Just saying - A couple of things you can do on your own before you go to a shop...
The heater valve is on the passenger side (same side the green colored snow in your picture).
It's notorious for leaking, and then spreading the coolant to strange locations - due to the coolant flowing on the bottom of the heater hoses and eventually dripping down far from where the leak started...
Suggest that you not only visually checked the heater valve for coolant & as well as crusted coolant
, but also wrap your hand around it and see it it's wet.
You can also check the heater hose connections on the firewall, where the hoses meet up & connect with the heater core.
Also, make a reference line on your overflow tank and watch the level.
Without a reference line, it's really hard to follow the "progress" of a small leak
Hope that helps -