The rule is as clear as any statement in the English language could possibly be. "Wetsuits are allowed for all athletes if the water is 78 degrees Fahrenheit or colder." Why people keep coming back to some supposed ambiguity in the rule if the water was 78-84 is beyond my comprehension. There's the rule. Live with it. BTW, if you go to weatherunderground their marine weather for Cambridge yesterday indicated a water temp of 79.5 degrees.
As for implementation and enforcement, USAT rules and procedures place this in the hands of the head referee, not the RD. See competitive rule 4.6. That rule is further elaborated into how it is implemented in the USAT officials manual. The relevant portion is excerpted below:
Measuring Water Temperature
The Head Referee, or his/her designee, will measure the temperature of the water at the swim venue the day before the event. The temperature should be measured as close to the actual next day start time of the event as logically possible. Changing weather conditions may dictate the requirement for an additional measurement on race morning. This will be at the discretion of the Head Referee.
A Fahrenheit or Centigrade thermometer, approved by the Head Referee or his/her agent, will be used to measure the water temperature. The recommended model is found at http://www.professionalequipment.com/...te-4146/thermometer/
Temperature should be measured, at a depth of not less than 6 inches, nor more than 24, and at a distance of at least 60 from shore. Understanding that all swim venues will be different, it is the responsibility of the Head Referee to devise a method to measure the water temperature in a manner that will stand the test of the Reasonable Man (that the reasonable person would agree that the method used was sound and will give the Head Referee a reasonably accurate and representative water temperature). Section 4.6 of the Competitive Rules suggests a method, which may or may not be practicable.
The water temperature will be posted at the packet pickup site, and will be announced at any pre-race meetings. It will also be posted at the race site on race day. If changing weather condition necessitates a race day measurement, participants should be told that they should be prepared to bring wet suits to the race site on race morning pending a measurement.
Understanding that a boat may not be available, the Head Referee may decide to measure at or near the shoreline. The coldest measurement will be in shallow water near dawn. Only the Head Referee is delegated the authority to modify the guidelines for measurement. There can be no modification of the temperature requirements for wetsuit usage.
So as you can see, there is some room for discretion in how the referee tests the water, and how that determination is presented to the athletes. Although I was not there, it seems that the biggest beef that some folks have is that the announcement was not made the prior day. That's a pretty small whine in the big scheme of things.
What irritates me is that some seek to impugn the RD (who has been at this a long time) and the officials, who it seems to me tried to do everything they could to get it right, even at the cost of annoying a few swimmers who seem a bit attached to their neoprene.
Glad everyone made it home after what sounds like a tough day in the heat.