Data Repository for StreamCatNNI and LakeCatNNI: Watershed and Local Catchment Nitrogen and Phosphorus Budgets for U.S. Streams and Lakes

Spatially explicit nutrient budgets are critical for managing nutrients and improving water quality. Yet, these budgets are resource-intensive to develop at the scales and extents needed for achieving management goals. In this paper we introduce StreamCatNNI and LakeCatNNI, an integration of the United States Environmental Protection Agency's (USEPA) Next Generation National Nutrient Inventory (NNI) with the StreamCat database. The NNI provides 30-year annual time-series (1987-2017) of nitrogen (N) and phosphorus (P) budgets for US counties. The NNI¿s integration with StreamCat yields watershed and local catchment N and P budgets for ~2.64 million stream segments and 378,088 lakes. These budgets contain major anthropogenic and natural inputs, outputs, agricultural surplus, and legacy agricultural surplus for N and P. StreamCatNNI and LakeCatNNI data were calculated using 1) a tabular dasymetric apportionment process to downscale NNI nutrient data to local drainages, then 2) the StreamCat accumulation framework to derive watershed nutrient budgets. StreamCatNNI and LakeCatNNI data underwent a variety of spatial quality assurance evaluations, and workflow components are publicly available for replication.