River Watch: Spotting City and Farm Pollution

A new system has been set up to tell the difference between pollution that comes from a city and pollution that comes from farms or factories. The idea is to help people fix the river faster by knowing exactly where bad water is coming from. The project was tested on the Sile River in Treviso, Italy, between 2021 and 2023. Six fixed stations were built along the river. Three of them have fancy sensors that can read many water qualities at once and keep samples cold for later lab work. The other three only measure how fast the water flows and how deep it is, using radar. Two portable samplers were added so that researchers can collect water from spots that the fixed stations miss. Data is taken both all the time and once a day.The system records how water behaves when it rains and when it is dry, giving a clear picture of the river’s health. Scientists then use math tools like correlation and principal component analysis to find patterns in the data. The results show that bacteria called Escherichia coli and a total phosphorus measure are mainly linked to the city’s sewage system. In contrast, nitrate levels point to farming activities nearby. With this knowledge, city planners can target the right places for cleanup and farmers can adjust their practices. After two years, the system proved useful for telling city pollution from farm pollution and can be used in other rivers that face similar problems.