I have been to both Gilboa and Portage. Gilboa gets LOTS more traffic that Portage. In fact Gilboa gets more visitors on any given day than any other quarry I've visited (Haigh, White Star, Blue Springs, Mermet, Joe's Quarry in LaGrange, Fantasy Lake, Lake Rawlings) none of them even come close to the number of people who are at Gilboa most weekends.
As far as this incident goes, there is nothing that suggests this is anything more than a heart attack that happened in the water. Also it said she left the one group to join the other. ***pure speculation ahead*** That suggests she let her dive buddy know she was going with the other group. I've seen this happen many times at the quarry, when you have a group that plans to stay at the airplane and some others that plan to head down the road to the tubes. A diver thinks they can handle the cold, gets about 20 feet beyond the plane and hits the thermocline, and heads back to the plane to join the others who are there. Not saying that this scenario is advised, but I've seen it A LOT. *end speculation*
Gilboa is Deep, Cold, and busy. The first incident this summer was divers who were in over their head. I don't see (nor do I want to see) Mike do anything more to keep untrained divers with out the proper gear out of the deep end. For those who haven't been there, the quarry uses a system of coded wristbands to identify students, BOW, AOW and instructors. To dive off the deep dock you are supposed to file a deep plan which is reviewed by the staff to assure a diver has a reasonable plan, and the proper equipment. Many divers either break this rule, or just go in off of one of the shallow docks and swim over the edge.
Van's death was ruled a heart attack.
This incident it is too early and not enough info to make any speculation on COD.