汚す
よごす · yogosu · JLPT N3 · verb-godan
to make dirty
🏭 Yo, go sue the factory that dirties the river: yogosu = to pollute
汚 carries the water radical 氵, because the first thing people polluted was water. Same kanji in 汚い (kitanai, dirty). Pair: 汚す yogosu = you make it dirty; 汚れる yogoreru = it gets dirty.