Your guess is right on the money. Those poles are snow markers, plain and simple. I'm up in Minnesota and every hydrant on my street has one, and the ten foot height is not overkill, I promise. What kills hydrants in snow country isn't the fluffy stuff, it's the plow berms. The plow goes by a few times and pushes a wall of dirty slush against the curb that can easily bury a hydrant three or four feet deep, and the pile keeps growing all winter. The marker has to stick up above the final berm in March, not just the first snowfall, hence the height. The barber pole colors are just so it reads against a gray February backdrop from a moving truck, and alot of them get a strip of reflective tape or a little flag on top for night visibility. As for wheather it's a standard, not really, at least nothing I've ever seen. It's a per-town thing handled by the water department or whoever owns the hydrants. Some towns bolt a marker right onto the hydrant bonnet, some put in a standalone pole like you saw, some just paint the hydrant a loud color and call it done. There's no uniform paint scheme either, so a marker in one county can look completly diferent from the next one over. If you're curious about yours, a call to the city water utility will get you an answer. One thing worth knowing now that you're a hydrant owner, sort of: in plenty of towns the expectation is that residents keep the hydrant near thier house accessible over the winter, so when you see your neighbor out shoveling around one with a snow shovel after a storm, that's why. Fire crews hate losing five minutes digging one out with a house burning. And for the antenna jokes above, the hydrants are indeed very well grounded, but nobody's made them sing yet.