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USGS1987

Iowa ground-water quality

The population served by ground-water supplies in Iowa (fig. L4) is estimated to be about 2,392,000, or 82 percent of the total population (U.S. Geological Survey, 1985, p. 211). The population of Iowa is distributed fairly uniformly throughout the State (fig. IB), with 59 percent residing in rural areas or towns of less than 10,000 (U.S. Bureau of the Census, 1982). Surficial aquifers, the Jordan aquifer, and aquifers that form the uppermost bedrock aquifer in a particular area are most commonly used for drinking-water supplies and usually provide ample amounts of good quality water. However, naturally occurring properties or substances such as hardness, dissolved solids, and radioactivity limit the use of water for drinking purposes in some areas of each of the five principal aquifers (fig. 2/4). Median concentrations of nitrate in all aquifers and radium-226 in all aquifers except the Jordan are within the primary drinking-water standards established by the U.S. Environmental Protection Agency (1986a). Median concentrations for dissolved solids in the surficial, Dakota, and Jordan aquifers exceed secondary drinking-water standards established by the U.S. Environmental Protection Agency (1986b). Ground water in Iowa, however, has been affected by human induced contamination. Water from some wells in surficial and the uppermost bedrock aquifers contains nitrate concentrations exceeding the primary drinking-water standard of 10 mg/L (milligrams per liter) as nitrogen. Surficial aquifers also contain detectable concentrations of pesticides and other organic substances. Standards have not been established for many of the organic substances detected, and water supplies containing these substances may continue to be used. The long-term health consequences of exposure to these substances are not known; however, the estimated number of people in Iowa exposed to pesticide contaminants is believed to exceed 750,000 or 25 percent of the population (Kelley and others, 1986.) Land-use and waste-disposal practices are believed to be responsible for most human-induced contamination in Iowa. About 33 million acres, or nearly 93 percent of the land area of Iowa, is fanned (Skow and Halley, 1986). About 56 million pounds of herbicides was used for agriculture during 1979 (Becker and Stockdale, 1980) and about 2.7 million tons of fertilizer products was used during 1985 (Skow and Halley, 1986). Additionally, 30 hazardous-waste sites are under authority of the Federal Resource Conservation and Recovery Act (RCRA) of 1976; six other sites have been listed in the National Priorities List (NPL) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 (U.S. Environmental Protection Agency, 1986c). As of September 1985, two Federal sites at one facility under the U.S. Department of Defense Installation Restoration Program (IRP) were designated for remedial response in accordance with CERCLA. In addition to the above sites, Iowa has 90 active municipal landfills (fig. 3C). The U.S. Geological Survey, in cooperation with the University of Iowa Hygienic Laboratory, the Iowa Department of Natural Resources, and several counties in Iowa, currently (1986) is monitoring about 1,500 public and private wells for inorganic and organic constituents. The principal objective of this program, begun in 1982, is to collect water-quality data that will describe the long-term chemical quality of the surficial and major bedrock aquifer systems in Iowa (Detroy, 1985).

Iowa↗

USGS1983

Hydrologic and geomorphic studies of the Platte River basin

The channels of the Platte River and its major tributaries, the South Platte and North Platte Rivers in Colorado, Wyoming, and Nebraska, have undergone major changes in hydrologic regime and morphology since about 1860, when the water resources of the basin began to be developed for agricultural, municipal, and industrial uses. These water uses have continued to increase with growth in population and land development. Diversion of flow from channels, storage of water in reservoirs, and increased use of ground water have affected the distribution and timing of streamflows and the transport of fluvial sediments. All these factors have contributed to changes in channel geometry and the riverine environment. In 1979, the U.S. Geological Survey began investigations in the Platte River basin to determine the effects of water use on the hydrology and morphology of the Platte River and its major tributaries. These investigations also considered the relationship of hydrologic regime to factors that control or affect the habitat of migratory waterfowl in the Platte River valley. This volume brings together the results of several research studies on historical changes in channel morphology, surface-water hydrology, hydraulic geometry, sediment-transport and bedform processes, ground-water and surface-water relations, stochastic models of streamflow and precipitation, and methods for estimating discharge required to maintain channel width. In each of the studies, data on some segment of the Platte River hydrologic system were collected and interpreted. All the studies are interrelated; together they provide some degree of understanding of regime changes that are occurring. The hydrologic research described in the following chapters will be useful in decision-making pertaining to the management of water resources and migratory waterfowl habitats.

Colorado, Nebraska, Wyoming↗

USGS2006

Aspects of the biology of Salicornia bigelovii torr. In relation to a proposed restoration of a wind-tidal flat system on the South Texas, USA Coast

Wind-tidal flats are the dominant coastal wetland type in southern Texas USA. Succulent vascular plants are colonizing the flats in some locations, often where past dredge disposal along navigation channels and other activities have interrupted natural water communication between hypersaline bays and large areas of wind-tidal flats. The objective of this study was to test the feasibility of proposed removal of a causeway at Laguna Atascosa National Wildlife Refuge to restore the historic hydrologic regime and eradicate encroaching vascular plants, mostly Salicornia bigelovii, on the assumption that high sediment salt excluded these vascular plants under natural conditions. Assessment in spring 1998 of the density of Salicornia in relation to elevation and sediment salt of bare and vegetated zones on the vegetated flats on one side of the causeway and entirely barren flats with unimpaired connection to Laguna Madre on the other side of the causeway suggested that sediment salt >0.1 g ml-1 excluded vascular plants. However, bimonthly sampling in 1999-2000 revealed that sediment salt concentrations were >0.1 g ml-1 throughout the vegetated zone in July and more locally in the period of winter low water, with little impairment to established plants. This indicates that if control is desired, it must be exerted at germination and early establishment during and after fall high water. Continuous monitoring of water levels on either side of the causeway suggests that, even with removal of the causeway, flooding with hypersaline lagoon water will be too infrequent to counteract the freshening effect of a permanent hydraulic connection to the main agricultural drain of the lower Rio Grande Valley that has developed at the other end of the salt flat. Monitoring Salicornia distribution over six years documented huge variation between years but no trend toward increasing dominance of the flats. The results of this study illustrate that the most obvious alterations to a site may not be the most influential on function and that the scale of analysis may have to extend far beyond the site in space and time to evaluate a proposed restoration properly. ?? 2006, The Society of Wetland Scientists.

Wetlands↗

USGS2017

Using object-based image analysis to conduct high-resolution conifer extraction at regional spatial scales

The distribution and abundance of pinyon ( Pinus monophylla ) and juniper ( Juniperus osteosperma, J. occidentalis ) trees (hereinafter, "pinyon-juniper") in sagebrush ( Artemisia spp.) ecosystems of the Great Basin in the Western United States has increased substantially since the late 1800s. Distributional expansion and infill of pinyon-juniper into sagebrush ecosystems threatens the ecological function and economic viability of these ecosystems within the Great Basin, and is now a major contemporary challenge facing land and wildlife managers. Particularly, pinyon-juniper encroachment into intact sagebrush ecosystems has been identified as a primary threat facing populations of greater sage-grouse ( Centrocercus urophasianus ; hereinafter, "sage-grouse"), which is a sagebrush obligate species. Even seemingly innocuous scatterings of isolated pinyon-juniper in an otherwise intact sagebrush landscape can negatively affect survival and reproduction of sage-grouse. Therefore, accurate and high-resolution maps of pinyon-juniper distribution and abundance (indexed by canopy cover) across broad geographic extents would help guide land management decisions that better target areas for pinyon-juniper removal projects (for example, fuel reduction, habitat improvement for sage-grouse, and other sagebrush species) and facilitate science that further quantifies ecological effects of pinyon-juniper encroachment on sage-grouse populations and sagebrush ecosystem processes . Hence, we mapped pinyon-juniper (referred to as conifers for actual mapping) at a 1 × 1-meter (m) high resolution across the entire range of previously mapped sage-grouse habitat in Nevada and northeastern California. We used digital orthophoto quad tiles from National Agriculture Imagery Program (2010, 2013) as base imagery, and then classified conifers using automated feature extraction methodology with the program Feature Analyst ™ . This method relies on machine learning algorithms that extract features from imagery based on their spectral and spatial signatures. We classified conifers in 6,230 tiles and then tested for errors of omission and commission using confusion matrices. Accuracy ranged from 79.1 to 96.8, with an overall accuracy of 84.3 percent across all mapped areas. An estimated accuracy coefficient (kappa) indicated substantial to nearly perfect agreement, which varied across mapped areas. For this mapping process across the entire mapping extent, four sets of products are available at https://doi.org/10.5066/F7348HVC , including (1) a shapefile representing accuracy results linked to mapping subunits; (2) binary rasters representing conifer presence or absence at a 1 × 1 m resolution; (3) a 30 × 30 m resolution raster representing percentages of conifer canopy cover within each cell from 0 to 100; and (4) 1 × 1 m resolution canopy cover classification rasters derived from a 50-m-radius moving window analysis. The latter two products can be reclassified in a geographic information system (GIS) into user-specified bins to meet different objectives, which include approximations for phases of encroachment. These products complement, and in some cases improve upon, existing conifer maps in the Western United States, and will help facilitate sage-grouse habitat management and sagebrush ecosystem restoration.

California, Nevada↗

USGS1960

Ecological systems and the water resources

In ancient Sparta there were two principal classes of society, the citizen and the helot. The citizen was trained principally to be a warrior. The helot, a serf, was the tiller of the land but could be called to military duty. The history of Herodotus makes it amply clear that making war was the biggest business of the times. Because the Spartans were always marching off to war with someone, they found the landbound position of their city, located as its is in a small central basin nearly surrounded by mountains, somewhat of a disadvantage. When they were under attack, of course, this situation was a favorable one inasmuch as a seaborne enemy had to march inland to come to grips with the Lacedaemonians. The relatively small size of the independent states meant that the Spartans had no direct access through their own lands to the sea. There is evidence that the Spartans reached an agreement with surrounding states concerning a free corridor. There would be maintained by all the Grecian states of the Peloponnesus an access route stretching essentially from Sparta to Corinth, through which a marching army could have access to a seaport. As a secondary benefit, this no man's land, which in our western lingo might be called a stock driveway, allowed merchants and their caravans to move freely between the flourishing trading port of Corinth and the inland cities to the south and west. Apparently one portion of the agreement between the states with regard to the use of this access zone was that there should be no permanent agricultural or grazing in the driveway. As a result, through several centuries B.C. during which there was high population density in the Aegean area, one strip of land was exempted from the pressures of grazing, lumbering, and agriculture which characterized most of the rest of the landscape. Today this driveway maintains a forest cover. In contrast, mountainsides nearby with an even larger annual rainfall support hardly a tree. It is not entirely apparent why subsequent centuries did not see this area denuded. Even with the scanty details known to me it seems clear that the peculiar history of this one area potentially offers us a greater insight into some aspects of forest and land conditions of classical times than extant written records. The several references to sources of timber and cutting of forests contained in the vivid chronicle of Herodotus are valuable, but they lack species identification for the most part. Though rich in human understanding and psychological insight, his history strongly resembles the travel sagas of the Spanish Conquistadors of our Southwest, who had no real eye for "country." Even a careful reading of the works of early travelers such as Coronado, Garces, and Espejo, gives no picture of the nature of the country, its vegetation, or its rivers. To describe a biota there is no substitute for a sample. It is logical to ask what one might want to know which would require the preservation of a sample. Whether such a question is asked at all is a reflection on the stage of intellectual maturity of a civilization. We take for granted that there is social gain in the erection and maintenance of a museum of fine arts, a museum of natural history, or a historical museum. Sooner or later we should be mature enough to extend this concept to include a "museum" consisting of samples of land types as nearly as possible unaffected by man.

Circular↗

USGS2008

Flood of June 7-9, 2008, in Central and Southern Indiana

On June 6-7, 2008, heavy rainfall of 2 to more than 10 inches fell upon saturated soils and added to already high streamflows from a wetter than normal spring in central and southern Indiana. The heavy rainfall resulted in severe flooding on many streams within the White River Basin during June 7-9, causing three deaths, evacuation of thousands of residents, and hundreds of millions of dollars of damage to residences, businesses, infrastructure, and agricultural lands. In all, 39 Indiana counties were declared Federal disaster areas. U.S. Geological Survey (USGS) streamgages at nine locations recorded new record peak streamflows for the respective periods of record as a result of the heavy rainfall. Recurrence intervals of flood-peak streamflows were estimated to be greater than 100 years at five streamgages and 50-100 years at two streamgages. Peak-gage-height data, peak-streamflow data, and recurrence intervals are tabulated for 19 USGS streamgages in central and southern Indiana. Peak-streamflow estimates are tabulated for four ungaged locations, and estimated recurrence intervals are tabulated for three ungaged locations. The estimated recurrence interval for an ungaged location on Haw Creek in Columbus was greater than 100 years and for an ungaged location on Hurricane Creek in Franklin was 50-100 years. Because flooding was particularly severe in the communities of Columbus, Edinburgh, Franklin, Paragon, Seymour, Spencer, Martinsville, Newberry, and Worthington, high-water-mark data collected after the flood were tabulated for those communities. Flood peak inundation maps and water-surface profiles for selected streams were made in a geographic information system by combining the high-water-mark data with the highest-resolution digital elevation model data available.

Open-File Report↗

USGS2010

Investigation of submarine groundwater discharge along the tidal reach of the Caloosahatchee River, southwest Florida

The tidal reach of the Caloosahatchee River is an estuarine habitat that supports a diverse assemblage of biota including aquatic vegetation, shellfish, and finfish. The system has been highly modified by anthropogenic activity over the last 150 years (South Florida Water Management District (SFWMD), 2009). For example, the river was channelized and connected to Lake Okeechobee in 1881 (via canal C-43). Subsequently, three control structures (spillway and locks) were installed for flood protection (S-77 and S-78 in the 1930s) and for saltwater-intrusion prevention (S-79, W.P. Franklin Lock and Dam in 1966). The emplacement of these structures and their impact to natural water flow have been blamed for water-quality problems downstream within the estuary (Flaig and Capece, 1998; SFWMD, 2009). Doering and Chamberlain (1999) found that the operation of these control structures caused large and often rapid variations in salinity during various times of the year. Variable salinities could have deleterious impacts on the health of organisms in the Caloosahatchee River estuary. Flow restriction along the Caloosahatchee has also been linked to surface-water eutrophication problems (Doering and Chamberlain, 1999; SFWMD, 2009) and bottom-sediment contamination (Fernandez and others, 1999). Sources of nutrients (nitrogen and phosphorous) that cause eutrophication are primarily from residential sources and agriculture, though wastewater-treatment-plant discharges can also play a major role (SFWMD, 2009). The pathway for many of these nutrients is by land runoff and direct discharge from stormwater drains. An often overlooked source of nutrients and other chemical constituents is from submarine groundwater discharge (SGD). SGD can be either a diffuse or point source (for example, submarine springs) of nutrients and other chemical constituents to coastal waters (Valiela and others, 1990; Swarzenski and others, 2001; 2006; 2007; 2008). SGD can be composed of either fresh or marine water or various mixed ratios of fresh and marine water (Martin and others, 2007). In coastal areas where water-table elevations (hydraulic gradients) are steep, such as in Hood Canal, Washington (Swarzenski and others, 2007; Simonds and others, 2008), groundwater entering the coastal marine waters can be fresh (~1-4 parts per thousand, ppt). SGD in coastal locations that have low relief (low hydraulic gradients) such as the study area or other locations in Florida are typically driven by tidal pumping (Reich and others, 2002; 2008; Swarzenski and others, 2008), and water advecting into surface water is composed of recirculated marine water mixed with either fresh or brackish groundwaters. The importance of SGD in the delivery of nutrients and trace elements to coastal environments has been shown to be both beneficial and deleterious to ecosystem health (Valiela and others, 1990). The logical step in studying SGD is to map areas where SGD occurs. Methods such as continuous surface-water radon-222 ( 222 Rn) mapping and electrical resistivity (continuous resistivity profiles, CRP) have been developed and used to identify potential SGD sites (Dulaiova and others, 2005; Swarzenski and others 2004; 2006; 2007; 2008; Reich and others, 2008). CRP data record subsurface, bulk-resistivity measurements to depths up to 25 meters (m). The bulk resistivity can be representative of changes in porewater salinity or in lithology (Reich and others, 2008; Swarzenski and others, 2008). Radon-222 (half-life = 3.28 days) is a natural tracer of groundwater, because sediments and rocks, containing uranium-bearing materials such as limestone and phosphatic material, continually produce 222 Rn. Rn-222 (also referred to simply as radon) is an ideal tracer, because there is a constant source. Since radon is a gas, 222 Rn does not build up in the surface water but rather evades directly to the atmosphere (Burnett and Dulaiova, 2003; Burnett and others, 2003; Dulaiova and Burnett, 2006).

Florida↗

USGS2002

Llano Grande Lake bottom sediments; a chronicle of water-quality changes in the Arroyo Colorado, South Texas, 1989-2001

The Arroyo Colorado, an ancient channel of the Rio Grande, extends 90 miles from Mission, Tex., to the Laguna Madre. The Arroyo Colorado flows through areas of intense agricultural cultivation and through important habitat for migrating birds and other wildlife, including several wildlife sanctuaries and refuges. The above-tidal segment of the Arroyo Colorado is included in the State of Texas 2000 Clean Water Act 303(d)1 list in part because of elevated concentrations of the hydrophobic legacy pollutants DDE (a DDT breakdown product), chlordane, and toxaphene in fish tissue. This report addresses three questions: Do legacy pollutants (organochlorine compounds, major and trace elements) occur in the Arroyo Colorado at present and at what concentrations? How has the occurrence of selected legacy pollutants in the Arroyo Colorado changed over time? Are current concentrations of legacy pollutants in bottom sediments at levels of concern for the health of aquatic biota? To answer these questions, the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (USEPA), collected and analyzed a sediment core from Llano Grande Lake on the Arroyo Colorado (fig. 1). Sediment cores can be used to reconstruct historical trends in concentrations of hydrophobic contaminants (Eisenreich and others, 1989; Van Metre and others, 1997, 2000). The lake is part of the Rio Grande delta drainage system (fig. 1). The lake is 6 miles long and has a maximum width of 600 feet.

Texas↗

USGS2002

The Sparta Aquifer: A Sustainable Water Resource?

Introduction The Sparta aquifer is an aquifer of regional importance within the Mississippi embayment aquifer system. It consists of varying amounts of unconsolidated sand, inter-stratified with silt and clay lenses within the Sparta Sand of the Claiborne Group. It extends from south Texas, north into Louisiana, Arkansas, and Tennessee, and eastward into Mississippi and Alabama (fig. 1). On both the west and east sides of the Mississippi embayment, the Sparta aquifer is exposed at the surface (outcrops) and is locally unconfined; it becomes confined as it dips toward the axis of the embayment, (generally corresponding with the Mississippi River) and southward toward the Gulf of Mexico where it is deeply buried in the subsurface (Hosman, 1968). Generalized ground-water flow in the Sparta aquifer is from the outcrop areas to the axis (center) of the embayment (fig. 2). In Arkansas, the Sparta aquifer outcrops parallel to the Fall Line at the western extreme of the Mississippi embayment (the Fall Line is a line dividing the mountainous highlands of Arkansas from the lowland area); and the formation dips from its outcrop area to the southeast. The Sparta aquifer supplies water for municipalities, industries such as paper production, and to a lesser degree, irrigation of agricultural crops (fig. 3). This report highlights hydrologic conditions of the aquifer in Arkansas County as an example of how water use is affecting water levels.

Fact Sheet↗

USGS2016

Users and uses of Landsat 8 satellite imagery—2014 survey results

Executive Summary In 2013, Landsat 8 began adding high quality, global, moderate-resolution imagery to the more than 40-year archive of Landsat imagery. To assess the potential effects of the availability of Landsat 8 imagery on users and their work, the U.S. Geological Survey (USGS) Land Remote Sensing Program (LRS) initiated a survey of Landsat users. The objectives of the survey were to 1. Characterize various Landsat user groups, such as United States (U.S.) and international users and Landsat 8 and non-Landsat 8 users; 2. Identify any differences among user groups in uses and preferences; 3. Measure the importance of and satisfaction with Landsat 8 attributes; 4. Assess the importance to users of the frequency of usable imagery; and 5. Determine any challenges in using Landsat 8. The online survey was sent to 51,617 Landsat users registered with USGS in May 2014. Almost 13,000 people responded to the survey for a response rate of 25 percent (n = 12,966). Current Landsat users (users who had used Landsat in their work in the year prior to the survey) composed 89 percent of the sample (n = 11,549) and past Landsat users composed 11 percent (n = 1,417). The results reported here apply to current Landsat users registered with the USGS Earth Resources Observation and Science (EROS) Center. Users from 161 countries responded to the survey. Of those, 19 percent were citizens or permanent residents of the United States and 81 percent resided in other countries. More than 70 percent of current users had used Landsat 8 in the year prior to the survey. The majority of Landsat 8 users (65 percent) were established users who used Landsat imagery regularly both before and after Landsat 8 imagery became available. The average current Landsat user was male, 36 years old, and highly educated, with 9 years of experience using satellite imagery or geographic information system (GIS) software. Landsat 8 users had, on average, two more years of experience than non-Landsat 8 users. Users were employed predominantly by academic institutions (65 percent), followed by private businesses (13 percent), Federal governments (10 percent), State and local governments (6 percent), and nonprofit organizations (6 percent). Of the Landsat imagery obtained in the past year by current users, on average 31 percent came from a Landsat 8 sensor. An equivalent amount came from the Landsat 7 ETM+ sensor (33 percent); slightly less came from Landsats 4 and 5 TM sensors (27 percent). Much less came from Landsats 1 through 5 MSS sensors (5 percent). Overall, more than a third of users’ work used Landsat imagery (38 percent). Of this work, on average, 37 percent of the work was operational. Landsat 8 users considered a greater proportion of their work operational than non-Landsat 8 users (39 percent compared with 29 percent). Environmental sciences and management were the most commonly selected primary applications (selected by 42 percent of users). Land use/land cover (23 percent) was the second most commonly selected primary application, followed by education (12 percent), agriculture (9 percent), and planning and development (6 percent). Landsat 8 users were asked to rank the importance of certain attributes in determining whether to use Landsat 8 imagery in their work. The archive was ranked most important, followed by cost, spatial resolution, extent of coverage, data quality, and frequency of revisit. Users were asked how satisfied they were with these same attributes as they currently apply to Landsat 8 imagery. On average, users were most satisfied with lack of cost, extent of coverage, data quality, and the archive, but they were satisfied with all attributes. Users were asked how often they needed Landsat imagery to meet various requirements for their primary application. The survey question specifically asked how often users needed usable imagery, which differs from how often they would like the Landsat satellites to acquire an image. Users were asked to identify their needed frequency of usable imagery for the following levels: 1. Threshold level—the minimum frequency of usable imagery needed to be of any value to their primary application. 2. Breakthrough level—the frequency of usable imagery that would result in a significant improvement for their primary application of the imagery. 3. Target level—the frequency of usable imagery that would only provide a limited additional increase in the expected performance for their primary application. To meet the threshold level, three-quarters of users needed usable imagery every 17 days or less frequently. At the breakthrough level, two-thirds of users (64 percent) needed a usable image every 5–16 days. The current constellation of two satellites (Landsat 7 and 8) is capable of meeting the threshold and breakthrough needs of most users at least some of the time, but a single satellite would be highly unlikely to do so. Two-fifths of users (40 percent) felt that usable imagery provided every 4 days or more frequently would meet their target level which the current Landsat constellation cannot provide. Landsat 8 users were significantly more likely than non-Landsat 8 users to need usable imagery more frequently to meet their target levels. Additionally, U.S. Landsat 8 users were significantly more likely than other Landsat users to need usable imagery more frequently in order meet both their breakthrough and target levels. To explore the effect of the availability of Landsat 8 imagery on Landsat imagery use in general, established users (those who had consistently used Landsat imagery both before and after Landsat 8 imagery became available) using Landsat 8 imagery were asked about changes in the amount of Landsat imagery they used. The majority of established users using Landsat 8 imagery (60 percent) reported an average increase of 51 percent in the number of scenes obtained after Landsat 8 imagery became available. Landsat 8 users were asked if they had encountered challenges in using Landsat 8 whereas non-Landsat 8 users were asked if such challenges had played a role in why they were not using Landsat 8 imagery. Although many users did not encounter challenges when using or trying to use Landsat 8 data, slightly less than 30 percent did encounter issues with processing the data to a usable point. The most common issue reported was not being able to create or have access to a surface reflectance corrected product. Other challenges were related to the file sizes of images being too large to download, store, or analyze. There were no statistically significant differences between Landsat 8 and non-Landsat 8 users in terms of challenges encountered when using or trying to use the imagery, which indicates that users were not unduly discouraged by the challenges they may have encountered. When asked about potential consequences of not using Landsat 8, more than half of the non-Landsat 8 users did not report detrimental effects on their work from not using the imagery. Of those who did report detrimental effects, decreased quality of work, decreased scope of work, and increased time spent on work were the most common.

Open-File Report↗

USGS2000

Seagrass responses to and recovery (?) from seven years of brown tide

Most harmful algal blooms are relatively short, violent paroxysms to aquatic systems. The Texas brown tide was unique in its 7-year domination of upper Laguna Madre wherein it reduced light penetrating 1 m from 31 to 63% on an annual basis between June 1990 and May 1997. In response, seagrasses declined in biomass in deep areas for two years. Over the next three years, bare areas opened up in the deepest areas of the seagrass meadow and the outer seagrass boundary retreated landward. In the last two years of the brown tide, regression of the dominant species, Halodule wrightii, slowed and stopped, and Halophila engelmanni, a previously minor species, revegetated some areas. Subsequent to cessation of meadow retreat, water clarity improved to pre-brown tide levels, consistent with the hypothesis that regeneration of nutrients from retreating seagrass meadow may have been the source of the nutrient subsidy required to sustain the brown tide at high concentration. However, after a short interlude of clear water and Halodule recovery, a resurgence of the bloom occurred and areas of regrowth succumbed. Although human activities did not seem to be involved in initiation or persistence of the brown tide, nutrients brought in by runoff from agricultural lands may have contributed to the return of bloom conditions.

Texas↗

USGS2007

Setting an effective TMDL: Sediment loading and effects of suspended sediment on fish

The Agricultural Drainage and Pesticide Transport model was used to examine the relationship between fish and suspended sediment in the context of a proposed total maximum daily load ( TMDL ) in two agricultural watersheds in Minnesota. During a 50-year simulation, Wells Creek, a third-order cold water stream, had an estimated 1,164 events (i.e., one or more consecutive days of estimated sediment loading ) and the Chippewa River, a fourth-order warm water stream, had 906 events of measurable suspended sediment . Sublethal thresholds were exceeded for 970 events and lethal levels for 194 events for brown trout in Wells Creek, whereas adult nonsalmonidis would have experienced sublethal levels for 923 events and lethal levels for 241 events. Sublethal levels were exceeded for 756 events and lethal thresholds were exceeded for 150 events in the Chippewa River. Nonsalmonids would have experienced 15 events of mortality between 0 and 20 percent in Wells Creek. In the Chippewa River, there were 35 events of mortality between 0 and 20 percent and one event in which mortality could have exceeded 20 percent. The Minnesota Pollution Control Agency has proposed listing stream reaches as being impaired for turbidity at 25 NTU, which is approximately 46 mg suspended sediment /l. We estimated that 46 mg/l would be exceeded approximately 30 days in a year (d/yr) in both systems. A TMDL of 46 mg SS/l may be too high to ensure that stream fishes are not negatively affected by suspended sediment . We recommend that an indicator incorporating the duration of exposure be applied.

Journal of the American Water Resources Associatio↗

USGS2008

Factors Affecting Nitrate Delivery to Streams from Shallow Ground Water in the North Carolina Coastal Plain

An analysis of data collected at five flow-path study sites between 1997 and 2006 was performed to identify the factors needed to formulate a comprehensive program, with a focus on nitrogen, for protecting ground water and surface water in the North Carolina Coastal Plain. Water-quality protection in the Coastal Plain requires the identification of factors that affect the transport of nutrients from recharge areas to streams through the shallow ground-water system. Some basins process or retain nitrogen more readily than others, and the factors that affect nitrogen processing and retention were the focus of this investigation to improve nutrient management in Coastal Plain streams and to reduce nutrient loads to coastal waters. Nitrate reduction in ground water was observed at all five flow-path study sites in the North Carolina Coastal Plain, although the extent of reduction at each site was influenced by various environmental, hydrogeologic, and geochemical factors. Denitrification was the most common factor responsible for decreases in nitrate along the ground-water flow paths. Specific factors, some of which affect denitrification rates, that appeared to influence ground-water nitrate concentrations along the flow paths or in the streams include soil drainage, presence or absence of riparian buffers, evapotranspiration, fertilizer use, ground-water recharge rates and residence times, aquifer properties, subsurface tile drainage, sources and amounts of organic matter, and hyporheic processes. The study data indicate that the nitrate-reducing capacity of the buffer zone combined with that of the hyporheic zone can substantially lower the amount of ground-water nitrate discharged to streams in agricultural settings of the North Carolina Coastal Plain. At the watershed scale, the effects of ground-water discharge on surface-water quality appear to be greatly influenced by streamflow conditions and the presence of extensive riparian vegetation. Streamflow statistics that reflect base flow and the general hydrologic dynamics of a stream are important in understanding nutrient transport from a watershed and may be useful indicators of watersheds that are likely to have higher yields of nutrients and water. Combining streamflow statistics with information on such factors as land use, soil drainage, extent of riparian vegetation, geochemical conditions, and subsurface tile drainage in the Coastal Plain can be useful in identifying watersheds that are most likely to export excessive nitrogen due to nonpoint-source loadings and watersheds that are effective in processing nitrogen.

North Carolina↗

USGS2017

Unusual population attributes of invasive red-eared slider turtles ( Trachemys scripta elegans ) in Japan: do they have a performance advantage?

The slider turtle ( Trachemys scripta Thunberg in Schoepff, 1792) is native to the USA and Mexico. Due to the popularity of their colorful hatchlings as pets, they have been exported worldwide and are now present on all continents, except Antarctica. Slider turtles are well-established in Japan and occupy aquatic habitats in urban and agricultural areas, to the detriment of native turtles with which they compete. We asked the overall question, do slider turtles in Japan have a performance advantage because they are liberated from the numerous competing turtle species in their native range and released from many of their natural predators? Traits compared included various measures of adult body size (mean, maximum), female size at maturity as measured by size of gravid females, clutch size, population density and biomass, sex ratio, and sexual size dimorphism, the latter two a partial reflection of growth and maturity differences between the sexes. We sampled slider turtle populations in three habitats in Japan and compared population attributes with published data for the species from throughout its native range in the USA. Mean male body sizes were at the lower end of values from the USA suggesting that males in Japan may mature at smaller body sizes. The smallest gravid females in Japan mature at smaller body sizes but have mean clutch sizes larger than some populations in the USA. Compared to most populations in the USA, slider turtles achieve higher densities and biomasses in Japanese wetlands, especially the lotic system we sampled. Sex ratios were female-biased, the opposite of what is reported for many populations in protected areas of the USA. Sexual size dimorphism was enhanced relative to native populations with females as the larger sex. The enhanced dimorphism is likely a result of earlier size of maturity in Japanese males and the large size of mature (gravid) Japanese females. Slider turtles appear to have a performance advantage over native turtles in Japan, possibly as a result of being released from competition with numerous sympatric turtle species in their native range, and the absence of many co-evolved predators and parasites in Japan. This slight competitive edge, coupled with the catholic diet and broad tolerance of varying aquatic habitats of slider turtles, is reflected in their dominance over native and naturalized Japanese turtles in altered aquatic habitats.

Aquatic Invasions↗

USGS2008

Tile drainage as karst: Conduit flow and diffuse flow in a tile-drained watershed

The similarity of tiled-drained watersheds to karst drainage basins can be used to improve understanding of watershed-scale nutrient losses from subsurface tile drainage networks. In this study, short-term variations in discharge and chemistry were examined from a tile outlet collecting subsurface tile flow from a 963 ha agricultural watershed. Study objectives were to apply analytical techniques from karst springs to tile discharge to evaluate water sources and estimate the loads of agricultural pollutants discharged from the tile with conduit, intermediate and diffuse flow regimes. A two-member mixing model using nitrate, chloride and specific conductance was used to distinguish rainwater versus groundwater inputs. Results indicated that groundwater comprised 75% of the discharge for a three-day storm period and rainwater was primarily concentrated during the hydrograph peak. A contrasting pattern of solute concentrations and export loads was observed in tile flow. During base flow periods, tile flow consisted of diffuse flow from groundwater sources and contained elevated levels of nitrate, chloride and specific conductance. During storm events, suspended solids and pollutants adhered to soil surfaces (phosphorus, ammonium and organic nitrogen) were concentrated and discharged during the rapid, conduit flow portion of the hydrograph. During a three-day period, conduit flow occurred for 5.6% of the time but accounted for 16.5% of the total flow. Nitrate and chloride were delivered primarily with diffuse flow (more than 70%), whereas 80-94% of total suspended sediment, phosphorus and ammonium were exported with conduit and intermediate flow regimes. Understanding the water sources contributing to tile drainage and the manner by which pollutant discharge occurs from these systems (conduit, intermediate or diffuse flow) may be useful for designing, implementing and evaluating non-point source reduction strategies in tile-drained landscapes. ?? 2007 Elsevier B.V. All rights reserved.

Journal of Hydrology↗

USGS2014

A precipitation-runoff model for simulating natural streamflow conditions in the Smith River watershed, Montana, water years 1996-2008

This report documents the construction of a precipitation-runoff model for simulating natural streamflow in the Smith River watershed, Montana. This Precipitation-Runoff Modeling System model, constructed in cooperation with the Meagher County Conservation District, can be used to examine the general hydrologic framework of the Smith River watershed, including quantification of precipitation, evapotranspiration, and streamflow; partitioning of streamflow between surface runoff and subsurface flow; and quantifying contributions to streamflow from several parts of the watershed. The model was constructed by using spatial datasets describing watershed topography, the streams, and the hydrologic characteristics of the basin soils and vegetation. Time-series data (daily total precipitation, and daily minimum and maximum temperature) were input to the model to simulate daily streamflow. The model was calibrated for water years 2002–2007 and evaluated for water years 1996–2001. Though water year 2008 was included in the study period to evaluate water-budget components, calibration and evaluation data were unavailable for that year. During the calibration and evaluation periods, simulated-natural flow values were compared to reconstructed-natural streamflow data. These reconstructed-natural streamflow data were calculated by adding Bureau of Reclamation’s depletions data to the observed streamflows. Reconstructed-natural streamflows represent estimates of streamflows for water years 1996–2007 assuming there was no agricultural water-resources development in the watershed. Additional calibration targets were basin mean monthly solar radiation and potential evapotranspiration. The model estimated the hydrologic processes in the Smith River watershed during the calibration and evaluation periods. Simulated-natural mean annual and mean monthly flows generally were the same or higher than the reconstructed-natural streamflow values during the calibration period, whereas they were lower during the evaluation period. The shape of the annual hydrographs for the simulated-natural daily streamflow values matched the shape of the hydrographs for the reconstructed-natural values for most of the calibration period, but daily streamflow values were underestimated during the evaluation period for water years 1996–1998. The model enabled a detailed evaluation of the components of the water budget within the Smith River watershed during the water year 1996–2008 study period. During this study period, simulated mean annual precipitation across the Smith River watershed was 16 inches, out of which 14 inches evaporated or transpired and 2 inches left the basin as streamflow. Per the precipitation-runoff model simulations, during most of the year, surface runoff rarely (less than 2 percent of the time during water years 2002–2008) makes up more than 10 percent of the total streamflow. Subsurface flow (the combination of interflow and groundwater flow) makes up most of the total streamflow (99 or more percent of total streamflow for 71 percent of the time during water years 2002–2008).

Montana↗

USGS2018

Quaternary sediment thickness and bedrock topography of the glaciated United States east of the Rocky Mountains

Beginning roughly 2.6 million years ago, global climate entered a cooling phase known as the Pleistocene Epoch. As snow in northern latitudes compacted into ice several kilometers thick, it flowed as glaciers southward across the North American continent. These glaciers extended across the northern United States, dramatically altering the landscape they covered. East of the Rocky Mountains, the ice coalesced into continental glaciers (called the Laurentide Ice Sheet) that at times blanketed much of the north-central and northeastern United States. To the west of the Laurentide Ice Sheet, glaciers formed in the mountains of western Canada and the United States and coalesced into the Cordilleran ice sheet; this relatively smaller ice mass extended into the conterminous United States in the northernmost areas of western Montana, Idaho, and Washington. Throughout the Pleistocene, landscape alteration occurred by (1) glacial erosion of the rocks and sediments; (2) redeposition of the eroded earth materials in a form substantially different from their source rocks, in terms of texture and overall character; and (3) disruption of preexisting drainage patterns by the newly deposited sediments. In many cases, pre-glacial drainage systems (including, for example, the Mississippi River) were rerouted because their older drainage courses became blocked with glacial sediment. The continental glaciers advanced and retreated many times across those areas. During each ice advance, or glaciation, erosion and deposition occurred, and the landscape was again altered. Through successive glaciations, the landscape and the bedrock surface gradually came to resemble their present configurations. As continental ice sheets receded and the Pleistocene ended, erosion and deposition of sediment (for example in stream valleys) continued to shape the landscape up to the present day (albeit to a lesser extent than during glaciation). The interval of time since the last recession of the glaciers is called the Holocene and, together with the Pleistocene, constitutes the Quaternary Period of geologic time; this publication characterizes the three-dimensional geometry of the Quaternary sediments and the bedrock surface that lies beneath. The pre-glacial landscape was underlain mostly by weathered bedrock generally similar in nature to that found in many areas of the non-glaciated United States. Glacial erosion and redeposition of earth materials produced a young, mineral-rich soil that formed the basis for the highly productive agricultural economy in the U.S. midcontinent. Extensive buried sands and gravels within the glacial deposits also provided a stimulus to other economic sectors by serving as high-quality aquifers supplying groundwater to the region’s industry and cities. An understanding of the three-dimensional distribution of these glacial sediments has direct utility for addressing various societal issues including groundwater quality and supply, and landscape and soil response to earthquake-induced shaking. The Quaternary sediment thickness map and bedrock topographic map shown here provide a regional overview and are intended to supplement the more detailed work on which they are based. Detailed mapping is particularly useful in populated areas for site-specific planning. In contrast, regional maps such as these serve to place local, detailed mapping in context; to permit the extrapolation of data into unmapped areas; and to depict large-scale regional geologic features and patterns that are beyond the scope of local, detailed mapping. They also can enhance the reader’s general understanding of the region’s landscape and geologic history and provide a source of information for regional decision making that could benefit by improved predictability of bedrock depth beneath the unconsolidated Quaternary sediments. To enable these maps to be analyzed in conjunction with other types of information, this publication also includes the map data in GIS compatible format.

Scientific Investigations Map↗

USGS1991

Hydrogeology and water quality of glacial-drift aquifers in the Bemidji-Bagley area, Beltrami, Clearwater, Cass, and Hubbard Counties, Minnesota

Unconfined and the upper confined aquifers in glacial drift are the primary sources of water in a 1,600 square-mile area including parts of Beltrami, Cass, Clearwater, and Hubbard Counties, Minnesota. The unconfineddrift aquifer consists of coarse sand and gravel in the center of the study area. The total area underlain by the unconfined-drift aquifer is approximately 550 square miles. The unconfined aquifer ranges in thickness from 0 to 130 feet, and is greater than 20 feet thick over an area of 280 square miles. On the basis of scant data, the transmissivity of the unconfined aquifer ranges from less than 70 feet squared per day in the south and west to greater than 8,900 feet squared per day in an area west of Bemidji. Well yields from 10 to 300 gallons per minute are possible in some areas. The unconfined and upper confined-drift aquifers are separated by a fine-grained confining unit of till or lake deposits. The thickness of the upper confined-drift aquifer ranges from 0 to 60 feet in the Bemidji area. On the basis of specific-capacity and aquifer-thickness data, and results of model simulations, the transmissivity of the upper confined-drift aquifer ranges from less than 100 feet squared per day in the south and west parts of the aquifer to about 12,800 feet squared per day in the area around Bemidji. Well yields of 10 to 2,100 gallons per minute are possible in some areas. The direction of ground-water flow in both unconfined and upper confineddrift aquifers is toward the Mississippi and Clearwater Rivers. These rivers are the major discharge points for both aquifers. Ground-water divides, which separate the ground-water flow systems that discharge to these rivers, are approximately coincidental with surface-water divides between the rivers. Water from both aquifers generally is of the calcium bicarbonate type and is very hard, averaging 309 and 267 milligrams per liter as CaCO 3 from confined and unconfined-drift aquifers, respectively. Water from both aquifers generally is suitable for drinking, crop irrigation, and most other uses. Concentrations of ammonia, boron, chromium, iron, manganese, and phenols, however, locally exceed recommended limits for drinking water (Minnesota Pollution Control Agency, 1988). Longer residence time and leakage through glacial till is believed to cause higher concentrations of common inorganic constituents in water from confined-drift aquifers than concentrations in water from the unconfined-drift aquifer. Elevated concentrations of nutrients, chloride, and phenols in the unconfined-drift aquifer may be related to land-use practices. Statistical comparisons of common chemical constituents in water from wells completed in the unconfined-drift aquifer in several land-use areas suggest that concentrations of many constituents and physical properties are generally greater for wells in areas of commercial and residential land-use than for wells in areas of agriculture or forest land-use. These constituents include ammonia plus organic nitrogen, phosphorus, calcium, sodium, potassium, chloride, sulfate, silica, dissolved solids, and specific conductances. The mean values of ammonia nitrogen, magnesium, and fluoride are generally greater for wells in commercial land-use type areas than for wells in forested and agricultural land-use type areas. The mean concentration of nitrogen (N0 2 + NO 3 , dissolved) is generally greater for wells in residential land-use type areas than for wells in forested and agricultural land-use type areas. The Kruskil-Wallis test, a nonparametric that for 12 of the 21 constituents sampled in groups in the unconfined-drift aquifer, a of these constituents and land use was found statistical technique, indicated common in all land-use type relation between the concentration to be statistically significant.

Minnesota↗