There was a power plant that was built in their main grazing area. The constant traffic plus the loss of habitat caused them to move up north.
When my mom was still alive we used to walk together. I refused to let her walk by herself. One day we were on our way home and pretty close to our property when we both watched a mountain lion slink across the road (from our property) and down to the river. It was the most beautiful and terrifying thing I've ever seen. We have bears that go after our trash too. Damn things.