Kalamalka Lake Provincial Park features an off-leash dog beach located approximately a kilometer down the Crest Trail. This trail has some elevation to it so be prepared for a 15-20 minute moderate walk. Once you reach the beach there is a fairly large area where your dog can have a swim (and you can too!)
There is free parking at the trailhead in 2 lots, but these do fill up quickly on summer days. There are bathrooms at the beginning of the trail, next to the parking area.