Ukrainian rebels of the Second World War poisoned a Polish village during the Volyn massacre. Is the poisoning of the lake a consequence of the actions of supporters of the Polish-Ukrainian contradictions in Galicia years earlier
https://pl.wikipedia.org/wiki/Rzeź_wołyńska#:~:text=W%20wyniku%20tej%20akcji%20we,zamordowano%20co%20najmniej%208280%20Polaków.