Water Quality Data of the Chicago, Calumet, and Des Plaines River Systems in the Chicago Metropolitan Region

Compiled water quality data of the Chicago, Calumet, and Des Plaines River Systems from 1975 to 2018. Data were collected as part of the Metropolitan Water Reclamation District's Ambient Water Quality Monitoring program. A study was carried out to evaluate water quality trends from 1975 to 2012 and from 2013 to 2018 in the Chicago, Calumet, and Des Plaines River Systems in Cook County, Illinois, in order to investigate the impact of practices carried out by the Metropolitan Water Reclamation District of Greater Chicago. Data from 41 monitoring locations were compiled and analyzed for 11 water quality parameters. The seasonal Kendall test was performed on each variable at each location to analyze for long-term monotonic trends. Wilcoxon Rank-Sum test was used to test for significant differences in median water quality constituents between time periods to point to practices that changed water quality during the study period. For most sampling locations, long-term trend analyses showed significant downward trends for total organic carbon (TOC), total Kjeldahl nitrogen (TKN), ammonium nitrogen (NH4-N), total suspended solids (TSS), fecal coliform (FC), and sulfate and significant upward trends for dissolved oxygen (DO), chloride, and temperature. Results for total phosphorus were inconsistent across sampling locations. Improvements in TKN, NH4-N, TOC, TSS, FC, and DO concentrations over four decades demonstrated the beneficial outcome from the expansion of secondary treatment systems at water reclamation plants, implementation of the Tunnel and Reservoir Plan System, instream and side-stream elevated pool aeration stations, and effluent disinfection. The study is described in the article entitled "Long-Term Trends in Water Quality Show a Reduction in the Urban Stream Syndrome in the Chicago Metropolitan Region with Investment in Wastewater Infrastructure, Deep Tunnels, and Reservoirs". Supporting Information for this manuscript is attached.

本数据集汇编了1975年至2018年芝加哥河、卡卢梅特河（Calumet River）与德斯普兰斯河（Des Plaines River）水系的水质监测数据。相关数据采集自芝加哥大都会水再生管理局（Metropolitan Water Reclamation District）的环境水质监测项目。为探究大芝加哥地区大都会水再生管理局的治理实践对河流水质的影响，本研究针对伊利诺伊州库克县境内的芝加哥、卡卢梅特及德斯普兰斯河系，分别对1975-2012年与2013-2018年两个时段的水质变化趋势开展评估。本研究共整合了41个监测点位的数据集，针对11项水质参数展开分析。采用季节性Kendall检验（Seasonal Kendall test）对各点位的各项变量开展长期单调趋势分析；采用Wilcoxon秩和检验（Wilcoxon Rank-Sum test）对比不同时段水质组分的中位数差异，以此识别研究期间对水质产生显著影响的治理措施。针对多数监测点位的长期趋势分析结果显示：总有机碳（total organic carbon, TOC）、凯氏总氮（total Kjeldahl nitrogen, TKN）、氨氮（ammonium nitrogen, NH4-N）、总悬浮颗粒物（total suspended solids, TSS）、粪大肠菌群（fecal coliform, FC）以及硫酸盐浓度均呈现显著下降趋势；而溶解氧（dissolved oxygen, DO）、氯化物与水温则呈现显著上升趋势。总磷的分析结果在各监测点位间存在不一致性。四十余年来总凯氏氮、氨氮、总有机碳、总悬浮颗粒物、粪大肠菌群及溶解氧浓度的改善情况，印证了污水处理厂二级处理系统扩容、隧道与水库计划系统（Tunnel and Reservoir Plan System）的实施、河道及支流高位水池曝气站的投用，以及出水消毒工艺落地所带来的积极治理成效。本研究的相关内容已发表于题为《长期水质趋势表明：依托污水处理基础设施、深层隧道与水库建设，芝加哥都会区城市河流综合征有所缓解》的学术论文，其支撑性材料已随本文附呈。