We have a dog

So, I come home on Sat night, and my housemate tells me there's a dog in the backyard. What?! So, apparently, they came home to a dog in the yard. She's very sweet, but big. She looks like a Labrador mix. Her tags said she lives in La Jolla. We've called the number on the tag, and plan to contact the licensing authority to try to get her home. I'm really hoping we can find her family, and I'm open to suggestions. In the meantime, I need to walk the dog.