Since 2016, IPE has been collecting water quality data released by governments across China, organizing and classifying them, and displaying them on the Blue Map website and app. IPE developed the City Water Environment Index (CWEI) in 2019, which compares surface water conditions in different cities across China. Starting from this issue, IPE will publish quarterly reports on the CWEI on a regular basis. The first report will be for the third quarter of 2021.