Dog Pond - Place a plastic kiddie pool in the ground. It'd be easy to clean and looks nicer than having it above ground. Big dogs can't chew it up or drag it around. Then in winter months turn it in to a fire pit!
Incredible Ideas for Making Your Home a Pet Heaven
The unique design of the Orvis Cooling Dog Pool dog provides a place for a cool dip on one side and fresh drinking water on the other. Easy to fill, just hook your garden hose to the Cooling Dog Pool connection and turn it on.
This pond is shallower than other ones but the waterfall is very pretty and could be a way to help shower muddy dogs. The flow of water could provide a filter for any of the muck the dogs could drag into the pond