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Lake Pleasant, AZ, adjust for altitude?

Discussion in 'Southwestern Region' started by PBcatfish, Nov 17, 2019.

  1. PBcatfish

    PBcatfish Regular of the Pub

    # of Dives: 500 - 999
    Location: Florida
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    A ScubaBoard Staff Message...

    Posts from the A&I thread that do not relate to that accident have been moved here. We encourage you to continue your discussion and debate in a respectful manner towards one another.


    That's a really deep lake. It's also an altitude dive. A lot of possibilities exist.
     
  2. JohnnyC

    JohnnyC PADI Pro

    # of Dives: I'm a Fish!
    Location: United States
    3,355
    3,700
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    I don't know what Lake Pleasant you are talking about but it's neither. Sure you can hit 230ft at the dam, but recreational diving areas are relatively shallow. Sounds like they were at Vista Point, you can hit 150ft if you swim far enough and the water is high enough.

    Last time I was there on a rebreather I needed a scooter to get far enough out to get any actual depth. That site is used for open water training. Aside from crappy vis all the time, it's hardly more than a swimming pool.

    As for altitude, it's 1700ish feet ASL. Nobody considers that an altitude dive.

    The last death was a technical diver at the dam. I didn't know him personally, but I know some of his friends. I'll withhold my opinions on that one.
     
    maadJurguer, Dark Wolf and Laurie S. like this.
  3. PBcatfish

    PBcatfish Regular of the Pub

    # of Dives: 500 - 999
    Location: Florida
    181
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    Years ago, when I lived there, I recall it being deeper than that. Has the lake level dropped significantly in the last 10 or so years? I do remember seeing rooted trees around 100' down the last time I dove it, so I have to assume that a significant variation in lake level is possible. That aside, I consider 230' to be deep by sport diving standards. I don't normally assume that every diver is a tech guy.

    Also, according to the Navy manual I was using for reference at the time, I was instructed to do SLED calculations for the altitude I encountered there. Perhaps the standards that you work from are different.
     
    markmud likes this.
  4. broncobowsher

    broncobowsher Solo Diver

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    To hit the 230' you pretty much need to be there Memorial day weekend when the lake is the fullest and you will have to find the river bed right by the dam. Possible, but you really have to try to get there.

    The lake does vary a lot during the year. Memorial day through Labor day the water level drops. Varies year to year but 60' drop is possible. The rest of the year they slowly pump water back in. There is a noticeable transition as you go from the new lake level (the '93 dam) to the old lake level (nearly 100 years old). The silt on the bottom really picks up in the old lake bed.

    The location listed is 99% going to be Vista point. Most every dive shop does there check out dives there. It has crowds nearly every weekend. It has a pretty good slope to it and you can reach 100' pretty easy. I avoid it mostly to avoid the crowds. Others it is like a second home.
     
    markmud likes this.
  5. JohnnyC

    JohnnyC PADI Pro

    # of Dives: I'm a Fish!
    Location: United States
    3,355
    3,700
    113


    A ScubaBoard Staff Message...

    Posts from the A&I thread that do not relaye to that accident have been moved here. We encourage you to continue your discussion and debate in a tespectful manner towards one another.


    The water level does vary, 40 or 50 feet or so. Regardless, where they were diving is shallow, benign, and easy enough that everyone does open water checkout dives there.. It could be 3000ft deep and it wouldn't be relevant to the incident. That being said, we certainly have different definitions of "really deep."

    The Navy doesn't even require altitude corrections until 300m and that's only if you're diving deeper than something like 45m? Difference between 1000ft and 1700ft is nothing in terms of pressure, and nobody I know dives at Lake Pleasant with any sort of altitude correction. Standards are irrelevant, nobody dives it like an actual altitude dive.

    Neither is relevant to the incident in question unfortunately. Back channel seems to point to medical.
     
  6. maadJurguer

    maadJurguer Nassau Grouper

    # of Dives: 200 - 499
    Location: Flagstaff AZ
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    No one around here (that I know of) treats Pleasant as an altitude dive.
     
  7. diversteve

    diversteve Technical Admin

    # of Dives: I'm a Fish!
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    Not that it matters but Lake Pleasant is actually at 1700' elevation when mostly full.
     
  8. PBcatfish

    PBcatfish Regular of the Pub

    # of Dives: 500 - 999
    Location: Florida
    181
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    I believe that to get in & out of Lake Pleasant, you need to drive though higher elevations. If you plan to camp at the water's edge after diving, then 1,700' may be your dive altitude. If you drive home after diving, then higher elevations may need to be considered.
     
  9. JohnnyC

    JohnnyC PADI Pro

    # of Dives: I'm a Fish!
    Location: United States
    3,355
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    The elevation at Lake Pleasant is entirely irrelevant. Both for this incident, and in general. It was not a factor in this incident, and the small change in elevation is irrelevant in general considering the elevation of all of the surrounding areas is anywhere from 1200-1700 ft anyway. You have to go out west to get below 1000ft, and gotta go way south to get higher than 2000ft. And all of these changes are over a very significant area. The change in pressure is MINUSCULE, both at the dive site, getting to and from the dive site, as well as the surrounding areas.

    It's not Everest and it's not the Rockies. You can believe what you want, that doesn't make it true.
     
    infieldg and sunnyboy like this.
  10. maadJurguer

    maadJurguer Nassau Grouper

    # of Dives: 200 - 499
    Location: Flagstaff AZ
    79
    67
    18
    Yeah, no. Most folks are coming from PHX, so they're dropping in elevation after the dive at Pleasant. Now...if I were coming from Flagstaff (7000 ASL) and diving Pleasant...and wanting to return to FLG...then yes, that would be an issue.
     

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