Nitrogen (N) in fertilizer and manure applied to croplands is a prominent cause of nutrient pollution in New York State (NYS)1. Excess N ends up in waterways through runoff and groundwater infiltration, which results in eutrophication of nearby water bodies and fuels the release of nitrous oxide, a greenhouse gas2. Because of these water quality impacts, NYS agencies charged with managing the state’s water bodies have programs designed to help agricultural communities reduce the nutrient concentrations in farmland runoff (e.g., the Department of Agriculture and Market’s Agricultural Non-point Source Abatement and Control Program). Subsurface tile drainage is a prevalent agricultural management practice designed to improve crop yields in areas with high water tables or poorly drained soils3. This technique involves the installation of subsurface pipes (tiles) beneath the crop root zone to facilitate the removal of excess water, which enhances soil aeration and root development. Research surveys conducted by the US. Department of Agriculture (USDA) have shown that many farms in NYS use tile drainage to increase crop yields and improve soils4. However, tile drainage also increases baseflow in watersheds, elevates annual runoff volumes and reduces groundwater travel times4. Given these factors as well as the N-basedfertilizers used by farms, there is a high potential for increased surface water nutrient pollution in watersheds with a high density of tile drainage 5-6. However, no work has established whether such a relationship exists in NYS, and the state’s non-point source pollution programs do not consider tile drainage as a target for remediation. Because tile-drained areas are invariably associated with crop cover, there is limited research that examines the impact of tile drainage on N pollution independently from crop cover7. To address this gap, this study evaluates the associations between tile drainage and surface water N concentrations in NYS by integrating water quality data with a novel spatial dataset of tile drainage and additional land use information. Our objective is to isolate the specific impacts of tile drainage on surface water N concentrations from the more general impacts of agricultural land cover. Ultimately, the goal of this work is to provide decision-relevant information that can help state agencies better tailor agricultural land management policies and programs to efficiently and effectively improve water quality across NYS rivers and streams.