The dog is barking because it's feeling neglected, frustrated, and unable to express itself in any other manner. If you do go the firearms route, be sure to aim at the owner, not the dog.
I would start by suggesting obedience school to the owner. Do not start out confrontational. If the owner says the dog failed, remind him or her that the dog isn't the one that passes or fails obedience school - the owner is.
Also, do not squirt a dog with anything. You will only antagonize the poor beast and cause it to bark even more, and carry a big chip on its shoulder towards you.
I suppose the police may be your last resort, but if the thing is definitely neglected, call the SPCA (Society for the Prevention of Cruelty to Animals). They are my charity of choice, and I assume they are in the States as well as Canada. If nothing else, the owner will be watched more closely.
I empathize with your situation, but frankly, I'm more sympathetic towards the dog. Dogs are social animals - more so than humans, and a dog is a family member. Just like how sometimes I wish I could tie grandpa out back sometimes, but I don't because he's a family member.
Regards,
Craig