Lori Sprague is currently the coordinator of the Surface-Water Status and Trends team in the USGS National Water-Quality Assessment Project. The goals of the team are to (1) determine current conditions and long term trends in water chemistry and aquatic ecology in the Nation’s streams and rivers, (2) evaluate the geographic distribution of improving and deteriorating water-quality conditions Nationwide, (3) determine the potential impact of these conditions on the health of humans and aquatic life, and (4) identify the major causes of long term trends in water quality. See https://water.usgs.gov/nawqa/swtrends/ and https://nawqatrends.wim.usgs.gov/swtrends/ for more information. Lori is also the USGS representative on the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force coordinating committee. The Task Force works to understand the causes and effects of eutrophication in the Gulf of Mexico; coordinate activities to reduce the size, severity, and duration of the seasonal hypoxic zone in the Gulf of Mexico; and ameliorate the effects of hypoxia. See https://www.epa.gov/ms-htf/ for more information.
Science and Products
Modeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change
Causal attribution of changes in water quality often consists of correlation, qualitative reasoning, listing references to the work of others, or speculation. To better support statements of attribution for water-quality trends, structural equation modeling was used to model the causal factors of total phosphorus loads in the Chesapeake Bay...Ryberg, Karen R.; Blomquist, Joel; Sprague, Lori A.; Sekellick, Andrew J.; Keisman, Jennifer
Water-quality and streamflow datasets used in Seasonal Kendall trend tests for the Nation’s rivers and streams, 1972-2012
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-...Mills, Taylor J.; Sprague, Lori A.; Murphy, Jennifer C.; Riskin, Melissa L.; Falcone, James A.; Stets, Edward G.; Oelsner, Gretchen P.; Johnson, Henry M.
Water-quality trends in the nation’s rivers and streams, 1972–2012—Data preparation, statistical methods, and trend results
Since passage of the Clean Water Act in 1972, Federal, State, and local governments have invested billions of dollars to reduce pollution entering rivers and streams. To understand the return on these investments and to effectively manage and protect the Nation’s water resources in the future, we need to know how and why water quality has been...Oelsner, Gretchen P.; Sprague, Lori A.; Murphy, Jennifer C.; Zuellig, Robert E.; Johnson, Henry M.; Ryberg, Karen R.; Falcone, James A.; Stets, Edward G.; Vecchia, Aldo V.; Riskin, Melissa L.; De Cicco, Laura A.; Mills, Taylor J.; Farmer, William H.
Challenges with secondary use of multi-source water-quality data in the United States
Combining water-quality data from multiple sources can help counterbalance diminishing resources for stream monitoring in the United States and lead to important regional and national insights that would not otherwise be possible. Individual monitoring organizations understand their own data very well, but issues can arise when their data are...Sprague, Lori A.; Oelsner, Gretchen P.; Argue, Denise M.
Antecedent flow conditions and nitrate concentrations in the Mississippi River basin
The relationship between antecedent flow conditions and nitrate concentrations was explored at eight sites in the 2.9 million square kilometers (km2) Mississippi River basin, USA. Antecedent flow conditions were quantified as the ratio between the mean daily flow of the previous year and the mean daily flow from the period of record (Qratio), and...Murphy, Jennifer C.; Hirsch, Robert M.; Sprague, Lori A.
Nitrate in the Mississippi River and its tributaries, 1980-2010: an update
Nitrate concentration and flux were estimated from 1980 through 2010 at eight sites in the Mississippi River Basin as part of the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS). These estimates extend the results from a previous investigation that provided nitrate estimates from 1980 through 2008 at the same...Murphy, Jennifer C.; Hirsch, Robert M.; Sprague, Lori A.
Estimated anthropogenic nitrogen and phosphorus inputs to the land surface of the conterminous United States--1992, 1997, and 2002
Anthropogenic inputs of nitrogen and phosphorus to each county in the conterminous United States and to the watersheds of 495 surface-water sites studied as part of the U.S. Geological Survey National Water-Quality Assessment Program were quantified for the years 1992, 1997, and 2002. Estimates of inputs of nitrogen and phosphorus from biological...Sprague, Lori A.; Gronberg, Jo Ann M.
Relating management practices and nutrient export in agricultural watersheds of the United States
Relations between riverine export (load) of total nitrogen (N) and total phosphorus (P) from 133 large agricultural watersheds in the United States and factors affecting nutrient transport were evaluated using empirical regression models. After controlling for anthropogenic inputs and other landscape factors affecting nutrient transport-such as...Sprague, Lori A.; Gronberg, Jo Ann M.
Nitrate in the Mississippi River and its tributaries, 1980 to 2008: Are we making progress?
Changes in nitrate concentration and flux between 1980 and 2008 at eight sites in the Mississippi River basin were determined using a new statistical method that accommodates evolving nitrate behavior over time and produces flow-normalized estimates of nitrate concentration and flux that are independent of random variations in streamflow. The...Sprague, Lori A.; Hirsch, Robert M.; Aulenbach, Brent T.
Trends in suspended-sediment loads and concentrations in the Mississippi River Basin, 1950–2009
Trends in loads and concentrations of suspended sediment and suspended sand generally were downward for stations within the Mississippi River Basin during the 60-, 34-, and 12-year periods analyzed. Sediment transport in the lower Mississippi River has historically been, and continues to be, most closely correlative to sediment contributions from...Heimann, David C.; Sprague, Lori A.; Blevins, Dale W.
A Web-Based Decision Support System for Assessing Regional Water-Quality Conditions and Management Actions
The U.S. Geological Survey National Water Quality Assessment Program has completed a number of water-quality prediction models for nitrogen and phosphorus for the conterminous United States as well as for regional areas of the nation. In addition to estimating water-quality conditions at unmonitored streams, the calibrated SPAtially Referenced...Booth, N.L.; Everman, E.J.; Kuo, I.-L.; Sprague, L.; Murphy, L.
Nutrient sources and transport in the Missouri River Basin, with emphasis on the effects of irrigation and reservoirs
SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were used to relate instream nutrient loads to sources and factors influencing the transport of nutrients in the Missouri River Basin. Agricultural inputs from fertilizer and manure were the largest nutrient sources throughout a large part of the basin, although atmospheric...Brown, J.B.; Sprague, L.A.; Dupree, J.A.