The ecological implications of rising stream temperatures are a concern to resource managers throughout the Chesapeake Bay watershed. This dataset provides analysis results for the recent status and trends of water temperature for select streams within the Chesapeake Bay watershed. An existing data compilation effort (https://doi.org/10.5066/P92SHG66) was used to gather continuous and discrete temperature data for the status and trend analysis. The status of stream temperature was computed as the change in 2022 in degree Celsius above or below the mean temperature for the reference period (trend interval). Site level trends were developed using generalized additive modeling (GAMs) in the R package “mgcv” for 31 sites with an average of 346 daily value stream temperature measurements per site collected from contemporary periods (2013-2022, 2014-2022, 2013-2021, 2013-2020). Discrete data were evaluated with linear mixed-models (LMMs) to produce a population-level trend for stream temperature. Detailed data preparation information, analytical methods and results are presented and discussed in the associated Scientific Investigative Report (https://doi.org/10.3133/sir20255072).

The hydrologic regime of rivers and streams is a major determinant of habitat quality for fish and aquatic invertebrates. Long-term streamflow data were compiled and multidecadal streamflow trends and ecological flow (EFlow) statistics were calculated in support of the United States Geological Survey (USGS) Chesapeake Bay Science Initiative toward understanding fish habitat and health in the Chesapeake Bay Watershed (CBWS). A dataset comprising all streamgages (n = 409) reporting daily means of streamflow within the CBWS and remaining active as of September 30, 2018 (the end of Water Year [WY] 2018), independent of streamgage installation date, was retrieved from the USGS National Water Information System (NWIS). This dataset was then subset to include only those streamgages with a contiguous timeseries of streamflow data from a start date no earlier than April 1, 1939 (Climate Year [CY] 1940) and no later than October 1, 1999 (WY 2000). The R packages “EGRET” and "Eflowstats" were utilized together to determine streamflow trends and EFlow statistics from the subset (n = 243). Trends and EFlows were computed for the ranges 1940-1969 (n = 90), 1970-1999 (n = 167), and 2000-2018 (n = 243). Streamflow trends were computed for eight annual metrics (1-, 7- and 30-day minima [CY] and maxima [WY], mean and median [WYs]). These streamflow trends provide context for the 178 EFlow statistics (WY) which have been designated to characterize the magnitude, frequency, and duration of extreme high and low flows, the timing of seasonal flows, and the consistency of the historic regime. Files herein include the following Child Items: (1) a table summarizing streamflow trends for three time periods at a minimum of 90 and maximum of 243 streamgages and 500 time-series plots graphically representing those trends; (2) a table summarizing EFlow statistics and the change between each statistic for three time periods at a minimum of 90 and maximum of 243 streamgages; and (3) a GIS shapefile of the original 409 USGS streamgage locations, complete with NWIS attributes, active within the CBWS through September 30, 2018.

The hydrologic regime of rivers and streams is a major determinant of habitat quality for fish and aquatic invertebrates. Long-term streamflow data were compiled and multidecadal streamflow trends and ecological flow (EFlow) statistics were calculated in support of the United States Geological Survey (USGS) Chesapeake Bay Science Initiative toward understanding fish habitat and health in the Chesapeake Bay Watershed (CBWS). A dataset comprising all streamgages (n = 409) reporting daily means of streamflow within the CBWS and remaining active as of September 30, 2018 (the end of Water Year [WY] 2018), independent of streamgage installation date, was retrieved from the USGS National Water Information System (NWIS). This dataset was then subset to include only those streamgages with a contiguous timeseries of streamflow data from a start date no earlier than April 1, 1939 (Climate Year [CY] 1940) and no later than October 1, 1999 (WY 2000). The R packages “EGRET” and "Eflowstats" were utilized together to determine streamflow trends and EFlow statistics from the subset (n = 243). Trends and EFlows were computed for the ranges 1940-1969 (n = 90), 1970-1999 (n = 167), and 2000-2018 (n = 243). Streamflow trends were computed for eight annual metrics (1-, 7- and 30-day minima [CY] and maxima [WY], mean and median [WYs]). These streamflow trends provide context for the 178 EFlow statistics (WY) which have been designated to characterize the magnitude, frequency, and duration of extreme high and low flows, the timing of seasonal flows, and the consistency of the historic regime. Files herein include the following Child Items: (1) a table summarizing streamflow trends for three time periods at a minimum of 90 and maximum of 243 streamgages and 500 time-series plots graphically representing those trends; (2) a table summarizing EFlow statistics and the change between each statistic for three time periods at a minimum of 90 and maximum of 243 streamgages; and (3) a GIS shapefile of the original 409 USGS streamgage locations, complete with NWIS attributes, active within the CBWS through September 30, 2018.

Ecological flow (EFlow) statistics have been designated to characterize the magnitude, frequency, and duration of extreme high- and low-flows, the timing of seasonal flows, and the consistency of the historic regime. This Child Item contains a table of 178 EFlows for the time periods 1940-1969, 1970-1999, and 2000-2018, with absolute and percent change between periods, where applicable. Statistics were computed by Water Year (WY) for all 178 metrics and absolute and percent change were calculated by comparing metrics between combinations of two of the three time periods (1940-1969 and 1970-1999; 1940-1969 and 2000-2018; 1970-1999 and 2000-2018). Streamgages from the original dataset (n = 409) were excluded from one or more time periods of analysis because of extensive data gaps that would yield incomplete EFlows; therefore, stations were indexed into the earliest possible time period relative to their installation date (for example, a streamgage with an operating start year of 1958 would be included in the analysis for the time periods 1970-1999 and 2000-2018), which resulted in different sample sizes for each period: 1940-1969 (n = 90), 1970-1999 (n = 167), and 2000-2018 (n = 243). Similarly, multiple stations were wholly excluded because of frequent discontinuities in the daily mean streamflow through all three time periods. Finally, a streamgage must have fallen within at least two time periods to have a change value. As such, not all stations are represented in the change analysis (change between 1940-1969 and 1970-1999 [n = 90]; change between 1940-1969 and 2000-2018 [n = 90]; change between 1970-1999 and 2000-2018 [n = 167]).

Ecological flow (EFlow) statistics have been designated to characterize the magnitude, frequency, and duration of extreme high- and low-flows, the timing of seasonal flows, and the consistency of the historic regime. This Child Item contains a table of 178 EFlows for the time periods 1940-1969, 1970-1999, and 2000-2018, with absolute and percent change between periods, where applicable. Statistics were computed by Water Year (WY) for all 178 metrics and absolute and percent change were calculated by comparing metrics between combinations of two of the three time periods (1940-1969 and 1970-1999; 1940-1969 and 2000-2018; 1970-1999 and 2000-2018). Streamgages from the original dataset (n = 409) were excluded from one or more time periods of analysis because of extensive data gaps that would yield incomplete EFlows; therefore, stations were indexed into the earliest possible time period relative to their installation date (for example, a streamgage with an operating start year of 1958 would be included in the analysis for the time periods 1970-1999 and 2000-2018), which resulted in different sample sizes for each period: 1940-1969 (n = 90), 1970-1999 (n = 167), and 2000-2018 (n = 243). Similarly, multiple stations were wholly excluded because of frequent discontinuities in the daily mean streamflow through all three time periods. Finally, a streamgage must have fallen within at least two time periods to have a change value. As such, not all stations are represented in the change analysis (change between 1940-1969 and 1970-1999 [n = 90]; change between 1940-1969 and 2000-2018 [n = 90]; change between 1970-1999 and 2000-2018 [n = 167]).

This dataset provides analysis results for status values representing the period of 2015 through 2017 for six indicators of river and stream condition in the Chesapeake Bay watershed. Status (condition at a point in time) was calculated yearly for metrics of the following indicators: stream nutrients and suspended sediment, salinity, temperature, hydromorphology, streamflow and biological assemblages. These yearly status values were then averaged to create mean status values for each indicator and metric. The mean status values were then used to score indicator sites as high quality, low quality, or intermediate quality. Additionally, the relationship between mean status values and three land use/land cover types (developed, agriculture and urban) were analyzed via simple linear regression. Detailed data preparation information, analytical methods and results are presented and discussed in the associated Scientific Investigative Report (https://doi.org/10.3133/sir20255072).

Input data on watershed drainage area characteristics and stream reach geomorphometry for statistical modeling of floodplains, streambanks, and streambeds in the Chesapeake Bay and Delaware River watersheds of the U.S. Mid-Atlantic. Characteristics include selected upstream accumulated attributes (with divergence routing) describing geology, topography, soils, hydrology, and land use for each NHDPlusV2 stream reach from Wieczorek et al. (2018), and the geomorphometry of the local stream reach summarized from Hopkins et al. (2020). These potential predictors were tested for incorporation into Random Forest statistical models to explain and predict spatial variation in floodplain and streambank flux of sediment, fine sediment, sediment-C, sediment-N, and sediment-P and rates of geomorphic change, and streambed sediment characteristics (d50, cover by fine sediment, cover by fine and sand sediment).

Input data on watershed drainage area characteristics and stream reach geomorphometry for statistical modeling of floodplains, streambanks, and streambeds in the Chesapeake Bay and Delaware River watersheds of the U.S. Mid-Atlantic. Characteristics include selected upstream accumulated attributes (with divergence routing) describing geology, topography, soils, hydrology, and land use for each NHDPlusV2 stream reach from Wieczorek et al. (2018), and the geomorphometry of the local stream reach summarized from Hopkins et al. (2020). These potential predictors were tested for incorporation into Random Forest statistical models to explain and predict spatial variation in floodplain and streambank flux of sediment, fine sediment, sediment-C, sediment-N, and sediment-P and rates of geomorphic change, and streambed sediment characteristics (d50, cover by fine sediment, cover by fine and sand sediment).

The assessment of different aspects of hydromorphic conditions through time and space may assist in explaining the various stressors contributing to stream condition such as habitat alteration. This dataset provides results for status and trends of hydromorphology (the interplay of geomorphology, hydraulics, and physical habitat) of streams and rivers in the Chesapeake Bay watershed. These two separate analyses for status and trends in hydromorphology are derived from: analysis of field-based rapid habitat metrics collected by multiple jurisdictions during habitat surveys; and specific gage analyses using data collected during routine streamflow measurements at USGS streamgages. Results from the rapid habitat and stream gage status and trend analyses are provided below in the two respective Child Items. Detailed data preparation information, analytical methods and results are presented and discussed in the associated Scientific Investigative Report (https://doi.org/10.3133/sir20255072).

This data set contains U.S. Geological Survey (USGS) streamgage identification numbers, begin and end years of the periods of streamflow record tested, Sen slope trends in the annual minimum 7-day streamflow for the period of record tested, the p-values (significance) of the trends, and the trend Sen slopes standardized by the standard deviations of the residual errors defined as the difference between observations and the Sen slope lines, for 174 USGS streamgages with 56 to 75 years of record in the Chesapeake Bay watershed, Mid-Atlantic U.S.