Noticed I had a leak at the pressure reducing valve where the water shut off is and the sprinkler system connects. I have fixed this same thing 5 years ago but today/tonight it is just not working! Guess I am calling a plumber tomorrow morning. I have water but it is still leaking and not sure what I fucked up! Frustrated so having a beer to calm down.
Go snap a photo of the PRV and I'll have a look. It's probably just a back flow valve. If it's leaking from the union you need a new rubber washer. Get me a pic and I'll try to help.