If animal control is anything like what we have here, what her dad's doing isn't enough to get him in trouble, unless they're actually out of water when the officer stops. A weekend isn't enough time for it to get that gross and dirty.
I'm glad those dogs have you, goettling. Just be careful about jumping the fence if the one is scared and doesn't know you well.
Sounds to me like your dad sent the e-mail just to get under your skin. Why wouldn't he ask if you could keep them for the weekend or give you a key to the gate otherwise.
Would he consider getting them a kiddie pool if you suggested it or letting them have one if you brought it? That way they'd have plenty of water to drink and cool off in. They don't cost much. I've seen them for $5 or $6.