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USGS1975

Water resources of the Mississippi and Sauk Rivers Watershed, central Minnesota

A variety of glacial landforms (moraines, till plains, drumlin fields and outwash plains) characterized the 3,890-square mile Mississippi and Sauk Rivers watershed. Underlying the glacial drift are Cambrian and Precambrian sedimentary rocks in the southeastern part of the watershed and Precambrian igneous and metamorphic rocks elsewhere. Surface drainage is entirely to the Mississippi River, the largest tributary being the Sauk River, which drains an area of about 970 square miles. The Mississippi follows a regional topographic low and transects the watershed from north to south. Greatest relief is in the morainal area in the west-central part of the watershed. The outwash plain in the southeastern part of the watershed and associated terrace deposits along the Mississippi River form a large area of relatively low relief. Details of topography are shown on 7 ½ and 15’ U.S. Geological Survey quadrangle maps, as indexed. Agriculture is the major economic activity. Small communities are scattered throughout the watershed; most larger municipalities and related development are concentrated along the Mississippi River. Lakes and streams offer good recreational opportunities.

Minnesota↗

USGS1950

Geology and paleontology of the Santa Maria district, California

Stratigraphy, paleontology, and geologic history.-A basement' consisting of igneous rocks of the Jurassic(?) Franciscan formation and sediments of the Upper Jurassic Knoxville formation, and formations of Tertiary and Quaternary age are exposed in the Santa Maria district. The outcrop section, exclusive of the Franciscan, has a maximum thickness of about 10,000 feet, the subsurface section about 27,000 feet. At no locality, however, is either outcrop or subsurface section as thick as the total maxima for the formations. The outcrop Franciscan is made up of altered basalt, gabbro (generally- greatly altered), and minor areas of peridotite and serpentine. The marine Knoxville formation, consisting of shale, thin-bedded calcareous sandstone, and conglomerate, was deposited on the igneous rocks of the Franciscan. It has an outcrop thickness of about 500 feet and a known subsurface thickness of at least 1,250 feet. Aucella cf. A. piochii, which occurs in both outcrop and subsurface sections, suggests late Jurassic age. The Franciscan and Knoxville were probably uplifted during Taliaferro's Diablan orogeny at the close of the Jurassic and formed a land area that presumably endured during early Cretaceous and perhaps during much of late Cretaceous time. If sediments were laid down while 10,000 feet of Upper Cretaceous were deposited in the adjoining San Rafael Mountains, they were eroded following uplift at the close of the Cretaceous, when Reed and Hollister's San Rafael uplift was formed. The district is inferred to have been part of a Franciscan and Knoxville land area at the south border of the San Rafael uplift during all of early Tertiary time. The known history of the district as part of a Tertiary basin began in the early Miocene(?), possibly a little earlier or possibly 3: little later, when the nonmarine sediments of the early Miocene(?) Lospe formation were deposited. The Lospe formation has a maximum thickness of 2, 700 feet, and is made up of coarse-grained reddish sandstone and conglomerate, and greenish sandstone, gypsiferous siltstone, and mudstone. White tuff is a minor but conspicuous constituent. The Lospe formation overlies the Knoxville, or· overlaps it and rests on the Franciscan. The first known Tertiary invasion of the sea took place immediately thereafter in early middle Miocene time, and from then on until approximately the end of the Pliocene the sea occupied continuously at least most of the region. The extent of the Miocene basin is not certainly known, but it was part of an extensive· basin that has been designated the Santa Barbara embayment. The early middle Miocene Point Sal formation is the earliest marine Tertiary formation. It has an outcrop thickness of as much as 1,500 feet and a maximum subsurface thickness of 3,600 feet, and consists of siltstone, mudstone, and thin beds of sandstone. The Point Sal formation overlies the Lospe formation without marked discontinuity, or overlaps it and rests on Knoxville or Franciscan. It contains a large foraminiferal fauna representing the Siphogenerina hughesi zone, or the lower part of Kleinpell's Relizian stage. The Monterey shale overlies the Point Sal formation without noticeable discontinuity, or overlaps all the older sedimentary formations and rests on the Franciscan. It has a maximum outcrop thickness of 2,100 feet, but is as much as 5,000 feet thick in some subsurface sections. The Monterey is divided into three mapped members. The lower member is characterized by phosphatic shale and somewhat porcelaneous shale; the middle member by chert and cherty shale; and the upper member by porcelaneous shale, or by both porcelaneous shale and diatomaceous strata. The lower member contains Foraminifera representing the upper part of Kleinpell's Relizian stage and all of his Luisian stage, the middle member a few species indicating the lower part of his Mohnian stage, and the upper member a fauna representing the upper part of the Bolivina hughesi zone, at the top of the Mohnian, and in part a younger unnamed faunal division; that is, the Monterey is of late middle and late Miocene age. The diverse stratigraphic relations of the Lospe and Point Sal formations and Monterey shale along the borders of the Franciscan rocks forming Point Sal Ridge are inferred to be the result of repeated movements during Miocene time in the area of basement rocks west of the district, presumably extending westward beyond the present coast. Toward the close of the Miocene, low ridges appeared on the floor of the sea, ridges that grew during Pliocene time and were destined to become anticlines. At the same time deformation took place in the northeastern part of the district, and elsewhere on some anticlines, or on other structural highs bounded by faults. In those areas the Sisquoc formation overlies the Monterey shale with marked discordance; elsewhere there is no discordance. Two facies of the Sisquoc formation are mapped: a marginal sandstone facies, designated the Tinaquaic sandstone member, and a basin facies. The Tinaquaic sandstone member is 1,400 feet thick and contains megafossils of middle Pliocene age (also early Pliocene just east of the mapped area). It is unconformable on the Monterey. The basin facies, at least 3,000 feet thick in outcrop sections and 5,000 in some subsurface sections, consists of diatomaceous mudstone, other types of diatomaceous ·strata, somewhat porcelaneous mudstone, and porcelaneous shale-deposits that are ordinarily characteristic of the Monterey shale. Even in areas where the two formations are lithologically indistinguishable and conformable, a field basis for differentiating them has been established. The basin facies of the Sisquoc conformably overlies the Monter.ey in outcrop sections, but in some subsurface sections the formations are unconformable, and on the north limb of the Santa Maria Valley syncline the basin facies of the Sisquoc overlaps the Monterey onto the basement, thus forming the overlap trap for the oil in the Monterey in the Santa Maria Valley field. The lower and middle parts of the basin facies contain Foraminifera of the Bolivina obliqua zone. Kleinpell assigned that zone to the lower part of his late upper Miocene Delmontian stage. Assignment to the upper Delmontian, however, appears to be preferable. The upper few hundred feet of the basin facies contain Foraminifera similar to those in the overlying Foxen mudstone and megafossils of middle Pliocene affinities. The basin facies is therefore considered late upper Miocene to middle Pliocene. The submarine ridges were growing during Pilocene time. The Foxen mudstone is missing on them and in the northeastern part of the district. On the north limb of the Santa Maria Valley syncline, the Foxen overlaps the Sisquoc formation and rests on the basement. In the basins between the submarine ridges, the mudstone, siltstone, and fine-grained sandstone of the Foxen (800 feet thick in outcrop sections and as much as 2, 750 in subsurface sections) overlie conformably the Sisquoc formation. In some of the areas where the Foxen is missing as a lithologic unit, it appears to be represented by condensed deposits of phosphatic pellets, mapped with the underlying or overlying Formation, depending on the matrix, or by a condensed section of fine-grained sand, mapped with lithologically indistinguishable sand in the basal part of the overlying formation. Though foraminifera are abundant in the Foxen mudstone, relatively few species are represented. Those from the lower part of the formation may be of middle Pliocene age. Megafossils from the upper part of the Foxen are considered late Pliocene. The formation is therefore assigned to the middle(?) and upper Pliocene. Movements during Pliocene time in the basement area west of Point Sal Ridge are indicated by the occurrence in the western Casmalia Hills of coarse detritus from the Monterey in the upper part of the Sisquoc formation and in the Foxen mudstone. During late Pliocene time, when the Careaga sandstone was deposited, the Pliocene sea had its greatest extent. The region then flooded may be referred to as the Santa Maria basin. Throughout most of the district two mapped members of the Careaga sandstone are differentiated: the Cebada fine-grained member, which has a maximum outcrop thickness of 1,000 feet, and the Graciosa coarse-grained member, 50 to 425 feet thick. Mild deformation continued during the late Pliocene. The Cebada fine-grained member is missing on the embryonic anticlines, where it is overlapped by the Graciosa coarse-grained member. Both members of the Careaga sandstone contain a large megafauna. The nonmarine Paso Robles formation conformably overlies the Careaga sandstone. The Paso Robles consists chiefly of sand and gravel, but clay, marl, and limestone are the most characteristic constituents. The maximum outcrop thickness is 2,000 feet, the estimated maximum subsurface thickness 4,500 feet. The Paso Robles fresh-water fauna is meager, consisting of a few species similar to living forms. The formation is currently assigned to the interval including late Pliocene and early Pleistocene(?). The age assignment late Pliocene(?) and early Pleistocene, however, may be preferable for the Santa Maria district. Then followed the only period of strong general deformation in the known Tertiary and Pleistocene history of the district. The present structural features of the district were formed at that time, and the submarine ridges appeared as fully formed anticlines. Dating of the deformation is uncertain, because of uncertainty concerning the age of the Paso Robles formation. It is, however, without much doubt of the same age as the welldated strong middle Pleistocene deformation in the Ventura basin. Terrace deposits, laid down on both wave-cut and stream-cut platforms, are rather arbitrarily assigned to the late Pleistocene. The oldest and most extensive terrace deposits, not more than 100 feet thick, are designated the Orcutt sand. The Orcutt sand itself is tilted as much as 12° on the limbs of anticlines and is faulted on the north limb of the Graciosa anticline, indicating renewed growth of the anticlines, presumably in late Pleistocene time. Terrace deposits apparently younger than the Orcutt sand are arched in a low anticline west of lower Foxen Canyon. Structure.-Santa Maria Valley is the boundary between two structural provinces. To the north, valleys and hills are either synclines or anticlines. To the south, on the contrary, major valleys coincide generally with major synclines, and the hills are anticlinal. Santa Maria Valley itself is a syncline. Unlike valleys farther south in the district, however, it lies athwart an older uplift. Also unlike most of the valleys farther south, the axis of the syncline is not in the middle of the valley, but is far to the south near the bordering hills. Indeed, in the western Casmalia Hills, the anticline in the bordering hills is overturned and overrides the axis of the syncline. The major structural features of the district have a general west-northwestward trend parallel to the trend of the basin. Minor westward-trending and northward-trending folds and faults, however, extend across the trend of the major features. The district includes areas of wide, open folds and also areas of narrow, closely spaced, and steeply tilted folds, as well as some major overturned anticlines, most of the latter overturned northward. The closely spaced folds coincide almost invariably with outcrops of the Monterey shale and Point Sal formation. Physiography.-The surface on which the terrace deposits, designated the Orcutt sand, were deposited is extensive but is locally deformed, and only remnants are preserved. Toward the coast it changes from a stream-cut surface to a wave-cut surface. In the coastal area three main marine terraces are recognized: the high terrace (altitude about 800 feet), the intermediate terrace (altitude about 600 feet), and the low terrace (altitude 50 to 125 feet). An indurated layer is present at or near the surface at many localities scattered throughout the district. It is suggested that the indurated layer is an ancient hardpan, the incomplete skeleton of a former soil profile developed on a former surface of less relief than the present surface. Sand dunes extend inland from the coast at the north and south borders of the mapped area. They are classified under three age groups: old, intermediate, and modern. The old dunes, which have a protective cover of natural vegetation and are now inactive, are far more extensive than those of the other two groups. They cover many square miles on a terrace bordering Santa Maria Valley, and extend 20 miles inland. It has not been determined whether their inactivity is due to a cutting off of the supply of sand, or to a climatic change. Occurrence of oil.--Oil has been produced in the Santa Maria district since 1901, the total production to the end of 1947 being 269,657,000 barrels. Throughout the district most of the oil is heavy. Seven producing fields are located in the mapped area. In order of discovery from oldest to youngest the fields are as follows: Orcutt, Lompoc, West Cat Canyon, East Cat Canyon, Casmalia, Gato Ridge, and Santa Maria Valley. The Santa Maria Valley field is the largest in both area and productive capacity. It is the largest overlap field in coastal California, and one of the last major fields found in the State up to 1947. The Las Flores (Monterey) pool is transforming the West Cat Canyon field into one of the major fields of the district. The Monterey shale is the chief oil-bearing formation, and the principal reservoir in the Monterey consists of fractured chert and cherty shale. Sand in the Sisquoc formation is the sole reservoir in the minor East Cat Canyon field and in the Pliocene pool of the West Cat Canyon field. The Point Sal formation yields some oil in the southeastern part of the Santa Maria Valley field (the only part of that field where the formation is present) and a recent well in the Casmalia field is producing a small amount of relatively light oil from the Point Sal. The Lospe formation is also productive in a recent well in the Casmalia field. The Knoxville formation is productive in three areas in the northern part of the Santa Maria Valley field. The Point Sal formation offers the greatest promise for deeper-zone production. The Lospe and Knoxville formations can no longer be ignored in areas where younger marine formations overlap against them. Oil possibilities in undeveloped areas.--Two matters weigh heavily in prospecting in the Santa Maria district: the degree of fracturing of chert and cherty shale in the Monterey shale, and the gravity of the oil. Other things being equal, the productivity of the Monterey varies directly with the amount of fracturing. Very heavy oil, too heavy to produce commercially under present conditions, has befln found ii the Monterey in the northeastern part of the district, where five discoveries (one east of the mapped area) have been made in recent years. Among areas of possible interest, three appear to be favorable for prospecting on the basis of surface geology: an area east of Foxen Canyon, where oil may be trapped in the basal part of the Tinaquaic sandstone member of the Sisquoc formation by westward overlap of successively higher Tinaquaic strata onto the Monterey shale; an area so1tth of the I ... ions Head fault, where oil may be trapped by the fault; and the offshore extension of the north border of Point Sal Ridge, where oil may possibly be trapped in the Monterey by overlap of the Sisquoc formation.

California↗

USGS2016

Assessing conditions influencing the longitudinal distribution of exotic brown trout (Salmo trutta) in a mountain stream: a spatially-explicit modeling approach

Trout species often segregate along elevational gradients, yet the mechanisms driving this pattern are not fully understood. On the Logan River, Utah, USA, exotic brown trout ( Salmo trutta ) dominate at low elevations but are near-absent from high elevations with native Bonneville cutthroat trout ( Onchorhynchus clarkii utah ). We used a spatially-explicit Bayesian modeling approach to evaluate how abiotic conditions (describing mechanisms related to temperature and physical habitat) as well as propagule pressure explained the distribution of brown trout in this system. Many covariates strongly explained redd abundance based on model performance and coefficient strength, including average annual temperature, average summer temperature, gravel availability, distance from a concentrated stocking area, and anchor ice-impeded distance from a concentrated stocking area. In contrast, covariates that exhibited low performance in models and/or a weak relationship to redd abundance included reach-average water depth, stocking intensity to the reach, average winter temperature, and number of days with anchor ice. Even if climate change creates more suitable summer temperature conditions for brown trout at high elevations, our findings suggest their success may be limited by other conditions. The potential role of anchor ice in limiting movement upstream is compelling considering evidence suggesting anchor ice prevalence on the Logan River has decreased significantly over the last several decades, likely in response to climatic changes. Further experimental and field research is needed to explore the role of anchor ice, spawning gravel availability, and locations of historical stocking in structuring brown trout distributions on the Logan River and elsewhere.

Utah↗

USGS2015

Evidence for episodic acidification effects on migrating Atlantic salmon Salmo salar smolts

Field studies were conducted to determine levels of gill aluminium as an index of acidification effects on migrating Atlantic salmon Salmo salar smolts in the north-eastern U.S.A. along mainstem river migration corridors in several major river basins. Smolts emigrating from the Connecticut River, where most (but not all) tributaries were well buffered, had low or undetectable levels of gill aluminium and high gill Na + /K + -ATPase (NKA) activity. In contrast, smolts emigrating from the upper Merrimack River basin where most tributaries are characterized by low pH and high inorganic aluminium had consistently elevated gill aluminium and lower gill NKA activity, which may explain the low adult return rates of S. salar stocked into the upper Merrimack catchment. In the Sheepscot, Narraguagus and Penobscot Rivers in Maine, river and year-specific effects on gill aluminium were detected that appeared to be driven by underlying geology and high spring discharge. The results indicate that episodic acidification is affecting S. salar smolts in poorly buffered streams in New England and may help explain variation in S. salar survival and abundance among rivers and among years, with implications for the conservation and recovery of S. salar in the north-eastern U.S.A. These results suggest that the physiological condition of outmigrating smolts may serve as a large-scale sentinel of landscape-level recovery of atmospheric pollution in this and other parts of the North Atlantic region.

Journal of Fish Biology↗

USGS2003

Geologic map of the La Mesita Negra SE Quadrangle, Bernalillo County, New Mexico

Geologic mapping, in support of the USGS Middle Rio Grande Basin Geologic Mapping Project, shows the spatial distribution of artificial-fill, alluvial, colluvial, and eolian deposits, lava flows and related sediments of the Albuquerque volcanoes, and upper Santa Fe Group sediments. These deposits are on, beneath, and along the West Mesa (Llano de Albuquerque) just west of Albuquerque, New Mexico. Artificial fill deposits are mapped chiefly beneath and near segments of Interstate 40, in an inactive landfill (or dump) north of Interstate 40 near the eastern boundary of the map area, and in the active Cerro Colorado landfill near the southwestern corner of the map area. Alluvial deposits are mapped in stream channels, beneath treads of terraces, and on hill slopes. They include alluvium in stream channels and beneath treads of low terraces, terrace alluvium, sheetwash deposits, gravelly alluvium, and old alluvium and calcic soils of the Llano de Albuquerque. Alluvial and colluvial deposits are mapped on hill slopes. They include young alluvial-slope deposits, alluvium and colluvium, undivided, and old alluvial-slope deposits. Colluvial deposits are also mapped on hill slopes. They include colluvial deposits, undivided, as well as alluvial deposits, eolian sand, and calcic soils associated with fault scarps. Eolian deposits as well as eolian and alluvial deposits mantle gently slopping surfaces on the Llano de Albuquerque. They include active eolian sand, active and inactive eolian sand and sheetwash deposits, undivided, and inactive eolian sand and sheetwash deposits, undivided. Lava flows and related sediments of the Albuquerque volcanoes were mapped near the southeast corner of the map area. They include five young lava flows, two young cinder deposits, and old lava flows. Upper Santa Fe Group sediments are well exposed and mapped in the western part of the map area. They include a gravel unit, a pebbly sand unit, and a mud and sand unit. Undivided upper Santa Fe Group sediments were mapped in the eastern part of the map area. Sediments and lava flows in the map area record alluvial, eolian, colluvial, and volcanic processes of the past several million years. The surficial deposits (post-Santa Fe Group sediments) on the map are known or estimated to be at least 1 m thick; most deposits are poorly exposed. Thin (< 50 cm), discontinuous deposits of eolian sand and sheetwash (Qea, Qes, and Qsw) locally are present on gently sloping map units older than the alluvium in stream channels and low terraces (Qa). These thin eolian and sheetwash deposits are not mapped, but they are widespread on the gravel unit of the upper Santa Fe Group sediments (Tg) on the eastern flank of the Llano de Albuquerque, near the eastern boundary of the map area (quadrangle). Small deposits of artificial fill (af) less than about 25 m wide are not mapped. Fractional map symbols (for example, Qsw/Qby1) are used where sheetwash deposits mantle lava flows. These fractional units are not described here; instead refer to descriptions of individual units.

Miscellaneous Field Studies Map↗

USGS2000

Proposal and work plan to calibrate and verify a water-quality model to simulate effects of wastewater discharges to the Red River of the North at drought streamflow near Fargo, North Dakota, and Moorhead, Minnesota

This report presents a proposal for conducting a water-quality modeling study at drought streamflow, a detailed comprehensive plan for collecting the data, and an annual drought-formation monitoring plan. A 30.8 mile reach of the Red River of the North receives treated wastewater from plants at Fargo, North Dakota, and Moorhead, Minnesota, and streamflow from the Sheyenne River. The water-quality modeling study will evaluate the effects of continuous treated-wastewater discharges to the study reach at drought streamflow. The study will define hydraulic characteristics and reaeration and selected reaction coefficients and will calibrate and verity a model. The study includes collecting synoptic water-quality samples for various types of analyses at a number of sites in the study reach. Dye and gas samples will be collected for traveltime and reaeration measurements. Using the Lagrangian reference frame, synoptic water-quality samples will be collected for analysis of nutrients, chlorophyll a, alkalinity, and carbonaceous biochemical oxygen demand. Field measurements will be made of specific conductance, pH, air and water temperature, dissolved oxygen, and sediment oxygen demand. Two sets of water-quality data will be collected. One data set will be used to calibrate the model, and the other data set will be used to verity the model. The DAFLOW/BLTM models will be used to evaluate the effects of the treated wastewater on the water quality of the river. The model will simulate specific conductance, temperature, dissolved oxygen, carbonaceous biochemical oxygen demand, total nitrogen (organic, ammonia, nitrite, nitrate), total orthophosphorus, total phosphorus, and phytoplankton as chlorophyll a. The work plan identifies and discusses the work elements needed for accomplishing the data collection for the study. The work elements specify who will provide personnel, vehicles, instruments, and supplies needed during data collection. The work plan contains instructions for data collection; inventory lists of needed personnel, vehicles, instruments, and supplies; and examples of computations for determining quantities of tracer to be injected into the stream. The work plan also contains an annual drought-formation monitoring plan that includes a 9-month time line that specifies when essential planning actions must occur before actual project start up. Drought streamflows are rare. The annual drought-formation monitoring plan is presented to assist project planning by providing early warning that conditions are favorable to produce drought streamflow. The plan to monitor drought-forming conditions discusses the drought indices to be monitored. To establish a baseline, historic values for some of the drought indices for selected years were reviewed. An annual review of the drought indices is recommended.

Open-File Report↗

USGS1997

Estimated rate of recharge in outcrops of the Chicot and Evangeline aquifers near Houston, Texas

During 1989-90, the U.S. Geological Survey (USGS), in cooperation with the Harris-Galveston Coastal Subsidence District, conducted a field study to determine the depth to the water table and to estimate the rate of recharge in outcrops of the Chicot and Evangeline aquifers near Houston, Texas. The study area (fig. 1) comprises about 2,000 square miles of outcrops of the Chicot and Evangeline aquifers in northwestern Harris County, Montgomery County, and southern Walker County. The depth to the water table was estimated using seismic refraction, and an estimated rate of recharge in the aquifer outcrops was computed using the tritium-interface method (Andres and Egger, 1985) in which environmental tritium is the ground-water tracer. The water table generally ranges in depth between 10 and 30 feet in the study area, and the average total recharge rate was estimated to be not larger than 6 inches per year. The rate is total recharge to the saturated zone, rather than net recharge to the deep regional flow system. The total recharge can be reduced by evapotranspiration and by local discharge, mainly to streams. These results are published in USGS Water-Resources Investigations Report 96-4018 (Noble and others, 1996). A second study of environmental tritium in the same area as the 1989-90 study, also in cooperation with the Harris-Galveston Coastal Subsidence District, was done in 1996 to confirm the results of the original study. This fact sheet documents the estimation of an upper limit on the average total recharge rate on the basis of the vertical movement of tritium in ground water during 1953-89 and during 1953-95.

Fact Sheet↗

USGS1965

An evaluation of aquifer and well characteristics of municipal well fields in Los Alamos and Guaje Canyons, near Los Alamos, New Mexico

The Jenkins-Whitesburg area includes approximately 250 square miles In Letcher and Pike Counties in the southeastern part of the Eastern Coal Field. In this area ground water is the principal source of water for nearly all rural families, most public supplies, several coal mines and coal processing plants, and one bottling plant. The major aquifers in the Jenkins-Whitesburg area are the Breathitt and Lee Formations of Pennsylvanian age. Other aquifers range in age from Devonian to Quaternary but are not important in this area because they occur at great depth or yield little or no water. The Breathitt Formation occurs throughout the area except along the crest and slopes of Pine Mountain and where it is covered by unconsolidated material of Quaternary age. The Breathitt Formation consists of shale, sandstone, and lesser amounts of coal and associated underclay. The yield of wells penetrating the Breathitt Formation ranges from less than 1 to 330 gallons per minute. Well yield is controlled by the type and depth of well, character of the aquifer, and topography of the well site. Generally, deep wells drilled in valleys of perennial streams offer the best potential for high yields. Although enough water for a minimum domestic supply (more than 100 gallons per day) may be obtained from shale, all high-yielding wells probably obtain water from vertical joints and from bedding planes which are best developed in sandstone. About 13 percent of the wells inventoried in the Breathitt Formation failed to supply enough water for a minimum domestic supply. Most of these are shallow dug wells or drilled wells on hillsides or hilltops. Abandoned coal dunes are utilized as large infiltration galleries and furnish part of the water for several public supplies. The chemical quality of water from the Breathitt Formation varies considerably from place to place, but the water generally is acceptable for most domestic and industrial uses. Most water is a calcium magnesium bicarbonate or sodium bicarbonate type, and nearly all sampled water contained enough iron to stain cooking and laundry utensils. The water ranged from soft to very hard, and only one well in the Breathitt Formation produced salty water. The absence of salty water may be due to abundant fractures which are associated with the Pine Mountain fault and which have allowed fresh water to enter the formation. The Lee Formation underlies the Cumberland Mountain section and is exposed along the crest and southeast slope of Pine Mountain. The Lee Formation consists of massive sandstone and conglomerate with thin beds of shale and a few thin coal seams. Although the Lee Formation is tapped by only a few wells in this area, it is potentially an important aquifer. Wells penetrating the Lee Formation in the Cumberland Mountain section would probably yield water under artesian pressure. Unlike most water from the Lee Formation in other part.3 of eastern Kentucky, all water from the Lee Formation in the Jenkins-Whitesburg area is fresh. All water from the Lee Formation contained more than 0.3 parts per million of iron and ranged from soft to moderately hard.

Water Supply Paper↗

USGS1965

Water-supply potential from an asphalt-lined catchment near Holualoa Kona, Hawaii

The Jenkins-Whitesburg area includes approximately 250 square miles In Letcher and Pike Counties in the southeastern part of the Eastern Coal Field. In this area ground water is the principal source of water for nearly all rural families, most public supplies, several coal mines and coal processing plants, and one bottling plant. The major aquifers in the Jenkins-Whitesburg area are the Breathitt and Lee Formations of Pennsylvanian age. Other aquifers range in age from Devonian to Quaternary but are not important in this area because they occur at great depth or yield little or no water. The Breathitt Formation occurs throughout the area except along the crest and slopes of Pine Mountain and where it is covered by unconsolidated material of Quaternary age. The Breathitt Formation consists of shale, sandstone, and lesser amounts of coal and associated underclay. The yield of wells penetrating the Breathitt Formation ranges from less than 1 to 330 gallons per minute. Well yield is controlled by the type and depth of well, character of the aquifer, and topography of the well site. Generally, deep wells drilled in valleys of perennial streams offer the best potential for high yields. Although enough water for a minimum domestic supply (more than 100 gallons per day) may be obtained from shale, all high-yielding wells probably obtain water from vertical joints and from bedding planes which are best developed in sandstone. About 13 percent of the wells inventoried in the Breathitt Formation failed to supply enough water for a minimum domestic supply. Most of these are shallow dug wells or drilled wells on hillsides or hilltops. Abandoned coal mines are utilized as large infiltration galleries and furnish part of the water for several public supplies. The chemical quality of water from the Breathitt Formation varies considerably from place to place, but the water generally is acceptable for most domestic and industrial uses. Most water is a calcium magnesium bicarbonate or sodium bicarbonate type, and nearly all sampled water contained enough iron to stain cooking and laundry utensils. The water ranged from soft to very hard, and only one well in the Breathitt Formation produced salty water. The absence of salty water may be due to abundant fractures which are associated with the Pine Mountain fault and which have allowed fresh water to enter the formation. The Lee Formation underlies the Cumberland Mountain section and is exposed along the crest and southeast slope of Pine Mountain. The Lee Formation consists of massive sandstone and conglomerate with thin beds of shale and a few thin coal seams. Although the Lee Formation is tapped by only a few wells in this area, it is potentially an important aquifer. Wells penetrating the Lee Formation in the Cumberland Mountain section would probably yield water under artesian pressure. Unlike most water from the Lee Formation in other part.3 of eastern Kentucky, all water from the Lee Formation in the Jenkins-Whitesburg area is fresh. All water from the Lee Formation contained more than 0.3 parts per million of iron and ranged from soft to moderately hard.

Water Supply Paper↗

USGS2016

Complex mixtures, complex responses: Assessing pharmaceutical mixtures using field and laboratory approaches

Pharmaceuticals are present in low concentrations (<100 ng/L) in most municipal wastewater effluents but may be elevated locally because of factors such as input from pharmaceutical formulation facilities. Using existing concentration data, the authors assessed pharmaceuticals in laboratory exposures of fathead minnows ( Pimephales promelas ) and added environmental complexity through effluent exposures. In the laboratory, larval and mature minnows were exposed to a simple opioid mixture (hydrocodone, methadone, and oxycodone), an opioid agonist (tramadol), a muscle relaxant (methocarbamol), a simple antidepressant mixture (fluoxetine, paroxetine, venlafaxine), a sleep aid (temazepam), or a complex mixture of all compounds. Larval minnow response to effluent exposure was not consistent. The 2010 exposures resulted in shorter exposed minnow larvae, whereas the larvae exposed in 2012 exhibited altered escape behavior. Mature minnows exhibited altered hepatosomatic indices, with the strongest effects in females and in mixture exposures. In addition, laboratory-exposed, mature male minnows exposed to all pharmaceuticals (except the selective serotonin reuptake inhibitor mixture) defended nest sites less rigorously than fish in the control group. Tramadol or antidepressant mixture exposure resulted in increased splenic T lymphocytes. Only male minnows exposed to whole effluent responded with increased plasma vitellogenin concentrations. Female minnows exposed to pharmaceuticals (except the opioid mixture) had larger livers, likely as a compensatory result of greater prominence of vacuoles in liver hepatocytes. The observed alteration of apical endpoints central to sustaining fish populations confirms that effluents containing waste streams from pharmaceutical formulation facilities can adversely impact fish populations but that the effects may not be temporally consistent. The present study highlights the importance of including diverse biological endpoints spanning levels of biological organization and life stages when assessing contaminant interactions.

Environmental Toxicology and Chemistry↗

USGS1954

Preliminary report of investigations of springs in the Mogollon Rim region Arizona

The Geological Survey has made a reconnaissance of springs in the Mogollon Rim region in central Arizona. This region is the source of much of the water in the Gila, Salt, and Verde Rivers. The region has not previously been systematically studied with respect to the occurrence of ground water. The Mogollon Rim is an escarpment that extends about 200 miles in a northwest direction from near Clifton and Morenci in southeastern Arizona and gradually disappears north of Prescott. Lumbering, ranching, and in local areas copper mining are the principal industries. Main lines of drainage extend north on the plateau, north of the rim, and south or southwest below the rim. For convenience in discussion and because of structural differences, the region has been separated into western, central, and eastern divisions. Pre-Cambrian to Recent rocks crop out. Pre-Cambrian formations and those of Paleozoic age constitute the thickest sections. Recent basalt flows cap the plateau portion, except in the central part of the region. Large areas in valleys below the rim are occupied by lake-bed deposits. The valleys are aligned northwest, suggesting the possibility that a structural trough extends almost the full length of the rim southwest of the scarp. In some areas, erosion has caused recession of the escarpment for distances of a few miles to 10 or 15 miles from the major rim faults. The origin of late deposits of sodium Sulfate in the Verde basin has not been adequately, explained. As the salts are concentrated near mineralized districts on the southwest side of the basin, a possible genetic relationship between the two should be considered. Pre-Cambrian granite and basalt of probable Tertiary and Quaternary age are the igneous rocks most widely exposed in the region. Diabase dikes and sills are prominent in some areas; they were intruded probably during Late Cambrian time. A thickness of 2,000 feet of volcanic rocks of probable Cretaceous and Tertiary age is exposed in one area along the rim, but these rocks as yet have not been studied in detail. A hypothetical relationship is advanced to explain the coincidence in estimated volumes of rock erupted in the San Franciscan volcanic field and the volumes displaced by subsidence of the Verde basin. Fold structures are relatively uncommon in the region and are of small extent except the Holbrook dome northwest of Snowflake. High-angle faults, for the most part normal, are the most prominent structures identified. Faults parallel to the rim have been mapped in several areas. The inferred relations are shown on three diagrammatic sections. These faults are thought to account for the presence of two rims in the eastern division, and perhaps as many as three near Payson. Major orogeny in the region is believed to have occurred four times, as follows: (1) In the pre-Cambrian; (2) in Miocene(?) time southwest of the Mogollon escarpment; (3) in Pliocene (?) time at least in the Flagstaff area, and; (4) at or near the beginning of Quaternary time. The Laramide structures, prominent elsewhere on the plateau, are reflected only weakly in the rim region, so far as is known. Studies of perennial base flow of major streams draining southward from the rim indicate a sustained yield of about 175 cfs (cubic feet per second) measured at existing gaging stations. Runoff records and partial seepage runs show a loss of water between the upper reaches of the streams and the storage reservoirs. There is a general tendency for the water to become progressively more highly mineralized with increasing distance from headwater springs. Natural lakes, ponds, swamps, and cienagas are common in the eastern and western divisions of the rim. They lose considerable water, and some are fully desiccated each summer. They are of little use in their present condition, but might be developed as natural water catches from which recharge co

Open-File Report↗

USGS1997

National Geochemical Database: Reformatted data from the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program

The National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program produced a large amount of geochemical data. To fully understand how these data were generated, it is recommended that you read the History of NURE HSSR Program for a summary of the entire program. By the time the NURE program had ended, the HSSR data consisted of 894 separate data files stored with 47 different formats. Many files contained duplication of data found in other files. The University of Oklahoma's Information Systems Programs of the Energy Resources Institute (ISP) was contracted by the Department of Energy to enhance the accessibility and usefulness of the NURE HSSR data. ISP created a single standard-format master file to replace the 894 original files. ISP converted 817 of the 894 original files before its funding apparently ran out. The ISP-reformatted NURE data files have been released by the USGS on CD-ROM (Lower 48 States, Hoffman and Buttleman, 1994; Alaska, Hoffman and Buttleman, 1996). A description of each NURE database field, derived from a draft NURE HSSR data format manual (unpubl. commun., Stan Moll, ISP, Oct 7, 1988), was included in a readme file on each CD-ROM. That original manual was incomplete and assumed that the reformatting process had gone to completion. A lot of vital information was not included. Efforts to correct that manual and the NURE data revealed a large number of problems and missing data. As a result of the frustrating process of cleaning and re-cleaning data from the ISP-reformatted NURE files, a new NURE HSSR data format was developed. This work represents a totally new attempt to reformat the original NURE files into 2 consistent database structures; one for water samples and a second for sediment samples, on a quadrangle by quadrangle basis, from the original NURE files. Although this USGS-reformatted NURE HSSR data format is different than that created by the ISP, many of their ideas were incorporated and expanded in this effort. All of the data from each quadrangle are being examined thoroughly in an attempt to eliminate problems, to combine partial or duplicate records, to convert all coding to a common scheme, and to identify problems even if they can not be solved at this time.

Open-File Report↗

USGS1995

Verification of water-quality model to simulate effects of discharging treated wastewater during ice-cover conditions to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota

The Red River at Fargo Water-Quality (RRatFGO QW) Model, which used the Enhanced Stream Water Quality Model (QUAL2E) computer program, was calibrated and verified for icefree conditions. The purpose of this study was to verify the model for ice-cover conditions using the same Red River of the North study reach that was used for ice-free conditions. The study reach begins about 0.1 mile downstream of the 12th Avenue North bridge in Fargo, North Dakota, and extends 30.8 miles downstream to a site 0.8 mile upstream of the confluence of the Buffalo River and the Red River of the North. The study reach receives treated wastewater outflow from municipal wastewater-treatment plants at Fargo, North Dakota, and Moorhead, Minnesota, and inflow from the Sheyenne River. For simulations conducted for ice-cover conditions, the RRatFGO QW Model will be referred to as the Red River at Fargo Ice-Cover Water-Quality (RRatFGOIC QW) Model. Streamflow measurements were made at 10 sites during February 21-24, 1995, and water-quality samples were collected and field properties were measured at 12 sites during February 23-24, 1995. Properties and constituents analyzed for include specific conductance, water temperature, dissolved oxygen, 5-day carbonaceous biochemical oxygen demand, total nitrite (reported as nitrogen), total nitrite plus nitrate (reported as nitrogen), total ammonia (reported as nitrogen), total organic nitrogen (reported as nitrogen), total phosphorus (reported as phosphorus), chlorophyll a, and algal biomass. The RRatFGOIC QW Model simulated streamflow, specific conductance, total organic nitrogen, total ammonia, total nitrite, total nitrite plus nitrate, 5-day carbonaceous biochemical oxygen demand, and dissolved oxygen. The model was considered verified for ice-cover conditions for all of the values or concentrations simulated except for the total organic nitrogen concentrations. Based on the results of this study, the QUAL2E Model computer program that was calibrated for ice-free conditions is capable of simulating water quality for both ice-free and ice-cover conditions.

Water-Resources Investigations Report↗

USGS1982

Maps and interpretation of geochemical anomalies in the John Muir Wilderness, Fresno, Inyo, Madera and Mono counties, California

A geochemical survey of the John Muir Wilderness was conducted by the U.S. Geological Survey between 1969 and 1978. The 755-mi 2 (1,956-km 2 ) wilderness is located in the central Sierra Nevada, Calif. (fig. 1). Stream-sediment samples were collected at 1,434 sites in the wilderness and immediately adjacent areas. Analytical data for these samples and a map of smapling sites are presented by du Bray and Dellinger (1980) and Diggles and others (1981). A geologic map of the area was compiled by du Bray (1981). These maps and tables present the results of the analysis of geochemical data for lead, zinc, gold, silver, arsenic, chromium, molybdenum, manganese, tungsten, tin, copper, and nickel. These are elements of economic interest which have historically been found in mineral deposits of the Sierra Nevada or other geologically similar areas.

California↗

USGS2021

Simulation of dissolved organic carbon flux in the Penobscot Watershed, Maine

Dissolved organic carbon (DOC) is an important component of the carbon cycle as a measure of the hydrological transport of carbon between terrestrial carbon pools into soil pools and eventually into streams. As a result, changes in DOC in rivers and streams may indicate alterations in the storage of terrestrial carbon. Exploring the complex interactions between biogeochemical cycling and hydrologic processes, as well as the micro-climate variabilities that impact the rate of DOC fluxes, are challenging because the information is not readily available from in-situ measurements or from empirical models alone. This is particularly true of large-scale watersheds. The Penobscot Watershed is the largest watershed of the Gulf of Maine and the second largest in New England. Its typical soils, with high organic matter and a large forested and wetland landscape, result in higher DOC fluxes than what has been observed previously for most rivers in the northern temperate or boreal zones (Hope et al., 1994; Mulholland, 1997; Aitkenhead and McDowell, 2000). In this study, we emphasized the simulation of streamflow and DOC fluxes from the Penobscot Watershed (and several tributaries within the Penobscot Watershed) using the spatially distributed process-based Regional Hydro-Ecological Simulation System (RHESSys) model. Simulated results were evaluated using field measurements (streamflow, DOC fluxes) and remotely sensed products (Net Primary Production (NPP) and Leaf Area Index (LAI) from Moderate Resolution Imaging Spectroradiometer (MODIS). The average DOC flux for the Penobscot Watershed during 2004-2012 using the RHESSys model was 69 kg C/ha/year. The RHESSys simulated DOC flux is shown to correlate well with observed values, as well as with results previously reported from the empirical Load Estimator (LOADEST) model (71 kg C/ha/year) for 2004-2007 ( Huntington and Aiken, 2013). Our simulated results also show a temporal variation in the amount of DOC flux, indicating that the antecedent DOC concentration from one year can impact the DOC export in following years. Thus, DOC concentration is positively correlated with streamflow and antecedent precipitation, in agreement with previous studies (Ågren et al., 2010; Huntington and Aiken, 2013; Tian et al., 2013 ). The successful application of the rigorous RHESSys model in the Penobscot Watershed makes it a reasonable platform to test future scenarios impacting the hydrology and biogeochemistry within similar large complex watersheds.

Maine↗

USGS1994

Mineral-resource assessments in Alaska; background information to accompany maps and reports about the geology and undiscovered-mineral-resource potential of the Mount Katmai Quadrangle and adjacent parts of the Naknek and Afognak quadrangles, Alaska Peninsula

Geologic and geochemical field studies were carded out from 1983 to 1987 in the Mount Katmai l?x2 ? quadrangle and adjoining region, at the northeast end of the Alaska Peninsula. The region is nearly entirely within Katmai National Park and Preserve and has had almost no mineral production, so prior to this study there were few data by which to assess the mineral potential of the region. This report describes the folio of publications that have resulted from the study: geologic maps, geochemical results, fossil identifications, radiometric rock ages, and an assessment of the undiscovered-mineral-resource potential of the region. The Katmai region is inferred to potentially have three types of undiscovered mineral deposits: porphyry copper (molybdenum), precious-metal vein, and hot-springs gold. These deposit types occur elsewhere on the Alaska Peninsula in similar geologic units. Evidence suggesting their occurrence in the Katmai region is the presence of trace amounts of metals typically associated with these kinds of deposits in bedrock of certain tracts and in sediments of streams draining those tracts. Magma to provide heat, fractures to provide pathways for mineralizing fluids, and altered rock are required by genetic models of these deposit types. Such features do occur in the Katmai tracts. Confirmation of any mineral deposit in the Katmai region requires detailed follow-up sampling and acquisition of subsurface information, which is beyond the scope of this study. However, producing porphyry deposits are unknown elsewhere on the Alaska Peninsula in similar rocks, so if any such deposits occur in the Katmai region, they are likely to be few in number. Conversely, vein deposits are typically small in size so there may be several of such deposits. The properties and thermal history of the sedimentary rocks that could serve as reservoirs for oil or gas are unfavorable in adjacent regions. Thus the potential of the Katmai region for producible quantities of fossil fuels is low. In theory the region has shallow concentrations of geothermal fluids, but specific evidence for their presence is obscured by heavy precipitation and cold young rocks or deposits. Small volumes of coal occur at tidewater sites on the Pacific coast.

Circular↗

USGS2020

One-Water Hydrologic Flow Model: A MODFLOW based conjunctive-use simulation software

The U.S. Geological Survey’s (USGS) Modular Ground-Water Flow Model (MODFLOW-2005) is a computer program that simulates groundwater flow by using finite differences. The MODFLOW-2005 framework uses a modular design that allows for the easy development and incorporation of new features called processes and packages that work with or modify inputs to the groundwater-flow equation. A process solves a flow equation or set of equations. For example, the central part of MODFLOW is the groundwater-flow process that solves the groundwater-flow equation; the surface-water routing process is an additional process that solves the surface-water flow equation. Packages are code related to the groundwater-flow process. For example, the subsidence package modifies the groundwater-flow process by including aquifer compaction effects on flow. With the development of new packages and processes, the MODFLOW-2005 base framework diverged into multiple independent versions designed for specific simulation needs. This divergence limited each independent MODFLOW release to its specific purpose, so that there was no longer a single, comprehensive, general-purpose hydraulic-simulation framework. The MODFLOW One-Water Hydrologic Flow Model (MF-OWHM, also informally known as OneWater) is an integrated hydrologic flow model that combines multiple MODFLOW-2005 variants in one cohesive simulation software; changes were made to enable multiple capabilities in one code. This fusion of the MODFLOW-2005 versions resulted in a simulation software that can be used to address and analyze a wide class of conjunctive-use, water-management, water-food-security, and climate-crop-water scenarios. As a second core version of MODFLOW-2005, MF-OWHM maintains backward compatibility with existing MODFLOW-2005 versions, with features that include the following: Process-based simulation. Saturated groundwater flow (three-dimensional). Surface-water flow (one- and two-dimensional). Stream and river flow. Lake and reservoir storage. Landscape simulation and irrigated agriculture. Land-use and crop simulation. Root uptake of groundwater. Actual evapotranspiration. Estimated irrigation demand. Reservoir operations. Aquifer compaction and subsidence by vertical model-grid deformation. Seawater intrusion by a sharp-interface assumption. Karst-aquifer and fractured-bedrock flow. Turbulent and laminar-pipe network flow. Unsaturated groundwater flow (one-dimensional). Internal linkages among the processes that couple hydraulic head, flow, and deformation. Redesigned code for faster simulation, increased user-input options, easier model updates, and more robust error reporting than in previous models. MF-OWHM is a MODFLOW-2005 based integrated hydrologic model that can simulate and analyze varying environmental conditions to allow for the evaluation of management options from many components of human and natural water movement through a physically based, supply and demand framework. The term “integrated,” in the context of this report, refers to the tight coupling of groundwater flow, surface-water flow, landscape processes, aquifer compaction and subsidence, reservoir operations, and conduit (karst) flow. Another benefit of this integrated hydrologic model is that models developed to run by MODFLOW-2005, MODFLOW-NWT, MODFLOW-CFP, or MODFLOW-FMP can also be simulated with MF-OWHM. At the time of this report’s publication, MF-OWHM version 2 (MF-OWHM2) does not include a direct internal simulation of snowmelt, advanced mountainous watershed rainfall-runoff simulation, detailed shallow soil-moisture accounting, or atmospheric moisture content. Atmospheric moisture may be accounted for indirectly by, optionally, specifying a pan-evaporation rate, reference evapotranspiration, and precipitation. These features are not included to ensure that simulation runtime remains short enough to enable the use of automated methods of calibrating model parameters to field observations, which typically require many simulation model runs. The MF-OWHM approach is to include as much detail as possible to simulate hydrological processes, providing the simulation runtimes remain reasonable enough to allow for robust parameter estimation and model calibration. To represent both natural and human-influenced flow, MF-OWHM integrates physically based flow processes derived from MODFLOW-2005 in a supply and demand framework. From this integration, the physically based movement of groundwater, surface water, imported water, and precipitation serve as supply to meet consumptive demands associated with irrigated and non-irrigated agriculture, natural vegetation, and urban water uses. Water consumption is determined by balancing the available water supply with water demand, leading to the concept of a demand-driven, supply-constrained simulation. The MF-OWHM Supply-and-Demand Framework is especially useful for the analysis of agricultural water use, where there are often few data available to describe changes in land-use through time, such as crop type and distribution, and the associated changes in groundwater pumpage. This framework attempts to satisfy each land-use water demand with available water supplies—that is, groundwater uptake, precipitation, and irrigation. An option provided in MF-OWHM2 is to automatically increase groundwater pumping for irrigation, which often is unknown, by the calculated residual between demand and the other available sources of supply. From large- to small-scale applications, the physically based supply and demand framework provides key capabilities for simulating and analyzing historical, current, and future conjunctive-use of surface water and groundwater. To achieve the physically based supply and demand framework, the MODFLOW-2005 standard of no inter-package and -process communication was relaxed for MF-OWHM2. Traditional MODFLOW simulation models required that all packages and processes interact through the groundwater-flow equation or by removing the water flow from the simulation domain. For example, the MODFLOW-2005 representation of a groundwater well extracts water from the groundwater-flow equation (by subtraction) and removes it from the simulation domain. This feature is available in the MF-OWHM framework, but options have been added to allow the specification of a use or destination of pumped groundwater within the model domain, for example, it can be used for irrigation, managed aquifer recharge, or return-flow to streams.

Techniques and Methods↗

USGS2008

The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results

A mass of snow and ice 400-m-wide and 105-m-thick began melting in the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably owing to increased heat flux from the hydrothermal system, or possibly from magma intrusion and degassing. In early May 2005, an estimated 3.8??10 6 m 3 of sulfurous, clay-rich debris and acidic water, with an accompanying acidic aerosol component, exited the crater through a tunnel at the base of a glacier that breaches the south crater rim. Over 27 km downstream, the acidic waters of the flood inundated an important salmon spawning drainage, acidifying Mother Goose Lake from surface to depth (approximately 0.5 km 3 in volume at a pH of 2.9 to 3.1), killing all aquatic life, and preventing the annual salmon run. Over 2 months later, crater lake water sampled 8 km downstream of the outlet after considerable dilution from glacial meltwater was a weak sulfuric acid solution (pH = 3.2, SO 4 = 504 mg/L, Cl = 53.6 mg/L, and F = 7.92 mg/L). The acid flood waters caused severe vegetation damage, including plant death and leaf kill along the flood path. The crater lake drainage was accompanied by an ambioructic flow of acidic aerosols that followed the flood path, contributing to defoliation and necrotic leaf damage to vegetation in a 29 km 2 area along and above affected streams, in areas to heights of over 150 m above stream level. Moss species killed in the event contained high levels of sulfur, indicating extremely elevated atmospheric sulfurcontent. The most abundant airborne phytotoxic constituent was likely sulfuric acid aerosols that were generated during the catastrophic partial crater lake drainage event. Two mechanisms of acidic aerosol formation are proposed: (1) generation of aerosol mist through turbulent flow of acidic water and (2) catastrophic gas exsolution. This previously undocumented phenomenon of simultaneous vegetationdamaging acidic aerosols accompanying drainage of an acidic crater lake has important implications for the study of hazards associated with active volcanic crater lakes. Copyright 2008 by the American Geophysical Union.

Geochemistry, Geophysics, Geosystems↗