Regression diagnostics (including number of observations, residual variance, R squared, bias percentage, Akaike's information criterion (AIC), Nash-Sutcliffe efficiency) and coefficients (variable, estimate, standard error, Z score, p-value) for the tributary nutrient and sediment monitoring program on the Great Lakes, 2011-2013

Yearly estimated loads by site (Great Lakes tributary) and constituent.

Yearly estimated loads by site (Great Lakes tributary) and constituent.

Daily estimated loads by site (Great Lakes tributary) and constituent.

Monthly average estimated loads by site (Great Lakes tributary) and constituent.

Monthly average estimated loads by site (Great Lakes tributary) and constituent.

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-term consistent and comparable monitoring has been conducted on streams and rivers throughout the Nation. Outside of the NAWQA project, the USGS and other Federal, State, and local agencies also have collected long-term water-quality data to support their own assessments of changing water-quality conditions. Data from these multiple sources have been combined to support one of the most comprehensive assessment conducted to date of water-quality trends in the United States. Ultimately, these data will provide insight into how natural features and human activities have contributed to water-quality changes over time in Nation’s streams and rivers. This USGS data release contains all of the input and output files necessary to reproduce the results from the Weighted Regressions on Time, Discharge, and Season (WRTDS) models described in the associated U.S. Geological Survey Scientific Investigations Report. Data preparation for input to the models is also fully described in the above-mentioned report.

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-term consistent and comparable monitoring has been conducted on streams and rivers throughout the Nation. Outside of the NAWQA project, the USGS and other Federal, State, and local agencies also have collected long-term water-quality data to support their own assessments of changing water-quality conditions. Data from these multiple sources have been combined to support one of the most comprehensive assessment conducted to date of water-quality trends in the United States. Ultimately, these data will provide insight into how natural features and human activities have contributed to water-quality changes over time in Nation’s streams and rivers. This USGS data release contains all of the input and output files necessary to reproduce the results from the Weighted Regressions on Time, Discharge, and Season (WRTDS) models described in the associated U.S. Geological Survey Scientific Investigations Report. Data preparation for input to the models is also fully described in the above-mentioned report.

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-term consistent and comparable monitoring has been conducted on streams and rivers throughout the Nation. Outside of the NAWQA project, the USGS and other Federal, State, and local agencies also have collected long-term water-quality data to support their own assessments of changing water-quality conditions. Data from these multiple sources have been combined to support one of the most comprehensive assessment conducted to date of water-quality trends in the United States. Ultimately, these data will provide insight into how natural features and human activities have contributed to water-quality changes over time in Nation’s streams and rivers. This USGS data release contains all of the input and output files necessary to reproduce the results from the Weighted Regressions on Time, Discharge, and Season (WRTDS) models described in the associated U.S. Geological Survey Scientific Investigations Report. Data preparation for input to the models is also fully described in the above-mentioned report.

This data release provides computed rainfall (rain total, duration, intensity, erosivity and antecedent rainfall) and flow (flow volume, flow-weighted mean concentrations, total loads, and total yields) metrics from monitored precipitation, discharge, and water quality (nutrients and sediment concentrations) data collected at U.S. Geological Survey edge-of-field (EOF) monitoring sites located in five Great Lakes States (Wisconsin, Michigan, Ohio, Indiana, and New York). EOF monitoring sites are installed at the edge of agricultural fields, either on the field surface or using subsurface tiles, where runoff can be intercepted and channeled through monitoring equipment before it enters the natural stream system. The methods used to collect this data followed USGS EOF monitoring methods (https://pubs.usgs.gov/of/20081015/). These EOF monitoring sites are located at private farms under a variety of farming systems, landscape settings, drainage areas, soil types, and climates. Site information is provided in the ‘EOF_Site_Table.csv’ data table. Rainfall metrics were computed for EOF site locations and are provided in the ‘All_EOF_RainEvents.csv’ data table. Rainfall was directly monitored at many, but not every EOF monitoring site. EOF monitoring sites without on-site rainfall data were associated to rainfall data measured at a nearby EOF monitoring site or meteorological site. Rainfall was combined into a single event if it occurred within 2 hours of the previous rainfall. Flow data were computed for each flow event at each EOF monitoring site and are available in the ‘All_EOF_StormEventLoadsFormatted.csv’ data table. A flow event was defined as any period of flow at a site that was classified as a storm and represents flow that was related to rainfall or snowmelt. There were occurrences of continuous flow between rain events, which were not associated with a period of rainfall or snowmelt, likely due to excessive soil saturation or shallow groundwater discharge. These periods of intermittent tile discharge were not classified as a storm. Multiple precipitation and flow events were combined if they occurred within two hours of each other to account for similar rainfall/runoff characteristics. Rainfall metrics and flow data were then calculated for these combined events at each EOF monitoring site and available in the ‘All_EOF_StormEventLoadsRainCalculated.csv’ data table.