Just to play Devil's advocate in regard to the choice of site and the conditions ...
Key questions:
1- Why was this class conducted in this location - a relatively shallow river with limited visibility and known currents? Virtually all other Open Water classes at the shop were conducted at a popular quarry just 1 hour away (from this location) in Pennsylvania (Dutch Springs), and other, even closer locations exist which would be more appropriate to teach an Open Water class.
As was mentioned Dutch Springs is closed for the season with the exception of a couple instructor weekends and special events such as the New Year's Eve day dive. It is true that instructors can request to get students into Dutch Springs after the season, but such requests must be made well in advance and aren't always granted due to staff scheduling, maintenance, or the group size wouldn't warrant the cost of opening for the day. Sometimes, instructors who are heavily supportive of Dutch, behave professionally, have a track record of getting their people out of the facility on time, or do favors for Dutch may get into Dutch with a small group.
Divers who dive the Delaware River often see a variety of conditions regarding visibility and current. The visibility can be quite good and the current is most often mild at the Delaware Water Gap. Unless the river is high and really moving (conditions adverse to diving) you can avoid current by staying near the river bank. The train wreck, for example, rarely has a current unless you swim toward the center of the river.
I'd be more concerned with depths of 114 feet at Narrowsburg, NY or 55 feet on the bottom of the river at the train wreck than with "shallow water" since every foot of depth increases the risk potential. Open water courses are conducted in areas along the east coast with worse visibility, current, surge, and strong tidal changes.
2- What was the justification for conducting an Open Water class in a single dive, and how was that even possible? I admittedly don't know NAUI's standards, but PADI requires a minimum of 4 dives.
I would venture a guess that the reason would be due to the cold diving conditions. Every cold water and winter conditions diver knows the hardest thing to do when diving in the cold is to suit up and go back in. I've seen many instructional dives last just 20 minutes at Dutch Springs. If the instructor planned to do 4 dives at 20 minutes each, then that would be 80 minutes of bottom time. In this case, the instructor probably planned to complete all skills in one dive that lasted about 80 minutes. This would allow the group to deal with being wet and cold once then get dry and warm. The students would lose 4 practice descents/ascents and lose time to rest, but the minimum skill requirements could still be performed.
I don't agree with it. Not the best scenario by far, but I know several instructors who could teach more in one dive than most who are running the typical class. I don't know the instructor and I can't speak for his teaching abilities, but if it had to be done, the bottom time could be the same as that of 4 dives. My concern would be lost opportunities for descent/ascent practice, breaking down and assembling equipment, and loss of educational opportunities between dives. However, even if the instructor planned 4 dives, the accident could have occurred on dive #1.
3- How does a PADI and NAUI Course Director, with Technical instructor experience, over 5000 dives and several hundred student certifications, with the help of a Dive Master, fail to maintain a group of two students? A husband and wife, no less, who will naturally want to stay together.
I once ran a refresher for a husband and wife who were very much in love. You'd need a crowbar to separate them topside, but underwater was another story. He liked to sink into the abyss. She liked to hit the button that saves. They tended to do this at the same time. My DM really earned his poor pay that day! Instructors lose students with 50 feet of visibility at Dutch. In 15, 10 or 5 feet of visibility sometimes 3 seconds of distraction can split a team. It happens when we assume someone will behave a certain way. For example, you see one buddy engrossed in looking for arrowheads on the bottom kneeling still. You take 3 seconds to adjust a piece of equipment on another student - poof! You drift a foot one way, the student fins 2 feet another, if you don't catch it one more fin kick and there's 5 feet. High visibility colors help. A DM may get used to sticking with the weaker student and still remain buddied with that student if you adjust gear. The DM may also naturally want to help you adjust something or focus on what you are doing and take eyes off the other diver just long enough for separation to occur. A pretty common scenario for a DM to lose total awareness would be having a dive flag line snag on his or her own equipment. The DM focuses on clearing the entanglement rather than being able to multi-task and maintain team while performing a self-fix. Sometimes you are at the top of your game. Sometimes you are not. Cold water makes instructors and DM's lethargic as well. Reaction times are dulled. Dive pros can become more passive. In warm water, I am more participatory and "hand's on" in my classes. In cold water, I tend to observe more and signal or demonstrate less often. Basically, in cold water you are more likely to drop the ball much like NFL players do after October.
4- Assuming (and I'm speculating) the necessity to get certified in December, in the North East, was because the couple had a vacation planned, why wasn't a standard referral given so they could have completed their training in better conditions?
I often have students who believe they need to take a class in the worst case conditions in which they will dive. It takes some convincing to get them to want to dive in warmer, calmer water that is more conducive to learning and safety. Maybe they wanted to learn to dive in lower visibility with currents? Maybe they didn't want to lose time on vacation to training? Maybe the instructor needed money to pay bills and convinced them it was a good way to learn?
While this could be a tragic case of a diver panicking or suffering from some unknown health-related issue, it's hard to see how the conditions didn't exacerbate the situation. I can only hope the tragic loss of such a young individual leads to some improvement in train standards, be that on the part of certifying agencies apparently willing to bend their own rules, or instructors seeking the bending of rules for primarily reasons of convenience and/or profit.
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While I wouldn't want to teach a class in such conditions, 40 F water is not an uncommon temperature for open water courses in many northern waters. The cold water could certainly exacerbate many situations. Accidents happen in ideal conditions. Safe dives are made in rough conditions. The farther we get from 1 foot of water in 86 F in 200+ visibility in zero current at the Equator, the more we begin to assume risk. Cold creates a greater potential for accident. We can keep creating standards such as no training below 50 F. Then when an accident happens the standard could move to 60 F. Then, 70 once 60 becomes "cold" etc. We can do the same for visibility, wave heights, etc. Then, when accidents still happen in our Utopian dive world, it will be time to take away the next cause of accident or injury.
The most likely scenario is that an instructor looked at the weather and conditions, looked at the ability of the students, and looked at his bank account and decided to run a class truly believing everything would be fine. He probably wanted to make their dive as comfortable as possible in winter conditions and asked the agency to allow him to complete all skills in one long dive. The agency probably thought of how miserable the students would be and wanted to make the instructor happy and not have him cross-over in these tough economic times and approved one dive based upon the amount of training in the pool and class they were told the students had. The students ultimately decided to dive even though they could have said, "No way." Everyone, I'm sure, expected everything to be fine because most times they do go fine. Everyone probably wanted to have a good time. Unfortunately, something went wrong. A fatal accident happened in shallow water. Accidents are often a chain of events. In this case the accident chain pertains to several of the factors you mentioned. Yet, around the world many divers are successfully trained in similar conditions which is why I wouldn't call the conditions "unsafe."
The conditions were certainly part of the accident chain.
