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USGS2007

Surficial Geologic Map of the West Franklin Quadrangle, Vanderburgh and Posey Counties, Indiana, and Henderson County, Kentucky

The valley of the Ohio River is filled with alluvium and outwash (unit Qal), which total 33-39 m thick under the land surface in the southeast part of the West Franklin quadrangle in Indiana, and 30.5-35 m thick under Diamond Island in the southwest corner of the quadrangle. The deposits are chiefly fine- to medium-grained, lithic quartzose sand, interbedded by lenses of clay, clayey silt, silt, coarse sand, granules, and gravel. Although grain size of the river alluvium varies widely, in general it fines upward-being gravelly sand to sandy gravel in the lower part, mainly sand in the middle part, and silty and clayey in the upper part (Holocene). The middle and lower parts probably accumulated during the Wisconsin Episode (late Pleistocene). The sandy middle part contains interbeds of clay, silt, and minor gravel. At the base is highly consolidated mud (silt and clay), sand, and gravel 2-10 m thick. This unit may be valley train that predates the Wisconsin Episode. Creek alluvium (unit Qa) is silt, clayey silt, and subordinate intercalated fine sand, granules, and pebbles; the coarser grains are generally concentrated in the basal 1-2 m of the deposit. Lenses and beds of clay are present locally. Fossil wood collected from an auger hole in the alluvial deposits of Little Creek, at depths of 10.6 m and 6.4 m, were dated 16,650?50 and 11,120?40 radiocarbon years, respectively. Probable lacustrine terrace silt and clay (Qlt), so-called slackwater-lake or backwater deposits, form deposits 12-22 m thick in the lowest reaches of tributary creeks to the Ohio River. The surfaces of the lacustrine deposits are terraces a few meters higher than the modern creek flood plains. Covering the bedrock upland is loess (Ql) 3-7.5 m thick, deposited about 18,000-12,000 years before present. Most surficial deposits in the quadrangle are probably no older than about 35,000 yrs. Lithologic logs, shear-wave velocities, and other cone penetrometer data are used to interpret depositional environments and geologic history of the alluvium and lacustrine deposits.

Scientific Investigations Map↗

USGS1953

Ground-water conditions in the Milwaukee-Waukesha area, Wisconsin

Three major aquifers underlie the Milwaukee-Waukesha area: sandstones of Cambrian and Ordovician age, Niagara dolomite of Silurian age, and sand and gravel deposits of Pleistocene age. The Maquoketa shale of Ordovician age acts as a more or less effective seal between the Pleistocene deposits and Niagara dolomite above and the sandstone aquifer below. Crystalline rocks of pre-Cambrian age form an impermeable basement complex below the Paleozoic sedimentary rocks. The Paleozoic strata dip east at 25 to 30 feet to the mile. There is no evidence that any of the faults and folds known or surmised to be present acts as a barrier to the movement of ground water. The bedrock surface underlying the Milwaukee-Waukesha area is formed by the Niagara dolomite except in northeastern Milwaukee County, where it is dolomite and shale of the Milwaukee formation of Devonian age, and in some of the preglacial valleys where the uppermost bedrock formation is the Maquoketa shale. Unconsolidated deposits of glacial drift cover the surface of the bedrock almost completely. Buried valleys in the bedrock surface contain as much as 150 feet of water-bearing sand and gravel deposits. These deposits, along with the Niagara dolomite, could be developed as sources of water supplemental to that of the sandstone aquifer. The Niagara dolomite is an important aquifer; it yields water from crevices and solution channels. The sandstone aquifer consists of the Galena dolomite, the Platteville limestone, and the St. Peter sandstone of Ordovician age, and the Eau Claire and Mount Simon sandstones of Cambrian age. The St. Peter and Mount Simon are the most productive formations but the others supply some water to wells. Static water levels in the shallow aquifers have not declined to any great extent except in downtown Milwaukee, where a 50-foot-deep cone of depression exists. Static water levels in the sandstone aquifer declined as much as 350 feet in the Milwaukee area from 1880 through 1950. Recharge to the two shallow aquifers occurs locally from precipitation within the area. The major recharge area of the sandstone aquifer lies about 25 miles west of Wauwatosa. Some ground water is recharged to the sandstone aquifer locally by leakage from the Niagara dolomite, mostly through deep uncased wells. Ground water is the source of six municipal supplies and many industrial and commercial supplies in the area. Pumpage from deep wells has increased from about 2.5 mgd in 1900 to about 25 mgd in 1949, of which 6.0 mgd was derived from the shallow aquifers. The total withdrawal from the shallow aquifers, including the 6.0 mgd from the deep wells, was about 19.5 mgd in 1949. Thus the total in 1949 was 38.5 mgd for the area as a whole. Coefficients of transmissibility and storage for the sandstone aquifer were obtained by means of controlled pumping tests at Wauwatosa, Waukesha, Greendale, Town of Lake, and Jefferson. The coefficients were used to calculate the amount of water recharged from the Niagara dolomite to the sandstone aquifer in the area. About 5.5 mgd of the 23 mgd pumped from deep wells in 1950 was supplied locally by leakage from the Niagara dolomite. The coefficients, with corrections for boundaries, were also applied to past records of pumpage to calculate the water-level decline in the sandstone aquifer at Wauwatosa from 1880 through 1950. The calculated decline was 317 feet, and the actual decline was 307 feet. The future water-level decline in the sandstone aquifer at Wauwatosa resulting from estimated future pumping conditions was computed. If the pumpage in the area as ?. whole increases from about 23 mgd in 1950 to about 28 mgd in 1960, the water levels at Wauwatosa will decline as much as 65 feet more by 1960. It is estimated that the available recharge to the sandstone aquifer underlying the Milwaukee-Waukesha area is approximately 60 mgd. It is recommended that new deep wells be located to the west toward the recharge area and that the shallow aquifers be used as auxiliary sources to void excessive lowering of water levels in the sandstone aquifers. Conservation should be practiced by all users of ground water to avoid waste resulting in lower water levels and higher pumping costs.

Wisconsin↗

USGS2010

Development of a macrophyte-based index of biotic integrity for Minnesota lakes

Traditional approaches for managing aquatic resources have often failed to account for effects of anthropogenic disturbances on biota that are not directly reflected by chemical and physical proxies of environmental condition. The index of biotic integrity (IBI) is a potentially effective assessment method to integrate ecological, functional, and structural aspects of aquatic systems. A macrophyte-based IBI was developed for Minnesota lakes to assess the ability of aquatic plant communities to indicate environmental condition. The index was developed using quantitative point intercept vegetation surveys for 97 lakes that represent a range of limnological and watershed characteristics. We followed an approach similar to that used in Wisconsin to develop the aquatic macrophyte community index (AMCI). Regional adaptation of the AMCI required the identification of species representative of macrophyte communities in Minnesota. Metrics and scaling methods were also substantially modified to produce a more empirically robust index. Regression analyses indicated that IBI scores reflected statewide differences in lake trophic state (R2 = 0.57, F = 130.3, df = 1, 95, p < 0.005), agricultural (R2 = 0.51, F = 83.0, df = 1, 79, p < 0.005), urban (R2 = 0.22, F = 23.0, df = 1, 79, p < 0.005), and forested land uses (R2 = 0.51, F = 84.7, df = 1, 79, p < 0.005), and county population density (R2 = 0.14, F = 16.6, df = 1, 95, p < 0.005). Variance partitioning analyses using multiple regression models indicated a unique response of the IBI to human-induced stress separate from a response to natural lake characteristics. The IBI was minimally affected by differences in sample point density as indicated by Monte Carlo analyses of reduced sampling effort. Our analysis indicates that a macrophyte IBI calibrated for Minnesota lakes could be useful for identifying differences in environmental condition attributed to human-induced stress gradients. ?? 2010 Elsevier Ltd.

Ecological Indicators↗

USGS1986

Estimating magnitude and frequency of floods for Wisconsin urban streams

Equations for estimating magnitude and frequency of floods for Wisconsin streams with drainage basins containing various amounts of existing or projected urban development were developed by flood-frequency and multiple-regression analyses. Multiple-regression techniques were used to develop equations for estimating flood frequencies at ungaged urban sites. The flood-frequency equations are based on data from 32 urban gaging stations, including 19 crest-stage gages and 13 rainfall-runoff gaging stations. Significant characteristics in the equations are drainage area and impervious area. Standard errors of estimate for the regression equations ranged from 32%-39%. Separate equations were developed for Milwaukee County. The USGS Distributed Routing Rainfall-Runoff Model-Version II was used to extend records by synthesis for the 13 rainfall-runoff urban stations. (Author 's abstract)

Wisconsin↗

USGS1987

Hydrogeology of the Salamanca area, Cattaraugus County, New York

The hydrogeology of a 132-sq mi area centered at Salamanca, NY, is summarized in five maps at 1:24,000 scale. The maps show locations of wells and test holes, surficial geology and geologic sections, water-table surface, soil permeability, and land use. The valley-fill aquifer in the Salamanca area serves approximately 7,000 people through two major distribution systems with an average daily pumpage of 1.2 million gal/day. The aquifer, composed of outwash sand and gravel, averages 60 ft in thickness and overlies as much as 200 ft of lacustrine silt and clay. The aquifer is recharged directly from precipitation and through seepage from streams. Average annual recharge to the aquifer from direct precipitation and infiltration of runoff from adjacent hillsides is estimated to be 13 inches or 0.6 million gal/day/sq mi. The glacial features in the Allegheny valley near Salamanca are associated with Illinoian and Wisconsin glaciations. Illinoian features consist of small, isolated exposures of outwash and till emplaced against the valley walls. Wisconsin features deposited during Altonian and Woodfordian Times of the Wisconsin consist mainly of end moraines and valley-train outwash. (USGS)

New York↗

USGS2016

High rates of detection of Clade 2.3.4.4 Highly Pathogenic Avian Influenza H5 viruses in wild birds in the Pacific Northwest during the winter of 2014-2015

In 2014, Clade 2.3.4.4 H5N8 highly pathogenic avian influenza (HPAI) viruses spread across the Republic of Korea and ultimately were reported in China, Japan, Russia and Europe. Mortality associated with a reassortant HPAI H5N2 virus was detected in poultry farms in Western Canada at the end of November. The same strain (with identical genetic structure) was then detected in free-living wild birds that had died prior to December 8 of unrelated causes in Whatcom County, Washington, USA in an area contiguous with the index Canadian location. A gyrfalcon (Falco rusticolus) that had hunted and fed on an American wigeon (Anas americana) on December 6 in the same area and died two days later, tested positive for the Eurasian origin HPAI H5N8. Subsequently, an Active Surveillance Program using hunter-harvest waterfowl in Washington and Oregon detected ten HPAI H5 viruses, of three different subtypes (four H5N2, three H5N8 and three H5N1) with 4 segments in common (HA, PB2, NP and MA). In addition, a mortality-based Passive Surveillance Program detected 18 HPAI (14 H5N2 and four H5N8) cases from Idaho, Kansas, Oregon, Minnesota, Montana, Washington and Wisconsin. Comparatively, mortality-based passive surveillance appears to be detecting these HPAI infections at a higher rate than active surveillance during the period following initial introduction into the US.

Avian Diseases↗

USGS2008

Flood of June 2008 in Southern Wisconsin

In June 2008, heavy rain caused severe flooding across southern Wisconsin. The floods were aggravated by saturated soils that persisted from unusually wet antecedent conditions from a combination of floods in August 2007, more than 100 inches of snow in winter 2007-08, and moist conditions in spring 2008. The flooding caused immediate evacuations and road closures and prolonged, extensive damages and losses associated with agriculture, businesses, housing, public health and human needs, and infrastructure and transportation. Record gage heights and streamflows occurred at 21 U.S. Geological Survey streamgages across southern Wisconsin from June 7 to June 21. Peak-gage-height data, peak-streamflow data, and flood probabilities are tabulated for 32 USGS streamgages in southern Wisconsin. Peak-gage-height and peak-streamflow data also are tabulated for three ungaged locations. Extensive flooding along the Baraboo River, Kickapoo River, Crawfish River, and Rock River caused particularly severe damages in nine communities and their surrounding areas: Reedsburg, Rock Springs, La Farge, Gays Mills, Milford, Jefferson, Fort Atkinson, Janesville, and Beloit. Flood-peak inundation maps and water-surface profiles were generated for the nine communities in a geographic information system by combining flood high-water marks with available 1-10-meter resolution digital-elevation-model data. The high-water marks used in the maps were a combination of those surveyed during the June flood by communities, counties, and Federal agencies and hundreds of additional marks surveyed in August by the USGS. The flood maps and profiles outline the extent and depth of flooding through the communities and are being used in ongoing (as of November 2008) flood response and recovery efforts by local, county, State, and Federal agencies.

Scientific Investigations Report↗

USGS2011

Bi-phasic trends in mercury concentrations in blood of Wisconsin common loons during 1992-2010

We assessed the ecological risk of mercury (Hg) in aquatic systems by monitoring common loon ( Gavia immer ) population dynamics and blood Hg concentrations. We report temporal trends in blood Hg concentrations based on 334 samples collected from adults recaptured in subsequent years (resampled 2–9 times) and from 421 blood samples of chicks collected at lakes resampled 2–8 times 1992–2010. Temporal trends were identified with generalized additive mixed effects models and mixed effects models to account for the potential lack of independence among observations from the same loon or same lake. Trend analyses indicated that Hg concentrations in the blood of Wisconsin loons declined over the period 1992–2000, and increased during 2002–2010, but not to the level observed in the early 1990s. The best fitting linear mixed effects model included separate trends for the two time periods. The estimated trend in Hg concentration among the adult loon population during 1992–2000 was −2.6% per year, and the estimated trend during 2002–2010 was +1.8% per year; chick blood Hg concentrations decreased −6.5% per year during 1992–2000, but increased 1.8% per year during 2002–2010. This bi-phasic pattern is similar to trends observed for concentrations of methylmercury and SO 4 in lake water of an intensely studied seepage lake (Little Rock Lake, Vilas County) within our study area. A cause-effect relationship between these independent trends is hypothesized.

Wisconsin↗

USGS1979

Hydrologic data for floods of July 1978 in Southeast Minnesota and Southwest Wisconsin

Intense storms of July 1978 caused floods of historical significance in southeast Minnesota and southwest Wisconsin. Local, State, and Federal officials need data and information to evaluate, coordinate, and manage programs concerned with floods and flood losses. Because of a need to document stream discharges, elevations, and sediment concentrations, current-meter and indirect measurements were made at 34 gaging stations during or immediately after the floods. This report summarizes some of the hydrologic data collected. Peak discharges of record occurred at 20 gaging stations. Frequency of peak discharge equaled or exceeded the 100-year recurrence interval at 11 stations. The Federal Benchmark gaging station on the North Fork Whitewater River was destroyed. Five people died as a result of the floods, and property damages were estimated to exceed $114 million. Thirty-three counties were officially declared disaster areas.

Minnesota, Wisconsin↗

USGS1992

Data on water quality, lake sediment, and lake-level fluctuation, St. Croix Indian Reservation, Wisconsin, 1981-87

This report is a compilation of data on surface- and ground-water quality, lake sediment, and lake-level fluctuation collected by the U.S. Geological Survey (USGS) during 1981- 87 on or near the St. Croix Indian Reservation. The purpose of this report is to provide baseline data on selected aspects of the water resources of the St. Croix Indian Reservation as a referenceby which future hydrologic changes can be discerned. The tribal lands are adjacent to Bashaw, BigRound, Big Sand, Clam, Gaslyn, Rice, and Sand Lakes and the Danbury Settlement along the St. Croix River. Water samples from each of these lakes and Bear Lake, which is not adjacent to tribal land, were analyzed for water-quality indicators. Lakelevel fluctuations also were measured for each lake except Big Round Lake. Grain-size and chemical analyses were done on lake-sediment samples from Bashaw, Rice, Clam, Gaslyn, and Bear Lakes. Ground-water samples from wells on or near tribal land in Burnett County (27 wells) and Polk County (3 wells) were collected and analyzed for water quality.

Wisconsin↗

USGS1955

Sequence of alluviation along the Loup rivers, Valley County area, Nebraska

Alluviation along the North and Middle Loup rivers in Valley County, Nebraska, produced a series of alluvial silt beds on which are developed five interstadial soils of Brady (?), Cary and Mankato (?), Mankato (?), early Recent and late Recent age. No deposits of Illinoian age were found and in at least one place the Brady (?) soil is superposed on a gleyed horizon developed on the Sappa formation, which overlies the Grand Island formation. Post-Yarmouth erosion removed the Sappa formation and part of the Grand Island formation at most places. The characteristic Sangamon soil was not developed on uneroded remnants of the soil of Yarmouth age because of a wet, poorly drained environment. A large collection of molluscs obtained from this gley soil supports stratigraphic evidence indicating a Yarmouth age. Alluviation during the glacial substages of Wisconsin time and soil formation during the interglacial substages were uninterrupted by erosion until after development of the soil of Mankato age. The Wisconsin deposits were dissected to below the Brady soil in places, and the resulting gullies were filled with later alluvium. The late Recent fill terrace lies 15 feet below the top of the late Wisconsin terrace. Subsequent cutting and filling in late Recent time produced another terrace 11 feet below the older terrace. The modern gully was cut during the last century.

Nebraska↗

USGS2005

Impacts of petroleum production on ground and surface waters: Results from the Osage-Skiatook Petroleum Environmental Research A site, Osage County Oklahoma

Kharaka has been a research hydrogeochemist with the U.S. Geological Survey since1975. His current research covers the fields of water-rock-gas interactions, CO 2 sequestration, contamination from agricultural drainage and petroleum produced water, and fluid-fault interactions. Kharaka has authored more than 100 scientific papers and book chapters and has delivered about 200 presentations. He received his Ph.D. from the University of California, Berkeley, in 1971. Thordsen is a geologist, employed with the U.S. Geological Survey since 1981 and presently working in the project team Hydrogeochemistry of Fine Grained Sediments, in the Water Resources Division, National Research Program. His recent research covers water-rock interactions and geochemical modeling in geothermal systems, fault-fluid systems, and petroleum produced water brine impacts. He received his M.S. in geology from the Ohio State University in 1988. Kakouros has been a hydrogeologist in the U.S. Geological Survey Water Resources Division in Menlo Park, California, since 1999. His current research covers the fields of Se contamination from agricultural drainage, CO 2 sequestration, and contamination from petroleum and petroleum-produced water. Kakouros received his M.Sc. from the San Jose State University in 2001. Herkelrath is a physicist in the U.S. Geological Survey's Water Resources Division National Research Program in Menlo Park, California. Herkelrath received his Ph.D. in physics from the University of Wisconsin at Madison. His recent research interests include multiphase flow and solute transport modeling in shallow ground-water systems where oil or brine is present.

Oklahoma↗

USGS1976

Water resources of the Rock River watershed, southwestern Minnesota

This Hydrologic Atlas is one of series describing the 39 watershed units in Minnesota. The 1,750 sq mi in the Rock River watershed are glaciated upland plain including all of Rock County and parts of Pipestone, Murray, Lincoln, Nobles and Jackson Counties. The average annual water budget shows 25.8 inches precipitation, 3.1 inches surface runoff and 22.7 inches evapotranspiration. Water use in million gallons for 1970 was 3 ,333 ground water and 274 surface water. Domestic supplies accounted for 37 percent livestock 37 percent, and industrial 26 percent of total use. All 18 municipalities use ground water, mostly from glacial drift, seven use water from Precambrian aquifers. Precipitation recharges ground water through glacial deposits. Water-table and potentiometric maps and section show ground-water movement. Highest streamflow results from snowmelt and spring rains followed by recession in flow through summer, fall, and winter. Surface water and ground water are both very hard. Surface water and water from surficial and shallow drift aquifers generally range from 450 to 1,000 mg/liter dissolved-solids concentrations. Water from deep drift and from bedrock generally exceeds 1,000 mg/liter dissolved-solids concentration except where Precambiian quartzite aquifers underlie pre-Wisconsin drift. (Woodard-USGS)

Minnesota↗

USGS1997

Delineation of flooding within the upper Mississippi River Basin — Flood of July 10 and 27, 1993, in Kansas City Missouri, and Kansas City, Kansas, and vicinity

During spring and summer 1993, record flooding inundated many of the stream and river valleys in the upper Mississippi and the Missouri River Basins. The flooding was the result of widespread and numerous intense thunderstorms that, together with saturated soils, produced large volumes of runoff. The magnitude of flooding exceeded the 100-year discharge values (1-percent chance of exceedance in any given year) at many streamflow-gaging stations in Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, and Wisconsin. The flooding was unusual because of its long duration and widespread severe damage. The Mississippi and the Missouri Rivers were above flood stage for more than 1 month at several locations along their lengths. Millions of acres of agricultural and urban lands were inundated for weeks, and unofficial damage estimates exceeded $10 billion in the flooded States (Parrett and others, 1993), During summer 1993, large parts of Kansas City, Missouri, and Kansas City, Kansas, and vicinity were flooded from overflows of the Missouri and the Kansas Rivers and numerous smaller tributaries, This report provides flood-peak elevation data and delineates the arcalcktent of the 1993 floods in the Kansas City metropolitan area for July 10 and 27, 1993 (fig. 1A, sheet 1: B, sheet 2: C, sheet 3). The 1993 flood elevations and extent of flooding are compared with flood-plain boundaries defined by Flood Insurance Studies conducted by the Federal Emergency Management Agency (FEMA) for cities and counties in the area (U.S. Department of Housing and Urban Development, 1975–95). This report is one of a series of U.S. Geological Survey (USGS) investigations that document the effects of the 1993 flooding of the upper Mississippi and the Missouri River Basins and that improve the technical base from which flood-plain management decisions can be made by other agencies.

Kansas, Missouri↗

USGS1956

Geology and ore deposits of the Chicago Creek area, Clear Creek County, Colorado

The Chicago Creek area, Clear Creek County, Colo., forms part of the Front Range mineral belt, which is a northeast-trending belt of coextensive porphyry intrusive rocks and hydrothermal veins of Tertiary age. More than $4.5 million worth of gold, silver, copper, lead, zinc, and uranium was produced from the mines in the area between 1859 and 1954. This investigation was made by the Geological survey on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission. The bedrock in the area is Precambrian and consists of igneous rocks, some of which have been metamorphosed , and metasedimentary rocks. The metasedimentary rocks include biotite-quartz-plagioclase gneiss that is locally garnetiferous, sillimanitic biotite-quartz gneiss, amphibolite, and lime-silicate gneiss. Rocks that may be metasedimentary or meta-igneous are quartz monzonite gneiss and granite gneiss and pegmatite. The granite gneiss and pegmatite locally form a migmatite with the biotitic metasedimentary rocks. These older rocks have been intruded by granodiorite, quartz, and granite pegmatite. During Tertiary time the Precambrian rocks were invaded by dikes and plugs of quartz monzonite porphyry, alaskite porphyry, granite porphyry, monzonite porphyry, bostonite and garnetiferous bostonite porphyry, quartz bostonite porphyry, trachytic granite porphyry, and biotite-quartz latite-porphyry. Solifluction debris of Wisconsin age forms sheets filling some of the high basins, covering some of the steep slopes, and filling parts of some of the valleys; talus and talus slides of Wisconsin age rest of or are mixed with solifluction debris in some of the high basins. Recent and/or Pleistocene alluvium is present along valley flats of the larger streams and gulches. Two periods of Precambrian folding can be recognized in the area. The older folding crumpled the metasedimentary rocks into a series of upright and overturned north-northeast plunging anticlines and synclines. Quartz monzonite gneiss, granite gneiss and pegmatite, granodiorite, and quartz diorite and associated hornblendite are metamorphosed during this period. The second period of folding appears to have been the reflection at depth of faulting nearer the surface; it resulted in crushing as well as some folding of the already folded rocks into terrace and monoclinal folds that plunge gently east-northeast. The biotite-muscovite granite, which is the youngest major Precambrian rock unit, is both concordant (phacolithic) and crosscutting along the older fold system and has been fractured by the younger fold system.

Colorado↗

USGS1995

Radon-222 concentrations in ground water and soil gas on Indian reservations in Wisconsin

The weighted average radon-222 concentration of indoor air in homes located on Wisconsin Indian Reservations is 5.8 picocuries per liter, which exceeds the U.S. Environmental Protection Agency action limit of 4 picocuries per liter. Ground water is the principle source of drinking water on Wisconsin Indian Reservations and generally accounts for about 5 percent of the total indoor air radon-222 concentrations found in homes. To determine the distribution of radon-222, ground water from 29 private and community Wisconsin Indian Reservation wells and soil gas at a depth of about 3 feet below land surface adjacent to the wells were sampled. Sites with wells were distributed among the 11 Wisconsin Indian Reservations so that each Reservation contained at least 2 sites. The remaining seven sites were divided among the Reservation by acreage held by each tribe. Ground-water samples were collected using a syringe technique after the wells had been purged sufficiently to reach chemical stability. Samples were then sent by overnight mail to the U.S. Geological Survey, National Water Quality Lab for analysis by liquid scintillation counting. Soil gas was collected in Lucas cells, using a small-diameter soil probe and peristaltic pump. The cells were then analyzed by Lucas cell alpha scintillation counting with a portable radon detector. The highest radon-222 concentrations in ground water and soil gas are from sites with wells finished in the crystalline bedrock aquifer. Radon-222 concentrations in 29 ground-water samples collected from the sand and gravel and sedimentary and crystalline bedrock aquifers range from 260 to 22,000 picocuries per liter with a median concentration of 560 picocuries per liter. Only 2 of the 29 ground-water samples have radon-222 concentrations less than the U.S. Environmental Protection Agency proposed standard of 300 picocuries per liter. The highest radon-222 concentrations were found in ground water from wells in Shawano, Menominee, Forest, and Marathon counties. Radon-222 concentrations in soil gas range from 130 to 7,810 picocuries per liter with a median concentration of 560 picocuries per liter. For sites with wells finished in the sand and gravel aquifer, the coefficient of determination (R2) of the regression of concentration of radon-222 in ground water as a function of well depth is 0.003 and the significance level is 0.32, which indicates that there is not a statistically significant relation between radon-222 concentrations in ground water and well depth. The coefficient of determination of the regression of radon-222 in ground water and soil gas is 0.19 and the root mean square error of the regression line is 271 picocuries per liter. Even though the significance level (0.036) indicates a statistical relation, the root mean square error of the regression is so large that the regression equation would not give reliable predictions. Because of an inadequate number of samples, similar statistical analyses could not be performed for sites with wells finished in the crystalline and sedimentary bedrock aquifers.

Wisconsin↗

USGS1966

Geology of the Cerro Summit quadrangle, Montrose County, Colorado

The Cerro Summit quadrangle covers 58 square miles of dissected plateau on the south flank of the Gunnison uplift in southwestern Colorado. It lies east of the Uncompahgre River valley and south of the Black Canyon of the Gunnison River. Rocks dip gently in most of the quadrangle, but they are locally upturned and faulted on the margin of the Gunnison uplift and are intensely deformed in the core of the uplift. The rocks exposed are of Precambrian, late Mesozoic, and Cenozoic age. Precambrian rocks include metasedimentary schist and gneiss, granitic pegmatite, and olivine gabbro. The oldest Mesozoic rocks exposed are continental, fresh-water, and lagoonal deposits in the Late Jurassic Entrada Sandstone, Wanakah Formation, and Morrison Formation. Channel-fill deposits that unconformably overlie the Jurassic rocks are possibly the Burro Canyon Formation of Early Cretaceous age. Upper Cretaceous rocks include marine and nearshore deposits of the Dakota Sandstone, Mancos Shale, and Pictured Cliffs Sandstone, and the fresh- and brackish-water sandstone, shale, and coal of the Fruitland Formation. Rocks of Late Cretaceous age that crop out in the adjacent Cimarron Ridge area may also have been deposited in this quadrangle but are now eroded; these rocks include the nonmarine Kirtland Shale and an unnamed volcanic conglomerate and tuff breccia. Nine faunal zones in the Mancos Shale help to establish the correct correlation of units in the Upper Cretaceous. The Pictured Cliffs Sandstone, Fruitland Formation, and Kirtland Shale of the Cerro Summit area have been mapped by some geologists as the Mesaverde Formation. Fossils indicate that the rocks are younger than the type Mesaverde. The unnamed volcanic rocks represent major volcanism in nearby areas. A Late Cretaceous (Maestrichtian) age for the volcanism is indicated by palynological evidence and an isotopic age of approximately 66 million years. Middle Tertiary rocks are conglomerate and tuff breccia. Upper Tertiary or lower Quaternary rocks include gravel along Pool Gulch and older landslide debris on Waterdog Peak. Pleistocene and Recent deposits consist of the older stream gravel of Shinn Park, valley-fill deposits of Bostwick-Shinn Park, and pediment, landslide, eolian, alluvial, and colluvial deposits. P1elstocene valley-fill deposits of Bostwick-Shinn Park were deposited during the Cedar Ridge, or Kansan, to Pinedale or late Wisconsin times. The valley-fill deposits are divided into five units that are separated by strong Interglacial or Interstadial soils and that contain three volcanic ash beds. Chemical and petrographic data suggest that the middle ash bed may correlate with the Pearlette Ash Member (late Kansan) of the Sappa Formation in Nebraska. Alluvium on two pediment surfaces seems to be of Sacagawea Ridge or Illinoian age. Landslide deposits, of Pleistocene and Recent age, cover about 85 percent of the quadrangle; most of the deposits were formerly mapped as till. The name Cerro Till was abandoned because till does not occur in the type area. The dominant tectonic structures are the high-angle Cimarron fault of a few thousand feet displacement and the broad Montrose syncline. Evidence in the Cimarron Ridge area suggests that these structures formed in Late Cretaceous (Maestrichtian) time. Much of the strata near the surface of the quadrangle has been involved in landsliding that has continued from late Tertiary to the present.

Open-File Report↗

USGS1992

Applying the DRASTIC model: A review of county-scale maps

The potential for contamination of ground water has become an issue of great concern to citizens and government alike, especially in the last decade. Numerous methods for assessing ground water vulnerability to contamination have been proposed and used. These methods include field-scale deterministic models that predict the rate of migration and fate of specific chemicals, and regional models that attempt to show general trends of ground-water vulnerability to contamination. To address regional ground-water vulnerability, a model may focus on characteristics of the soil, the geologic materials at and above the unconfined water table, or on the larger part of the geologic framework containing aquifers. A model's focus significantly affects the characteristics and, therefore, the utility of maps produced by the model. For example, a model focusing on the soil or vadose zone cannot adequately characterize the contamination potential of confined aquifers. The most commonly-used method for regional assessment of ground-water vulnerability is called "DRASTIC," an acronym for the seven factors that comprise the model. The U.S. Environmental Protection Agency (EPA) funded the development of the DRASTIC model, and used it as an assessment tool in their National Pesticide Survey (USEPA, 1992). In that Survey and in other assessments of contamination potential from application of agricultural chemicals, the pesticide version of DRASTIC is used; it differs from the standard DRASTIC model only in the degree of weighting applied to the seven factors. The DRASTIC model was developed by a committee of technical advisors who used the consensus approach to specify the relative significance of each factor. DRASTIC was designed primarily as a regional tool for prioritization, or screening, to indicate those areas (of at least 100 acres in size) which are generally more sensitive to contamination and, therefore, in need of more detailed mapping and evaluation or monitoring. The committee also intended DRASTIC to support decisions on allocation of scarce monitoring or remediation resources, and to serve as an educational tool. A detailed user's manual for the DRASTIC model (Aller and others, 1987) provides descriptions of common hydrogeologic settings across the United States and expected values for the seven factors; with this information and a specified "weight" or multiplier applied to each factor, DRASTIC scores can be calculated for each setting, and a map of these DRASTIC scores generated. The authors of this model intended it to be sufficiently objective and straightforward that it could be effectively used by persons with but a rudimentary knowledge of hydrogeologic principles. By adjusting the factor values for actual or interpreted local conditions a more knowledgeable person should be able to produce a somewhat more realistic and, therefore, reliable map of ground water vulnerability than by using the expected values for a given hydrogeologic setting. Other models for evaluating regional ground-water vulnerability have been developed; of importance to this report are models developed by the Illinois State Geological Survey (ISGS), the Wisconsin Department of Natural Resources (WDNR), and a joint effort between the U.S. Geological Survey (USGS) and the ISGS. All of these models, as well as DRASTIC, can only estimate the relative potential for contamination, either with a numerical scheme or a hierarchy of contamination potential map units. The model developed by WDNR (Schmidt, 1987) is based on a numerical scheme. It was used to generate a statewide contamination susceptibility map of Wisconsin (Schmidt and Kessler, 1987); Schmidt (1987) defines ground water contamination susceptibility as the "ease with which water (and, presumably, accompanying contaminants) at the surface can reach the water table." The model is not limited to aquifers, but rather considers all unconfined ground water whether in sandy surface aquifers or low-permeability glacial till. Ground water in confined aquifers is not addressed. Contamination susceptibility is estimated by a factor-weighting scheme similar in concept to DRASTIC. The factors (soil texture, surficial deposits, depth to the water table, bedrock type, and glacial drift thickness) are assigned an arbitrary value based on perceived importance. These numbers are then weighted and summed to produce the contamination susceptibility score. This model is compared and contrasted with other models elsewhere in this report. In contrast, the ISGS method avoids the use of a numerical system to rate the relative potential for contamination, and instead orders the map units in a hierarchy from relatively low to relatively high contamination potential. Also in contrast to the two models described above, the ISGS model relies solely on the textural character of the geologic framework to a specified depth. For example, a statewide map (Berg and others, 1984, scale 1:500,000) addresses land burial of wastes, and shows the contamination potential of aquifers within geologic units in the upper 50 feet. Another ISGS map (Keefer and Berg, 1990) addresses the contamination of major, economically important aquifers, and therefore evaluates contamination potential to greater depths (to greater than 300 feet). In general, the ISGS contamination potential maps evaluate aquifers, and do not evaluate potential for contamination of ground water at the unconfined water table in geologic units that are not aquifers (for example, in glacial till or finegrained lake sediments). With the cooperation of the ISGS, I have developed a model (Seller and Berg, in press) for the regional assessment of aquifer contamination potential that is based on ISGS techniques, adapted to a broader map area where detailed information may be unavailable. This model was used to generate a map of aquifer contamination potential for an area encompassing parts of five states near southern Lake Michigan and Lake Erie; the model and map are currently being refined and evaluated.

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