Canadian lifeguard SBer checking in. Just some points I want to throw out here:
* coverage zone and lifeguard

atron ratios for waterparks is not the same as pool. If it is the same as when I guarded wave pools back 6 years ago, the ratio is 1:250 but it can vary between organizations (to increase the ratio to favour guards, never decrease). Maybe that's why one of the guards quoted 1000 patrons (5 guards on duty)? Also coverage is usually a series of overlapping arcs (so there are always 2 guards potentially watching an area).
* It is recommended by the National Lifeguard Service that children must be at least 7 years old to be able to swim by themselves. Any younger (or if you question the patron's ability to swim) and they must perform a swim test (usually a width of the pool without stopping but I make them do 2 widths cause I'm an A-hole like that...). I am not sure if this is actual law per se, but it is taught in all the lifeguarding classes.
* Canadian Lifeguards are not required to seek assistance from off-duty trained professionals and to be honest also encouraged not to since it will screw up protocol and the whole liability thing comes in. It is my humble opinion that they did the right thing to turn down assistance from nurses/doctors. There is nothing they would have done extra in that situation that the lifeguards wouldn't have (assuming that all 5 guards were trained correctly).
* All guards must have a
minimum cert of standard first aid and CPR level C. There is no EMT level course offered for lifeguarding, however, AED and airway management are additional courses that can be taken. Red Cross and St. John's also offer equivalents to EMT but are not required to work as a lifeguard (unless the employer wants it). I do not know what cert level was required for the waterpark being discussed here.
My opinion: blaming patrons wearing a mask is a poor excuse. Although I remember a several occasions that my teammates and I jumped in on kids like that (but they had snorkels). Better to be vigilant than complacent.
ninja edit - ^^^^yea, I agree with freediver on the mask thing.^^^^
fake ninja edit: rule of 30secs scanning applies for waterpark guards, but encourage to do it in 15secs.