May girls swim in a place where there are male lifeguards?
This is not acceptable. A Rav should be consulted in extenuating circumstances. See Shu"t Divrie Yatziv E"H 45. https://asktherav.com/a-guide-for-a-yiddishe-summer-experience-%d7%a4%d7%a1%d7%a7%d7%99-%d7%93%d7%99%d7%a0%d7%99%d7%9d-%d7%9c%d7%91%d7%a0%d7%95%d7%aa-%d7%97%d7%91%d7%93-%d7%9e%d7%90%d7%aa-%d7%a8%d7%91%d7%a0%d7%99/