It is unlawful for any person, firm, corporation or association having the control, ownership or management of any canal within the city to permit the same, when water is not flowing therein, to be or remain in an unsanitary condition; and it is made the duty of any such person, firm, corporation or association, having the control, ownership or management of any such canal, immediately upon turning the water out of such canal, to remove from the bed thereof any and all rubbish, trash, junk, rejected or waste vegetable or animal matter, filth or garbage of any kind whatsoever, and so to turn the waters out of such canal that there shall not remain in the bed thereof any pools of such waters. (Prior code § 8.52.010)