Did a load of laundry and the bathtubs backed up with water. Went outside to check the clean out and when I opened lid, water came rushing out. Can I fix this? Should I call County or a plumber?

You have a blockage in the main sewer line between the clean out and the street. Rent a power plumbing snake and snake from the clean out to the street.

PH3:

Harold told you what was happening and how to fix it... I just wanted to add that you should call the county sewer department and at least ask if this is something they can down and clear for you.

Some towns, like mine, will clear main drain lines when called during regular working hours for no charge... MOST TOWNS WILL NOT DO THIS!! But some will.. worth a quick call to ask.

Here is a pic. Of the cable machine Harold suggested renting... Good luck... Mark