Publication of EPA’s Nutrient Inventory is a critical step towards thorough mapping and accounting of sources of N and P to US landscapes. However, summaries of nutrients within accumulative watersheds are needed to develop accurate watershed-level nutrient budgets and relate landscape inputs to instream nutrient concentrations. This subproduct will accumulate the Nutrient Inventory across available years for all streams and lakes within the medium resolution National Hydrography Dataset Plus version 2 (NHDPlus), i.e., 2.6 million stream segments and nearly 400,000 lakes across the conterminous US. These data will allow OW to easily and rapidly identify the dominant sources of N or P for any stream segment or lake in the US. Further, these data will be made accessible through the EPA’s StreamCat and LakeCat datasets and a soon-to-be released online database and an application programming interface (API). This database and API will make nutrient watershed accumulations readily accessible and easily integrated by a variety of OW programs and tools. Finally, the accumulated nutrient data will serve as the basis for a multiple proposed StRAP subproducts and models in SSWR.401, SSWR.404, and SSWR.405. These data will contribute directly to OW, region, and state efforts to identify and reduce non-point nutrient sources. Having spatially explicit data about nutrient sources and loads can help target and inform restoration and conservation efforts, as well as more formal TMDLs, nutrient reduction plans, and groundwater management approaches. This subproduct will produce a database of accumulated nutrient values for at least 2.6 million stream segments and 400,000 lakes of the medium resolution National Hydrography Dataset Plus version 2 (NHDPlus). These data will be made accessible through the StreamCat and LakeCat datasets. They will also be made available as an online database with application programming interface (API) that will facilitate data acquisition and use by OW and state partners. This database will provide a state-of-the science accounting of nutrient sources that drain to all streams and lakes in the conterminous US. It will allow EPA and state partners to identify dominant sources of N and P to individual waterbodies and will greatly facilitate nutrient reduction strategies and planning.