Hello, Patricia.
I'm no Stimmel expert, but the first thing I noticed was the signature, "George Stimmel". If you search "stimmel' on this site, you'll find a couple of discussions - usually relating to local scenes of his.
With one exception, the signatures were all "G. Stimmel", followed by a two-digit year. The exception was one that said, "Geo. Stimmel", but none of them said "George Stimmel".
I looked in Google Images and found a variety of signatures, including a couple of "George Stimmel"s - a sig that seems to only appear on landscape/scenery watercolors like yours. I have no idea where your scene is located.
You can do online searches for galleries that sell his work - maybe they can help you.
I sold a Stimmel on eBay and got around $150. I've seen the same image get zero bids when priced under $100...........and that's for a highly-recognizable local scene.