Chesapeake Bay has a long history of nutrient pollution resulting in degraded water quality. However, we report improvements in chlorophyll a in surface waters and dissolved oxygen in bottom waters at one of three estuarine stations in the Choptank tributary of Chesapeake Bay. We updated a previous nutrient budget for the estuary constructed for reference year 1998 using rates of atmospheric deposition, inputs of watershed diffuse sources (primarily agriculture), and discharges of point sources (primarily human waste) for reference year 2017. Parallel trends suggest that improvements in water quality at the one station were likely due to 20% reductions in direct atmospheric deposition on the estuary’s surface and 78–95% reductions in wastewater N and P due to installation of tertiary treatment. The agricultural sector, the dominant source of N and P, appeared to provide little contribution to improved water quality during this period. Although efforts to reduce nutrient losses from agriculture are common throughout the Choptank basin, widespread reductions from agricultural diffuse sources could make large contributions to improved water quality at all stations in the estuary. The response in the Choptank is similar to those observed elsewhere in the USA, Europe, Australia, and New Zealand due to improved wastewater treatment. Similar to our findings, the upper Potomac River of Chesapeake Bay saw improvements driven by reductions in atmospheric deposition. Unfortunately, few studies elsewhere have shown improvements in water quality due to agricultural management. The data presented here indicate that public and industrial investments in reductions of atmospheric emissions and upgrades to wastewater treatment plants have improved estuarine water quality in the Choptank.

切萨皮克湾（Chesapeake Bay）的养分污染历史悠久，导致水质下降。但是，我们报告了叶绿素a的改善切萨皮克湾Choptank支流的三个河口站之一的地表水和底水中的溶解氧。我们使用1998年参考年的大气沉积率，集水区扩散源（主要是农业）和点源（主要是人类废物）的排放量，更新了1998年参考年份河口的先前养分预算。平行趋势表明，改善的趋势一站的水质下降可能是由于河口表面直接大气沉积物减少了20％，以及由于安装了第三级处理而使废水中的氮和磷减少了78-95％。在此期间，作为氮和磷的主要来源的农业部门似乎对改善水质几乎没有贡献。尽管在整个Choptank盆地中，为减少农业养分流失所做的努力是普遍的，但从农业广泛扩散源中大量减少养分，可以为改善河口所有水位做出巨大贡献。由于改善了废水处理，Choptank中的响应类似于在美国，欧洲，澳大利亚和新西兰的其他地区。与我们的发现相似，切萨皮克湾的波托马克河上游的大气层沉积减少也带来了改善。不幸的是，其他地方很少有研究表明由于农业管理而改善了水质。这里提供的数据表明，为减少大气排放和升级废水处理厂而进行的公共和工业投资已经改善了Choptank的河口水质。