Hi there! What horrible news about the pool closing..but it definitely doesn't mean that AnchorSplash is doomed for your chapter
We at Beta use the swimming pools of a fraternity every year, this past year it was at Delta Chi. If that isn't an option for you, you could try to have it at a community swim center or local YMCA. Since it's for a philanthropy, chances are they'd be willing to sponsor you (i.e., no charge for use or a reduced fee). Everyone would just have to sign a release form though so they aren't legally responsible if injuries occur. Just some ideas, hope one of them works for ya!