Here is an observation I had.
I was in DCA yesterday and my daughter and I were walking around the the lagoon and just entering the east side of the WOC viewing area. As we did they tested one of the water cannons in the center of the lagoon about 20-30 yards away from the railing. The shot was at least a hundred feet high and as the water descended, it was pushed by a gentle breeze and absolutely soaked about a 10 yard by 10 yard area of the viewing area right by the rail.
I was thinking holy crap that was a lot of water and it would have come down right on the crowd if they had been there. There was a security guard there and we were discussing the water that had just rained down from the shot and he was telling us how much water comes down during the actual show. He warned me that people in the front section were defiantly going to get absolutely soaked for 20 min.
So let this be a warning to anyone planning on using expensive electronic equipment or for that matter simply dont want to get douced. If it is even the slightest bit breezy there is the very strong chance you will get super drenched and leave sopping wet.