I wouldn't think of the Longmot Tri as being sprinty, at least not the portion that I saw. Your wave is determined by your estimated swim time. I'm not sure I understand this logic, but they start the slower people first. The elite people were just finishing their swims as DH and friends were finishing the entire race. So whoever came in last in terms of time was not the last to cross the finish line. This race attracted all sorts. The top finishers were averaging 26 - 28 mph on their Tri bikes. At the same time I saw people riding mountain bikes, and beat up rusted out old cruisers. I saw several competitors that were obese, people I wouldn't expect to see in a triathlon. I think you'd really have to be trying to come in last. I think the elite triathletes might have treated it as a sprint, but not the average recreational people like DH and friends.

Friends I've talked to that have a fear of open water fear it more from a potential drowning hazard rather than an icky water thing. The worst I've heard is a fish touching someone's foot. The Boulder res is open for swimming in the summer, its quite popular. I've never heard of it being a health hazard.