.8 mgd moving from Kenosha County toward Chicago. Recent regional waterlevel declines in the sandstone aquifer have ranged from about 3 to 5 feet per year. This decline in water levels represents a ground-water depletion of about 0.5 mgd; however, the aquifer is not being dewatered, nor are water levels declining in the recharge area. The sandstone aquifer receives about 80 percent of its recharge from its outcrop area west of the two counties. In 1963 about 3.5 mgd moved eastward laterally from the recharge zone in western Walworth County, and about 1 mgd leaked downward through the overly

Wisconsin↗

Using enteric pathogens to assess sources of fecal contamination in the Silurian Dolomite Aquifer: Preliminary results

The fractured Silurian dolomite aquifer is an important, but vulnerable, source of drinking water in northeast Wisconsin (Sherrill in Geology and ground water in Door County, Wisconsin, with emphasis on contamination potential in the Silurian dolomite, 1978; Bradbury and Muldoon in Hydrogeology and groundwater monitoring of fractured dolomite in the Upper Door Priority Watershed, Door County, Wisconsin, 1992; Muldoon and Bradbury in Assessing seasonal variations in recharge and water quality in the Silurian aquifer in areas with thicker soil cover. p 45, 2010). Areas underlain by the Silurian dolomite aquifer are extremely vulnerable to groundwater contamination from various land-use activities, especially the disposal of human wastewater and dairy manure. Currently there is no consensus as to which source of wastewater generates the greater impact to the aquifer.

Conference Paper↗

Hatchling emergence ecology of Ouachita map turtles (Graptemys ouachitensis) on the lower Wisconsin River, Wisconsin, USA

Despite its biological importance in shaping both individual fitness and population structure, much remains to be learned about the hatchling emergence ecology of most freshwater turtles. Here, we provide some of the first details on these early life stages for the Ouachita map turtle ( Graptemys ouachitensis ) obtained during 2015–2017 along the lower Wisconsin River, Iowa County, Wisconsin, and integrate our results into related research within the genus Graptemys . Dedicated trail cameras over in situ turtle nests provided otherwise difficult to obtain observational data relevant to natural hatchling emergence without disturbing nests or hatchlings. In contrast to some earlier reports for Graptemys , hatchling emergence was mostly diurnal and synchronous, primarily in the morning soon after soil temperatures began to rise from overnight low values. Data suggest a temperature change model of cueing hatchling emergence, which may represent a local or regional adaptation to reduce nocturnal predation risks, mostly from raccoons ( Procyon lotor ), or may simply reflect default diurnal hatchling activity patterns when not affected by thermal constraints. Aside from predation, hatchlings on this small study site are affected by vegetative shading, leading to relatively long times to first emergence periods (mean, 82.3 d), low mean nest temperatures (25.9°C), and a likely male-biased sex ratio. These findings highlight the value of hatchling emergence studies in revealing important influences on population viability and in guiding appropriate habitat management in conservation efforts.

Wisconsin↗

Lead and zinc deposits of the Beetown area, Wisconsin

The Beetown area, in Grant County, Wisconsin, in the Northwestern part of the Upper Mississippi Valley zinc-lead district, lies in the western part of T. 4 N., R. 4 W., and the eastern part of T. 4 N., R. 5 W. The village of Beetown is at about its center. Recent geologic investigations in the area by the U.S. Geological Survey, in cooperation with the Wisconsin Geological and Natural History Survey, indicate that further prospecting for both lead and zinc ore is justified. This brief preliminary paper discusses geologic features of the lead and the zinc deposits. It is one of several areas within the district chosen for detailed geologic study because surface indications and past production suggest that the area may contain undiscovered lead and zinc deposits. This report is based on field work that began in July 1947 and continued at intervals until September 1949.

Wisconsin↗

Summary of fish communities in Underwood Creek, Milwaukee, Wisconsin, April 2021

Portions of Underwood Creek in Milwaukee County, Wisconsin were reconstructed beginning in 2010 to allow for improved fish habitat and better management of streamflow during storm events. Four reaches of Underwood Creek were sampled in April 2021 for fish abundance by species to evaluate the status of fish communities after reconstruction efforts were completed. A total of 25 fish species were collected during the April 2021 sampling events. Reach D, a recently restored reach, contained the most fish species (14) and individuals (391). White suckers ( Catostomus commersonii ) were present in three of four reaches, fulfilling one of the success metrics outlined in the Underwood Creek restoration plan. Another success metric, collection of young of year northern pike ( Esox lucius ), was not met in this sampling event. However, spawning steelhead ( Oncorhynchus mykiss ) were observed in several reaches, indicating that reconstruction allowed for suitable habitat and passage for some migratory fish.

Wisconsin↗

Use of a watershed-modeling approach to assess hydrologic effects of urbanization, North Fork Pheasant Branch basin near Middleton, Wisconsin

The North Fork Pheasant Branch Basin in Dane County, Wisconsin is expected to undergo development. There are concerns that development will adversely affect water resources with increased flood peaks, increased runoff volumes, and increased pollutant loads. To provide a scientific basis for evaluating the hydrologic system response to development the Precipitation Runoff Modeling System (PRMS) was used to model the upper Pheasant Branch Creek watershed with an emphasis on the North Fork Basin. The upper Pheasant Branch Creek (18.3 mi2; 11,700 acres) Basin was represented with 21 Hydrologic Response Units (daily time step) and 50 flow planes (5-minute time steps). Precipitation data from the basin outlet streamflow-gaging station located at Highway 12 and temperature data from a nearby airport were used to drive the model. Continuous discharge records at three gaging stations were used for model calibration. To qualitatively assess model representation of small subbasins, periodic reconnaissance, often including a depth measurement, was made after precipitation to determine the occurrence of flow in ditches and channels from small subbasins. As a further effort to verify the model on a small subbasin scale, continuous-stage sensors (15-minute intervals) measured depth at the outlets of three small subbasins (500 to 1,200 acres). Average annual precipitation for the simulation period from 1993 to 1998 was 35.2 inches. The model simulations showed that, on average, 23.9 inches were intercepted by vegetation, or lost to evapotranspiration, 6.0 inches were infiltrated and moved to the regional ground-water system, and 4.8 inches contributed to the upper Pheasant Branch streamflow. The largest runoff event during the calibration interval was in July 1993 (746 ft3/sec; with a recurrence interval of approximately 25 years). Resulting recharge rates from the calibrated model were subsequently used as input into a ground-water-flow model. Average annual recharge varied spatially from 2.3 inches per year in the highly impervious commercial/industrial area to 9.7 inches per year in the undeveloped North Fork Basin with an average overall recharge rate of 8.1 inches per year. Two development scenarios were examined to assess changes in water-budget fluxes. In scenario A, when development was predominantly low-density residential with 5 to 10 percent commercial development along principal roadways, mean annual streamflow increased by 53 percent, overland flow increased by 84 percent, base flow decreased by 15 percent and annual recharge to the regional ground-water system was reduced by 10 percent. In development scenario B, the entire North Fork and intervening area basins contained 50 percent commercial and 50 percent medium density residential land use. Annual storm runoff increased by over 450 percent. The ground-water model for the Pheasant Branch that used the scenario B recharge rates simulated a lowered water table with zero base flow and that flow from Frederick Springs would be reduced 26 percent from present-day (1993?98) conditions.An additional example application of the model evaluated locations of flood detention ponds and potential recharge areas that may mitigate the changes in flood peaks and ground-water recharge resulting from urbanization. From February 1998 through July 1998, water-quality samples were collected by use of stage-activated automated samplers. Median suspended- sediment concentrations were similar between the North and South Fork Basins (194 and 242 mg/L, respectively); however, for other constituents, North Fork values were considerably higher: median phosphorus concentrations by 4 times (1.5 and 0.35 mg/L), median ammonia concentrations by 13 times (1.9 and 0.14 mg/L), and the phosphorus-to-sediment ratio by more than 6 times (21 and 3.1 mg/g).

Wisconsin↗