Geology topics

Research about Dane County, Wisconsin

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

At least 19 recordsLinked to original sources

USGS2023

Fall contributions of phosphorus and nitrogen in stormwater runoff through weekly street cleaning

This report describes a study that characterized reductions in total and dissolved forms of phosphorus and nitrogen in stormwater runoff through implementation of a municipal leaf collection and street cleaning program in two medium-density residential catchments in Madison, Wisconsin. One catchment was established as a control in which no effort was made to remove leaf litter and other organic detritus from streets. The second catchment served as the test catchment in which leaf litter was removed through a combination of biweekly leaf collection and weekly mechanical-broom street cleaning. Loads of total and dissolved phosphorus in the test catchment were reduced by 46 and 51 percent (probability less than 0.20), respectively, and total and dissolved nitrogen by 42 and 52 percent (probability less than 0.20), respectively, with an active leaf collection and street cleaning program compared to no program in the control catchment. Results from this study support an ongoing effort to characterize how various combinations of municipal leaf collection and street cleaning can affect nutrient loads in urban runoff.

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USGS2020

Assessment of restorative maintenance practices on the infiltration capacity of permeable pavement

Permeable pavement has the potential to be an effective tool in managing stormwater runoff through retention of sediment and other contaminants associated with urban development. The infiltration capacity of permeable pavement declines as more sediment is captured, thereby reducing its ability to treat runoff. Regular restorative maintenance practices can alleviate this issue and prolong the useful life and benefits of the system. Maintenance practices used to restore the infiltration capacity of permeable pavement were evaluated on three surfaces: Permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). Each of the three test plots received a similar volume of runoff and sediment load from an adjacent, impervious asphalt parking lot. Six different maintenance practices were evaluated over a four-year period: Hand-held pressure washer and vacuum, leaf blower and push broom, vacuum-assisted street cleaner, manual disturbance of PICP aggregate, pressure washing and vacuuming, and compressed air and vacuuming. Of the six practices tested, five were completed on PICP, four on PC, and two on PA. Nearly all forms of maintenance resulted in increased average surface infiltration rates. Increases ranged from 94% to 1703% for PICP, 5% to 169% for PC, and 16% to 40% for PA. Disruption of the aggregate between the joints of PICP, whether by simple hand tools or sophisticated machinery, resulted in significant (p ≤ 0.05) gains in infiltration capacity. Sediment penetrated into the solid matrix of the PC and PA, making maintenance practices using a high-pressure wash followed by high-suction vacuum the most effective for these permeable pavement types. In all instances, when the same maintenance practice was done on multiple surfaces, PICP showed the greatest recovery in infiltration capacity.

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USGS2019

Stormwater-quality performance of line permeable pavement systems

Three permeable pavements were evaluated for their ability to improve the quality of stormwater runoff over a 22-month period in Madison, Wisconsin. Using a lined system with no internal water storage, permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA) were able to significantly remove sediment and sediment-bound pollutant loads from runoff originating from an asphalt parking lot five times larger than the receiving permeable pavement area. Reductions in total suspended solids were similar for all three surfaces at approximately 60 percent. Clogging occurred after approximately one year, primarily due to winter sand application that led to high sediment load in spring runoff. Winter road salt application resulted in high chloride load that was initially attenuated in all three permeable pavements but later released during subsequent spring runoff events. Total phosphorus load was reduced by nearly 20 percent for PICP and PA, and 43 percent for PC. These values were likely tempered by the export of dissolved phosphorus observed in PICP and PA, but not PC. Average removal efficiencies for metals were 40, 42, and 49 percent in PA, PICP, and PC, respectively. A median pH of 10.2 in PC effluent could explain elevated removal efficiency of phosphorus and select metals in PC over PICP and PA (median = 7.5 and 7.8, respectfully) through enhanced precipitation. Elevated pH values in PC may also have led to higher removal efficiencies for select metals than PICP or PA. The environmental benefits as well as potential unintended consequences of stormwater practices like permeable pavement that utilize infiltration as a form of treatment warrant consideration in management of urban runoff.

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USGS2019

Evaluation of stormwater treatment vault with Coanda-effect screen for removal of solids and phosphorus in urban runoff

Catch basins commonly are used by cities as part of a stormwater management plan to remove sediment and associated contaminants from stormwater, keeping them in compliance with regulations. Recently, the city of Madison, Wisconsin modified traditional catch basins by incorporating a fine-mesh (1-mm) Coanda-effect screen into the design with the goal of increasing removal of sediment and organic matter from stormwater. The US Geological Survey (USGS), in cooperation with the City of Madison, installed a water-quality monitoring station at such a catch basin to quantify reductions in total suspended solids (TSS), volatile suspended solids (VSS), suspended sediment concentration (SSC), total phosphorus (TP), and dissolved phosphorus (DP) from urban stormwater before entering Lake Monona. A comparison of the cumulative load from 33 samples collected during the summers of 2016 and 2017 showed 23% and 45% reductions in TSS and SSC, respectively. A smaller reduction was observed for TP, 16%, whereas DP remained unchanged. Reported traditional catch basin sediment removal varies greatly, although typical removal rates are similar. Results from this study will help regulated municipalities determine whether the use of screened catch basins can help meet water-quality goals.

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USGS2016

The 2016 groundwater flow model for Dane County, Wisconsin

A new groundwater flow model for Dane County, Wisconsin, replaces an earlier model developed in the 1990s by the Wisconsin Geological and Natural History Survey (WGNHS) and the U.S. Geological Survey (USGS). This modeling study was conducted cooperatively by the WGNHS and the USGS with funding from the Capital Area Regional Planning Commission (CARPC). Although the overall conceptual model of the groundwater system remains largely unchanged, the incorporation of newly acquired high-quality datasets, recent research findings, and improved modeling and calibration techniques have led to the development of a more detailed and sophisticated model representation of the groundwater system. The new model is three-dimensional and transient, and conceptualizes the county’s hydrogeology as a 12-layer system including all major unlithified and bedrock hydrostratigraphic units and two high-conductivity horizontal fracture zones. Beginning from the surface down, the model represents the unlithified deposits as two distinct model layers (1 and 2). A single layer (3) simulates the Ordovician sandstone and dolomite of the Sinnipee, Ancell, and Prairie du Chien Groups. Sandstone of the Jordan Formation (layer 4) and silty dolostone of the St. Lawrence Formation (layer 5) each comprise separate model layers. The underlying glauconitic sandstone of the Tunnel City Group makes up three distinct layers: an upper aquifer (layer 6), a fracture feature (layer 7), and a lower aquifer (layer 8). The fracture layer represents a network of horizontal bedding-plane fractures that serve as a preferential pathway for groundwater flow. The model simulates the sandstone of the Wonewoc Formation as an upper aquifer (layer 9) with a bedding-plane fracture feature (layer 10) at its base. The Eau Claire aquitard (layer 11) includes shale beds within the upper portion of the Eau Claire Formation. This layer, along with overlying bedrock units, is mostly absent in the preglacially eroded valleys along the Yahara River valley and in northeastern Dane County. Layer 12 represents the Mount Simon sandstone as the lowermost model layer. It directly overlies the Precambrian crystalline basement rock, whose top surface forms the lower boundary of the model. The model uses the USGS MODFLOW-NWT finite-difference code, a standalone version of MODFLOW-2005 that incorporates the Newton (NWT) solver. MODFLOW-NWT improves the handling of unconfined conditions by smoothing the transition from wet to dry cells. The model explicitly simulates groundwater–surface-water interaction with streamflow routing and lake-level fluctuation. Model input included published and unpublished hydrogeologic data from recent estimates of aquifer hydraulic conductivities. A spatial groundwater recharge distribution was obtained from a recent GIS-based, soil-water-balance model for Dane County. Groundwater withdrawals from pumping were simulated for 572 wells across the entire model domain, which includes Dane County and portions of seven neighboring counties—Columbia, Dodge, Green, Iowa, Jefferson, Lafayette, and Rock. These wells withdrew an average of 60 million gallons per day (mgd) over the 5-year period from 2006 through 2010. Within Dane County, 385 wells were simulated with an average withdrawal rate of 52 mgd. Model calibration used the parameter estimation code PEST, and calibration targets included heads, stream and spring flows, lake levels, and borehole flows. Steady-state calibration focused on the period 2006 through 2010; the transient calibration focused on the 7-week drought period from late May through July 2012. This model represents a significant step forward from previous work because of its finer grid resolution, improved hydrostratigraphic discretization, transient capabilities, and more sophisticated representation of surface-water features and multi-aquifer wells. Potential applications of the model include evaluation of potential sites for and impacts of new high-capacity wells, development of wellhead protection plans, evaluating the effects of changing land use and climate on groundwater, and quantifying the relationships between groundwater and surface water.

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USGS2004

Hydrologic, ecologic, and geomorphic responses of Brewery Creek to construction of a residential subdivision, Dane County, Wisconsin, 1999-2002

The U.S. Geological Survey (USGS), in cooperation with the Dane County Land Conservation Department (LCD) and the Wisconsin Department of Natural Resources (DNR), investigated the instream effects from construction of a residential subdivision on Brewery Creek in Dane County, Wisconsin. The purpose of the investigation was to determine whether a variety of storm-runoff and erosion-control best-management practices (BMPs) would effectively control the overall sediment load, as well as minimize any hydrologic, ecologic, and geomorphic stresses to Brewery Creek. Stormwater volumes decreased 60 percent from the preconstruction phase to the land-disturbance phase and slightly increased (9 percent) from the land-disturbance phase to the home-construction phase. The stormwater volumes were applied to total solids and total suspended solids concentrations to compute a solids load for each contaminant. Total and suspended solids load indicated a similar trend from preconstruction to land-disturbance phases with decreases of 52 and 72 percent, respectively. Both total and suspended solids load continued to decrease in the transition from land-disturbance to home-construction phases, by 22 and 37 percent, respectively. However, because of variability in the data, statistically there was no change in the magnitude of difference between the upstream and downstream solids load from one phase of construction to the next at the 90-percent confidence level. Other physical, biological, and ecological surveys including macroinvertebrates, fish, habitat, and geomorphology were done on segments of Brewery Creek affected by the study area. Macroinvertebrate sampling results (Hilsenhoff Biotic Index value, or HBI), on Brewery Creek ranged from 'very good' to 'good' water-quality with no appreciable differences during any phase of construction activity. Results for fish-community composition, however, were within the 'poor' range (Index of Biotic Integrity value, or IBI) during each year of testing. A general absence of intolerant species, with the exception of brown trout, reflects the low IBI values. Habitat values did not change significantly from preconstruction to postconstruction phases. Although installation of a double-celled culvert in Brewery Creek most likely altered the width-to-depth ratio in that reach, the overall habitat rating remained 'fair'. Fluvial geomorphology classifications including channel cross sections, bed- and bank-erosion surveys, and pebble counts did not indicate that stream geomorphic characteristics were altered by home-construction activity in the study area. Increases in fine-grained sediment at various cross sections were attributed to instream erosion processes, such as bank slumping, rather than increases in sediment delivery from the nearby construction site.

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USGS2003

Effects of best-management practices in the Black Earth Creek Priority Watershed, Wisconsin, 1984-98

The Wisconsin Department of Natural Resources and the U.S. Geological Survey began a comprehensive, multidisciplinary evaluation-monitoring program in 1989 to assess the effectiveness of the Wisconsin Nonpoint Source Program. Hydrologic and water-quality data were collected at Brewery and Garfoot Creeks in 1984 and 1985 (pre-best-management practices (BMPs) period) and 1997 and 1998 (post-BMP period). In rural areas, best-management practices may include conservation tillage, contour strip-cropping, streambank protection, and various barnyard-runoff controls. Water-quality samples were collected during base flow and storms. At Brewery Creek, no statistically significant differences in the median base flow water-quality concentrations between the pre- and post-BMP periods. At Garfoot Creek, the median suspended-sediment concentration at base flow decreased by 41 percent between the pre- and post-BMP periods and the median ammonia nitrogen concentration decreased by 67 percent. Both of these differences were statistically significant at the 0.05 (probability) level. For both Brewery and Garfoot Creeks, the median storm loads for suspended sediment, total phosphorus, and ammonia nitrogen were compared statistically by means of the Wilcoxon rank-sum test. This test also was applied to regression residuals for differences between the pre- and post-BMP periods. For Garfoot Creek, only the median load for ammonia nitrogen shows a statistically significant difference between the pre-and post-BMP periods. None of the median storm loads for Brewery Creek were statistically significant at the 0.05 level. The decrease of the regression residuals between the pre- and post-BMP periods for ammonia nitrogen at Brewery Creek and for total phosphorus and ammonia nitrogen at Garfoot Creek all were statistically significant at the 0.05 level. These reductions between the pre- and post-BMP periods likely are results of the installed BMPs. The effectiveness of the BMPs on water quality are watershed specific. The effectiveness of the practice will depend on the type, number, and location of the BMPs implemented.

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USGS2002

Helping at a Henslow's Sparrow nest in Wisconsin

We document the first reported observation of helping at the nest of a Henslow's Sparrow ( Ammodramus henslowii ). Video surveillance recorded two unbanded adults (a presumed male and female) and one banded adult male feeding chicks. No intraspecific aggression among the adults was observed.

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USGS2002

Simulation of Fish, Mud, and Crystal Lakes and the shallow ground-water system, Dane County, Wisconsin

A new MODFLOW lake package (LAK3) that simulates ground-water/lake interaction was used in simulation of Fish, Mud and Crystal Lakes?three shallow seepage lakes located in northwestern Dane County, Wis. The simulations were done to help determine the cause of increasing lake stages and provide a tool to estimate the effect of pumping water from Fish lake on future lake stages. The ground-water-flow model was developed using a telescopic-mesh refinement of the Dane and southwestern Columbia Counties regional model previously developed by the U.S. Geological Survey and the Wisconsin Geological and Natural History Survey. The parameter estimation model, UCODE, was coupled to the steadystate ground-water model to automate and optimize the calibration procedure. The steady-state model was calibrated to measured ground-water levels, Spring Creek streamflow measured at Lodi, and Fish and Crystal Lake stages. The results of the steady-state model were used as initial conditions in a transient simulation beginning in 1966 and ending in 1998. Recharge based on annual baseflow in Black Earth Creek, runoff based on measured coefficients, and precipitation and evaporation from the lake surfaces, were varied during the transient simulation. Measured Fish Lake stage was matched to simulated stage to calibrate the transient model. Model results suggest that the increase in regional ground-water recharge resulted in increased ground-water flow to the lake, which in turn resulted in increased lake stages. Simulation results of withdrawal of water from Fish Lake at 500 gallons per minute, assuming 1990?98 climatic conditions, indicate that after 1 year of pumping the stage of Fish and Mud Lakes would be reduced more than 1 foot and the stage of Crystal Lake would be reduced by less than 0.2 foot. When pumping is stopped, the lake stages would recover to near pre-pumping levels within about 3 years. When pumping is extended to 5 years, Fish and Mud Lake stage would be reduced by a maximum of 3.8 feet and Crystal Lake stage is reduced a maximum of 0.8 feet. After 4 years of recovery, Fish and Mud Lake stages are within 0.9 foot of prepumping levels and Crystal Lake stage is within 0.7 foot.

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USGS2001

The effects of large-scale pumping and diversion on the water resources of Dane County, Wisconsin

Throughout many parts of the U.S., there is growing concern over the effects of rapid urban growth and development on water resources. Ground- water and surface-water systems (which comprise the hydrologic system) are linked in much of Wisconsin, and ground water can be utilized both for drinking water and as a source of water for sustaining lakes, streams, springs, and wetlands. Ground water is important for surface-water systems because it commonly has greater dissolved solids and more acid-neutraliz- ing capacity than surface water or precipitation. The supplies of ground water are finite, however, and, in many cases ground water used for one purpose cannot be used for another. Moreover, ground-water use and withdrawal patterns may not be easy to alter once established. Thus, urban and rural planners are faced with decisions that balance the need for ground- water withdrawals while maintaining the quantity and quality of ground water for sustaining surface-water resources. Science-based information on the ground-water system and the connections to surface-water systems provides valuable insight for such decisions.

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USGS2001

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).

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USGS2000

Simulation of the recharge area for Frederick Springs, Dane County, Wisconsin

The Pheasant Branch watershed in Dane County is expected to undergo development. There are concerns that this development will adversely affect water resources, including Frederick Springs, a large spring complex in the watershed. The spring's recharge area was delineated using a telescopic mesh refinement (TMR) model constructed from an existing regional-scale ground-water flow model, and further refined by adding nearby surface-water features, a refined recharge array based on a surface-water model, and increasing the vertical leakage between the deep aquifers. This TMR model was formally optimized using the parameter estimation code UCODE. The results of optimization demonstrated that the best fit to measured heads and fluxes was obtained by using a horizontal hydraulic conductivity two times that of the original regional model for layer 2 and 80 percent smaller for layer 3. This range of parameter values was formally considered using a stochastic Monte Carlo approach. Two-hundred model runs used uniformly distributed, randomly sampled, horizontal hydraulic conductivity values within the range given by the TMR optimized values and the previously constructed regional model. A probability distribution of particles captured by the spring, or a probabilistic capture zone' was calculated from the realistic Monte Carlo results (136 runs of 200). In addition to portions of the local surface watershed, the capture zone encompassed distant areas in the North Fork of the Pheasant Branch watershed and areas entirely outside of the Pheasant Branch - demonstrating that the ground-watershed and surface watershed do not coincide. Analysis of samples from the springs and a nearby municipal well identified large contrasts in chemistry, even for springs within 50 feet of one another. The differences were stable over time, were present in both ion and isotope analyses, and showed a distinct gradation from high nitrate, high calcium, Ordovician-carbonate dominated water in western spring vents to low nitrate, lower calcium, Cambrian-sandstone influenced water in eastern spring vents. The difference in chemistry was attributed to distinctive bedrock geology as demonstrated by overlaying the 50 percent probability capture zone over a bedrock geology map for the area. This finding gives additional confidence to the capture zone calculated by the ground-water flow model.

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USGS1999

Simulation of the effects of operating lakes Mendota, Monona, and Waubesa, south-central Wisconsin, as multipurpose reservoirs to maintain dry-weather flow

A digital reservoir routing model was used to simulate the operation of Lakes Mendota, Monona, and Waubesa, south-central Wisconsin for various levels of minimum release. Twenty-five years of record (1970?94) were used in model simulation. The amount of water available to maintain streamflow and lake levels during dry periods has declined because of extensive pumping of ground water for municipal use and diversion of the effluent around the lakes. The goal of the simulation was to determine whether using the lakes as multipurpose reservoirs to maintain flow during periods of low flow would appreciably lower the lake levels. The model results indicated that it would be possible to maintain a minimum flow of 36 cubic feet per second in all but the driest years simulated (1970, 1976, 1977, 1981, 1989, and 1991) without lowering the lake levels more than they have been lowered from 1970 to 1994 under current operating conditions. Maintaining minimum flow would require detailed computations to guide the operation of the dams during the year.

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USGS1999

Sources of phosphorus in stormwater and street dirt from two urban residential basins in Madison, Wisconsin, 1994-95

Eutrophication is a common problem for lakes in agricultural and urban areas, such as Lakes Wingra and Mendota in Madison, Wisconsin. This report describes a study to estimate the sources of phosphorus, a major contributor to eutrophication, to Lakes Wingra and Mendota from two small urban residential drainage basins. The Monroe Basin empties into Lake Wingra, and the Harper Basin into Lake Mendota. Phosphorus data were collected from streets, lawns, roofs, driveways, and parking lots (source areas) within these two basins and were used to estimate loads from each area. In addition to the samples collected from these source areas, flow-composite samples were collected at monitoring stations located at the watershed outfalls (storm sewers); discharge and rainfall also were measured. Resulting data were then used to calibrate the Source Loading and Management Model (SLAMM, version 6.3, copyright 1993, Pitt & Vorhees) for conditions in the city of Madison and determine within these basins which of the source areas are contributing the most phosphorus. Water volumes in the calibrated model were calculated to within 23 percent and 24 percent of those measured at the outfalls of each of the basins. These water volumes were applied to the suspended- solids and phosphorus concentrations that were used to calibrate SLAMM for suspended-solids and phosphorus loads. Suspended-solids loads were calculated to be within 4 percent and 17 percent, total-phosphorus loads within 24 percent and 28 percent, and dissolved-phosphorus loads within 9 percent and 10 percent of those measured at the storm-sewer outfall at the Monroe and Harper basins, respectively. Lawns and streets are the largest sources of total and dissolved phosphorus in the basins. Their combined contribution was approximately 80 percent, with lawns contributing more than the streets. Streets were the largest source of suspended solids. Street-dirt samples were collected using industrial vacuum equipment. Leaves in these samples were separated out and the remaining sediment was sieved into >250 mm, 250-63 mm, 63-25 mm, <25 mm size fractions and were analyzed for total phosphorus. Approximately 75 percent of the sediment mass resides in the >250 mm size fractions. Less than 5 percent of the mass can be found in the particle sizes less than 63 mm. The >250 mm size fraction also contributed nearly 50 percent of the total-phosphorus mass and the leaf fraction contributed an additional 30 percent. In each particle size, approximately 25 percent of the total-phosphorus mass is derived from leaves or other vegetation.

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USGS1999

Evaluation of the effectiveness of an urban stormwater treatment unit in Madison, Wisconsin, 1996-97

An urban stormwater treatment unit was tested as part of an ongoing program of urban nonpoint- pollution research in Madison, Wis. Flow measurements were made and water samples were collected at the inlet to, outlet from, and bypass around the treatment chamber of the device that was installed to collect the runoff from a city maintenance yard. About 90 percent of the runoff water from the 4.3-acre basin was treated by the unit. The remaining 10 percent bypassed the treatment chamber when the flow rate reached approximately 500 gallons per minute. A 24-percent difference between the estimated amount (405 kilograms) and the actual amount (536 kilograms) of retained material in the treatment chamber may be attributed to bedload material that the automatic samplers could not effectively collect. Assuming this, 8 percent of the total mass in the untreated runoff water was estimated as the unsampled bedload. On the basis of water-sample data collected over the course of the study, the suspended solids removal efficiency of treatment chamber was about 25 percent, and the efficiency of the unit as a whole was 21 percent. If the unsampled bedload material was accounted for, the treatment-chamber efficiency was 33 percent. About 19 percent of the total phosphorus was removed from the water that passed through the treatment chamber and 17 percent was removed by the unit as a whole. Total polycyclic aromatic hydrocarbon (PAH) loads were reduced about 39 percent by the treatment chamber and 34 percent by the unit as a whole; these were some of the most effectively removed constituents. Total metals were reduced about 20 to 30 percent by both the treatment chamber and the unit as a whole. In general, dissolved constituents were unaffected by the unit. The material retained in the treatment chamber had high concentrations of lead and PAH and may be subject to special disposal restrictions based on those concentrations and the presence of benzo(a)anthracene. The chemical makeup of the retained material in other similar stormwater treatment units will probably vary depending on the land use and activities in the drainage basin.

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USGS1996

Variation in the relation of rainfall to runoff from residential lawns in Madison, Wisconsin, July and August 1995

The quality of runoff from residential lawns is a concern for municipal stormwater management programs. Land-use based computer models are increasingly being used to assess the impact of lawn runoff on urban watersheds. To accurately model the runoff for residential lawns, the variation in the relation of rainfall to runoff from lawns must be understood. The study described in this report measures the runoff parameters from 20 residential lawns in Madison, Wisconsin, using a rainfall simulator. It was determined that the saturated hydraulic conductivity does not vary significantly within a single residential lawn, but does vary significantly from one lawn to another. This variation is recognized in the entire rainfall-runoff relation from one lawn to another. The age of a lawn, or the years since development and turf establishment, is used as a surrogate of several lawn and soil characteristics to describe the variability in lawn runoff volumes. Runoff volumes from newly developed lawns are significantly greater than runoff from older lawns. This is an important consideration when modeling runoff for new developments. For older lawns, the date since lawn establishment does not explain the variation in the rainfall-runoff relation. In order for simple land-use based computer models to adequately account for the volume of runoff from pervious landscapes, field data from individual lawns would be necessary. A more realistic, alternative method may be to consider a basin-scale analysis of runoff from pervious landscapes.

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USGS1993

Sources of pollutants in Wisconsin stormwater

Rainfall runoff samples were collected from streets, parking lots, roofs, driveways, and lawns. These five source areas are located in residential, commercial, and industrial land uses in Madison, Wisconsin. Solids, phosphorus, and heavy metals loads were determined for all the source areas using measured concentrations and runoff volumes estimated by the Source Load and Management Model. Source areas with relatively large contaminant loads were identified as critical source areas for each land use. Streets are critical source areas for most contaminants in all the land uses. Parking lots are critical in the commercial and industrial land uses. Lawns and driveways contribute large phosphorus loads in the residential land use. Roofs produce significant zinc loads in the commercial and industrial land uses. Identification of critical source areas could reduce the amount of area needing best-management practices in two areas of Madison, Wisconsin. Targeting best-management practices to 14% of the residential area and 40% of the industrial area could significantly reduce contaminant loads by up to 75%.

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USGS1993

Simulation of the effects of hypothetical residential development on water levels in Graber Pond, Middleton, Wisconsin

An investigation of the effects of hypothetical residential development in the Graber Pond watershed was done by the U.S. Geological Survey in cooperation with the city of Middleton. The investigation entailed evaluation of the existing (1989) water budget and water-level conditions for the pond and the water-level conditions expected to result from the hypothetical development that may occur by the year 2000. A water-budget model was calibrated to closely match water levels observed from July 18-August 31, 1989. Water input to the pond during this period was computed to be about 2.58 feet. Of this, about 25 percent (0.65 foot) was from direct rainfall on the pond surface, about 19 percent (0.50 foot) was from storm runoff, and about 55 percent (1.43 feet) was discharge from a nearby manufacturing plant. Simulation of the hypothetical development conditions in the watershed predicts that the average late-summer pond level may rise about 0.7 foot.

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