The U.S. Geological Survey (USGS) developed and calibrated a Water Quality Analysis Simulation Program (WASP) model (version 8.4) for the Barnegat Bay-Little Egg Harbor Estuary (hereafter referred to as 'the Estuary'), New Jersey. This model was externally coupled with a previously developed hydrodynamic model (Defne and Ganju, 2015 and 2018) to simulate dissolved oxygen, nutrient cycling, and phytoplankton dynamics. Boundaries and loads developed for the model were based on hydrologic and water-quality data collected by the New Jersey Department of Environmental Protection (NJDEP) and the USGS. The model was simulated and calibrated using data collected from March 7 through September 30, 2012. The calibrated model was used to evaluate three compliance scenarios to quantify the magnitude of watershed nitrogen reductions required to achieve measurable improvements in water quality. This modeling study was part of a larger, multiyear effort by the NJDEP to assess the ecological health of the Estuary. This USGS data release contains all input and output files for the simulations described in the associated journal article (https://doi.org/10.1016/j.marpolbul.2025.117748). References: - Defne, Z., and Ganju, N.K., 2015, Quantifying the residence time and flushing characteristics of a shallow, back-barrier estuary—Application of hydrodynamic and particle tracking models: Estuaries and Coasts, v. 38, no. 5, p. 1719-1734, accessed June 13, 2024, at https://doi.org/10.1007/s12237-014-9885-3. - Defne, Z., and Ganju, N.K., 2018, USGS Barnegat Bay hydrodynamic model for March to September 2012: U.S. Geological Survey data release, accessed June 13, 2024, at https://doi.org/10.5066/F7SB44QS.