This data release contains seasonal application estimates of nitrogen and phosphorus to cropland for watersheds draining to the Puget Sound and the Strait of Juan de Fuca, Washington. The data, which cover the years 2005 through 2020, were used as input to seasonal Spatially Referenced Regression On Watershed attributes (SPARROW) total nitrogen and total phosphorus models that were used to assess nutrient loadings to Puget Sound. The values constitute the seasonal nitrogen and phosphorus application for each incremental catchment represented in the SPARROW models.

This data release contains estimated seasonal total nitrogen (TN) and total phosphorus (TP) loads during 2005 through 2020 in selected streams of the watersheds draining to Washington waters of the Salish Sea (Puget Sound region). Two load estimation methods were used: Fluxmaster (Schwarz and others, 2006, https://doi.org/10.3133/tm6B3) and Weighted Regression on Time, Discharge, and Season (WRTDS) with Kalman filtering (Hirsch and De Cicco, 2015, https://doi.org/10.1016/j.envsoft.2015.07.017). Together with the water-quality data, streamflow data, and estimated nitrogen and phosphorus loads, this release also provides copies of computer programming script that can be used to recreate the load estimates or modified for similar applications (see Process Steps). Seasonal TN and TP loads paired with streamflow were estimated at 50 locations. For convenience, seasonal summaries are also provided of observed streamflow at 128 locations and of observed water temperature at 29 locations.

This data release contains estimated seasonal total nitrogen (TN) and total phosphorus (TP) loads during 2005 through 2020 in selected streams of the watersheds draining to Washington waters of the Salish Sea (Puget Sound region). Two load estimation methods were used: Fluxmaster (Schwarz and others, 2006, https://doi.org/10.3133/tm6B3) and Weighted Regression on Time, Discharge, and Season (WRTDS) with Kalman filtering (Hirsch and De Cicco, 2015, https://doi.org/10.1016/j.envsoft.2015.07.017). Together with the water-quality data, streamflow data, and estimated nitrogen and phosphorus loads, this release also provides copies of computer programming script that can be used to recreate the load estimates or modified for similar applications (see Process Steps). Seasonal TN and TP loads paired with streamflow were estimated at 50 locations. For convenience, seasonal summaries are also provided of observed streamflow at 128 locations and of observed water temperature at 29 locations.

This data release contains the watershed ancillary data that were used as input for a set of dynamic Spatially Referenced Regression On Watershed attributes (SPARROW) models for watersheds draining to Puget Sound and the Strait of Juan de Fuca, Washington for the years 2005 - 2020. The SPARROW models were used to estimate mean seasonal total nitrogen and total phosphorous conditions and the delivery of those nutrients to Puget Sound and the Strait of Juan de Fuca. The data sets in each child item, which consists of a collection of CSV files, represents landscape conditions in the incremental catchments that made up the hydrologic network used in the SPARROW modeling. The conditions for catchments that were partially or fully outside the domain of the original landscape data were estimated by extrapolating the conditions from nearby catchments.

This data release contains the watershed ancillary data that were used as input for a set of dynamic Spatially Referenced Regression On Watershed attributes (SPARROW) models for watersheds draining to Puget Sound and the Strait of Juan de Fuca, Washington for the years 2005 - 2020. The SPARROW models were used to estimate mean seasonal total nitrogen and total phosphorous conditions and the delivery of those nutrients to Puget Sound and the Strait of Juan de Fuca. The data sets in each child item, which consists of a collection of CSV files, represents landscape conditions in the incremental catchments that made up the hydrologic network used in the SPARROW modeling. The conditions for catchments that were partially or fully outside the domain of the original landscape data were estimated by extrapolating the conditions from nearby catchments.

This data release contains monthly deposition estimates of wet and total inorganic nitrogen (reduced and oxidized) for watersheds draining to the Puget Sound and the Strait of Juan de Fuca, Washington. The data, which cover the years 2005 through 2020, were used as input to a seasonal Spatially Referenced Regression On Watershed attributes (SPARROW) total nitrogen model that was used to assess nutrient loadings to Puget Sound and the Strait of Juan de Fuca. The values constitute the monthly nitrogen deposition for each incremental catchment represented in the SPARROW models.

This data release contains seasonal source-specific estimates of total nitrogen (TN) and total phosphorus (TP) loads from watersheds draining to Washing water of the Salish Sea (Puget Sound region,12,314 e2NHDPlusV2 reaches plus 2 added transfer reaches) using a dynamic SPARROW (Spatially Referenced Regressions on Watershed attributes) model. Input data, output predictions, model control files, and model source code are provided to fully reproduce results. The modeled period was from January 2005 through December 2020 in seasonal time steps, or 64 periods, and the following seasonal definitions were applied: winter includes January, February, and March; spring includes April, May, and June; summer includes July, August, and September; and fall includes October, November, and December.

This data release contains estimated monthly point-source nutrient loads for 97 municipal wastewater treatment plants, 20 industrial facilities, and 46 fish hatcheries and other aquaculture facilities that discharge within the watersheds draining to Puget Sound and the Strait of Juan de Fuca in Washington, or discharge directly to those water bodies. The data, which cover the years 2005 through 2020, were used as input to a set of seasonal SPARROW total nitrogen and total phosphorus SPARROW models that were used to assess nutrient loadings to Puget Sound.

This data release contains estimated monthly point-source nutrient loads for 97 municipal wastewater treatment plants, 20 industrial facilities, and 46 fish hatcheries and other aquaculture facilities that discharge within the watersheds draining to Puget Sound and the Strait of Juan de Fuca in Washington, or discharge directly to those water bodies. The data, which cover the years 2005 through 2020, were used as input to a set of seasonal SPARROW total nitrogen and total phosphorus SPARROW models that were used to assess nutrient loadings to Puget Sound.

The existing long-term Total Nitrogen (TN) and Total Phosphorus (TP) steady-state models, originally developed on a regional scale for the Pacific Region of the United States (Wise, 2019), were utilized to estimate TN and TP loads for the Clear Lake watershed. To support this analysis, input data for the Pacific Region model were updated to reflect climate, land use, and agricultural activities for the 2016-2024 period. Following these updates, the models were run in prediction mode, using model coefficients from the 2012 Pacific Region TN and TP SPARROW models. Model data set updates included incorporating the 2019 National Land Cover Data (NLCD), 2017 county-level applied agricultural fertilizer and manure data, updated streamflow data representing 2016-2024 conditions, and adjustments for areas affected by the 2017 and 2018 wildfires in the Clear Lake watershed. The revised Pacific Region SPARROW models were then run in prediction mode, and the resulting TN and TP load estimates were compared to those from the 2012 Pacific Region model to assess changes in TN and TP loads relative to historical conditions. Initially developed in the Statistical Analysis System (SAS), the Pacific Region SPARROW models were converted to R (RSPARROW) for this analysis. RSPARROW is available at https://doi.org/10.5066/P9G64CAN.