Hi Amanda,
Lake County, CA is a unique place. Check it out but I believe the current required notice of non renewal for a lease 1yr or linger is 60 days. The lease should automatically switch to a month to month agreement after the expiration of the 1 yr. agreement. Month to month agreements only require 30 days notice. Again check to verify that this information is correct. Do you live locally? The job market is tight here in Lake County right now. Avoiding the occupants from squatting is best addressed with background checks, employment verifications, and references before signing the lease. Turning the management of the rental over to a property manager can relive a lot of these issues. I would be interested in knowing what town the property is in. The quality of available tenant varies drastically depending on the neighborhood. Ultimately, clear communication and expectations handled in a respectful manner can avert any issue. It sounds like they have been paying, maybe talking to them about your concerns can help them better meet your expectations. Then everyone can be grateful for a long-term arrangement.