Grandkids here for a couple weeks this summer... pool and splash ideas?

My son is dropping the grandkids with me for two weeks in July and I am already trying to plan ahead so I don't lose my mind lol. I've got a little one who's 4 and two older ones around 8 and 10, so I need a mix of things. Is the pool at Buhl Park open yet for the season? And does anybody know of a good splash pad or anywhere with water to cool off when it gets hot? Honestly I'll take anything that gets them outside and tires them out 😅 Thank you in advance!