There are two reasons. First, there is saline-alkali land near here, and there seems to be a sulfuric acid field next to it. Things are not easy. Second, the vendors around here always throw rubbish into it. Over time, that's it. There is a reason why schools only collect garbage once a year, but don't bury it. Guyun University is in the suburbs. The place where the ancient emperors went to school was called Biyong, surrounded by water. This gutter and the two lakes in the school just happened to be lucky. . .