Megan Shoda
Science and Products
Water-quality trends in U.S. rivers, 2002 to 2012: Relations to levels of concern
Effective management and protection of water resources relies upon understanding how water-quality conditions are changing over time. Water-quality trends for ammonia, chloride, nitrate, sulfate, total dissolved solids (TDS), total nitrogen (TN) and total phosphorus (TP) were assessed at 762 sites located in the conterminous United...
Shoda, Megan E.; Sprague, Lori A.; Murphy, Jennifer C.; Riskin, Melissa L.
Data analysis considerations for pesticides determined by National Water Quality Laboratory schedule 2437
In 2013, the U.S. Geological Survey National Water Quality Laboratory (NWQL) made a new method available for the analysis of pesticides in filtered water samples: laboratory schedule 2437. Schedule 2437 is an improvement on previous analytical methods because it determines the concentrations of 225 fungicides, herbicides, insecticides, and...
Shoda, Megan E.; Nowell, Lisa H.; Stone, Wesley W.; Sandstrom, Mark W.; Bexfield, Laura M. Complex mixtures of dissolved pesticides show potential aquatic toxicity in a synoptic study of Midwestern U.S. streams
Aquatic organisms in streams are exposed to pesticide mixtures that vary in composition over time in response to changes in flow conditions, pesticide inputs to the stream, and pesticide fate and degradation within the stream. To characterize mixtures of dissolved-phase pesticides and degradates in Midwestern streams, a synoptic study was...
Nowell, Lisa H.; Moran, Patrick W.; Schmidt, Travis S.; Norman, Julia E.; Nakagaki, Naomi; Shoda, Megan E.; Mahler, Barbara J.; Van Metre, Peter C.; Stone, Wesley W.; Sandstrom, Mark W.; Hladik, Michelle L. Recovery data for surface water, groundwater and lab reagent samples analyzed by the USGS National Water Quality Laboratory schedule 2437, water years 2013-15
Analytical recovery is the concentration of an analyte measured in a water-quality sample expressed as a percentage of the known concentration added to the sample (Mueller and others, 2015). Analytical recovery (hereafter referred to as “recovery”) can be used to understand method bias and variability and to assess the temporal changes in a method...
Shoda, Megan E.; Nowell, Lisa H.; Bexfield, Laura M.; Sandstrom, Mark W.; Stone, Wesley W. Prediction of pesticide toxicity in Midwest streams
The occurrence of pesticide mixtures is common in stream waters of the United States, and the impact of multiple compounds on aquatic organisms is not well understood. Watershed Regressions for Pesticides (WARP) models were developed to predict Pesticide Toxicity Index (PTI) values in unmonitored streams in the Midwest and are referred to as WARP-...
Shoda, Megan E.; Stone, Wesley W.; Nowell, Lisa H.
Real-time, continuous water-quality monitoring in Indiana and Kentucky
Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Indiana and Kentucky. A super gage includes streamflow and water-quality instrumentation and...
Shoda, Megan E.; Lathrop, Timothy R.; Risch, Martin R.
A summary of the benthic-invertebrate and fish-community data from streams in the Indianapolis metropolitan area, Indiana, 1981-2012
Intermittently, during 1981–2012, the U.S. Geological Survey sampled sites in the White River and several tributaries in the Indianapolis metropolitan area of Indiana for benthic invertebrates and fish communities. During 1981–87, one study focused on benthic-invertebrate data collection at three sites along the White River. During...
Voelker, David C.; Bunch, Aubrey R.; Dobrowolski, Edward G.; Shoda, Megan E.
Identifying nutrient reference sites in nutrient-enriched regions-Using algal, invertebrate, and fish-community measures to identify stressor-breakpoint thresholds in Indiana rivers and streams, 2005-9
Excess nutrients in aquatic ecosystems can lead to shifts in species composition, reduced dissolved oxygen concentrations, fish kills, and toxic algal blooms. In this study, nutrients, periphyton chlorophyll a (CHLa), and invertebrate- and fishcommunity data collected during 2005-9 were analyzed from 318 sites on Indiana rivers and streams. The...
Caskey, Brian J.; Bunch, Aubrey R.; Shoda, Megan E.; Frey, Jeffrey W.; Selvaratnam, Shivi; Miltner, Robert J.