Laura Medalie
Science and Products
Quality of pesticide data for groundwater analyzed for the National Water-Quality Assessment Project, 2013–18
The National Water-Quality Assessment (NAWQA) Project of the U.S. Geological Survey (USGS) submitted nearly 1,900 samples collected from groundwater sites across the United States in 2013–18 for analysis of 225 pesticide compounds (pesticides and pesticide degradates, hereafter referred to as “pesticides”) by USGS National Water Quality Laboratory...
Bexfield, Laura M.; Belitz, Kenneth; Sandstrom, Mark W.; Beaty, Delicia; Medalie, Laura; Lindsey, Bruce D.; Nowell, Lisa H.
Influence of land use and region on glyphosate and aminomethylphosphonic acid in streams in the USA
Glyphosate is the most widely used herbicide in the United States for agricultural and non-agricultural weed control. Many studies demonstrate possible effects of glyphosate and its degradate AMPA on human and ecological health. Although glyphosate is thought to have limited mobility in soil, it is found year-round in many rivers and streams...
Medalie, Laura; Baker, Nancy T.; Shoda, Megan E.; Stone, Wesley W.; Meyer, Michael T.; Stets, Edward G.; Wilson, Michaelah C.
Use of Set Blanks in Reporting Pesticide Results at the U.S. Geological Survey National Water Quality Laboratory, 2001–15
Executive SummaryBackground.—Pesticide results from the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) are used for water-quality assessments by many agencies and organizations. The USGS is committed to providing data of the highest possible quality to the consumers of its data. A cooperator’s inquiries about specific...
Medalie, Laura; Sandstrom, Mark W.; Toccalino, Patricia L.; Foreman, William T.; ReVello, Rhiannon C.; Bexfield, Laura M.; Riskin, Melissa L. Estimating the high-arsenic domestic-well population in the conterminous United States
Arsenic concentrations from 20 450 domestic wells in the U.S. were used to develop a logistic regression model of the probability of having arsenic >10 μg/L (“high arsenic”), which is presented at the county, state, and national scales. Variables representing geologic sources, geochemical, hydrologic, and physical features were among the...
Ayotte, Joseph D.; Medalie, Laura; Qi, Sharon L.; Backer, Lorraine C.; Nolan, Bernard T.
Nutrient and pesticide contamination bias estimated from field blanks collected at surface-water sites in U.S. Geological Survey Water-Quality Networks, 2002–12
Potential contamination bias was estimated for 8 nutrient analytes and 40 pesticides in stream water collected by the U.S. Geological Survey at 147 stream sites from across the United States, and representing a variety of hydrologic conditions and site types, for water years 2002–12. This study updates previous U.S. Geological Survey evaluations...
Medalie, Laura; Martin, Jeffrey D.
Concentration, flux, and trend estimates with uncertainty for nutrients, chloride, and total suspended solids in tributaries of Lake Champlain, 1990–2014
The U.S. Geological Survey, in cooperation with the New England Interstate Water Pollution Control Commission and the Vermont Department of Environmental Conservation, estimated daily and 9-month concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids from 1990 (or first available date)...
Medalie, Laura
Use of acoustic backscatter to estimate continuous suspended sediment and phosphorus concentrations in the Barton River, northern Vermont, 2010-2013
The U.S. Geological Survey, in cooperation with the Vermont Department of Environmental Conservation, investigated the use of acoustic backscatter to estimate concentrations of suspended sediment and total phosphorus at the Barton River near Coventry, Vermont. The hypothesis was that acoustic backscatter—the reflection of sound waves off objects...
Medalie, Laura; Chalmers, Ann T.; Kiah, Richard G.; Copans, Benjamin
Concentration and flux of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids for monitored tributaries of Lake Champlain, 1990-2012
Annual and daily concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids were estimated for 18 monitored tributaries to Lake Champlain by using the Weighted Regressions on Time, Discharge, and Seasons regression model. Estimates were made for 21 or 23 years, depending on data availability,...
Medalie, Laura
High-water marks from tropical storm Irene for selected river reaches in northwestern Massachusetts, August 2011
A Presidential Disaster Declaration was issued for Massachusetts, with a focus on the northwestern counties, following flooding from tropical storm Irene on August 28–29, 2011. Three to 10 inches of rain fell during the storm on soils that were susceptible to flash flooding because of wet antecedent conditions. The gage height at one U.S....
Bent, Gardner C.; Medalie, Laura; Nielsen, Martha G.
Concentration, flux, and the analysis of trends of total and dissolved phosphorus, total nitrogen, and chloride in 18 tributaries to Lake Champlain, Vermont and New York, 1990–2011
Annual concentration, flux, and yield for total phosphorus, dissolved phosphorus, total nitrogen, and chloride for 18 tributaries to Lake Champlain were estimated for 1990 through 2011 using a weighted regression method based on time, tributary streamflows (discharges), and seasonal factors. The weighted regression method generated two series of...
Medalie, Laura
High-water marks from flooding in Lake Champlain from April through June 2011 and Tropical Storm Irene in August 2011 in Vermont
The U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency, identified high-water marks after two floods in Vermont during 2011. Following a snowy winter, new monthly precipitation records were set in Burlington, Vermont, in April and May 2011, causing extensive flooding from April through June. The spring 2011...
Medalie, Laura; Olson, S.A.
Concentrations of chloride and sodium in groundwater in New Hampshire from 1960 through 2011
Several studies from the 1970s and more recently (for example, Hall (1975), Daley and others (2009) and Mullaney (2009)) have found that concentrations of chloride and sodium in groundwater in New Hampshire have increased during the past 50 years. Increases likely are related to road salt and other anthropogenic sources, such as septic systems,...
Medalie, Laura
Herbicide glyphosate prevalent in U.S. streams and rivers
The herbicide glyphosate was detected at least once in 66 of 70 U.S. streams and rivers located in a range of land-use settings, according to a recent study by the U.S. Geological Survey National Water Quality Program. Glyphosate is the active ingredient in the popular weed killer Roundup® and is the most widely used herbicide in...
USGS National Water Quality Laboratory protocols effective at minimizing false-positive pesticide results
A new analysis of USGS National Water Quality Laboratory (NWQL) quality-control protocols finds that “false-positive” and “false negative” results—reporting that a compound is present in a sample when it is not or that a compound is not present when it is—are minimal.