What's with Blue Hole????

[scubajoh44]

So basically the Hole will be good diving till June? Thought they were gonna be dredging midweek everyweek.......?
Jo

 

[DandyDon]

So basically the Hole will be good diving till June? Thought they were gonna be dredging midweek everyweek.......?
Jo

Looks like the plan is to resume in June, but allow diving on weekends. Might be murky, but it has a good turnover of water.

Poor crawdads....

 

[amascuba]

Based on the santarosanm.org website the water completely recycles in 6 hours.

 

[Divedoggie]

Thats based on 3000gpm flow, which may have been true before the last few years of drought conditions and low aquafers.
I would be willing to bet the flow is now closer to 1500gpm which would recycle every 12 hours.

Hopefully, all of the snow that the mountains received this winter will translate into more ground water, and more productive flow this summer and in the future.

 

[scubajoh44]

I'll have to make at least one more trip before June then! Thanks for the tips!

 

[RonFrank]

Thats based on 3000gpm flow, which may have been true before the last few years of drought conditions and low aquafers.
I would be willing to bet the flow is now closer to 1500gpm which would recycle every 12 hours.

I've heard reports from 1000gpm to 1500gpm, and then of course the reported 3000gpm that is what it has been in the past. I have no clue who is right, but I agree that 3000gpm is likley no longer true. And less so after I put a giagantic piece of bubble gum over the grill! Was that wrong?

IMO the #1 thing to increase the vis is for people to stay off the bottom!! Not sure why that is so hard....

 

[Capnsnott]

From my observations and discussions with a city guy. The chamber that collapsed down deep may have started a chain reaction worry. I think they are trying to get some of the weight off the bottom to keep the main floor from going down. When I was doing a night dive last year, you could see cracks forming 20-30' back in under the floor. If you hung upside down and shined an HID light under the walls, you could see some chambers that had opened up way back in. If they pull out 5-6' of the floor sediment, there will be at least two rooms to swim back into. We also noticed that the depth by the grate had deepened by 2' in a years time. If the schematic drawing of the old magma chamber complex is correct, the roof of the 320' deep lower chamber may have been the one that collapsed. The hole could actually become deeper than Rock Lake...... I never heard if anyone found a bottom to the lower magma chamber.
If anyone has a phone number for the Corps of Engineers I would love to talk to one of their Geologists.
asta
Greg

 

[RonFrank]

Thats based on 3000gpm flow, which may have been true before the last few years of drought conditions and low aquafers.
I would be willing to bet the flow is now closer to 1500gpm which would recycle every 12 hours.

I've heard reports from 1000gpm to 1500gpm, and then of course the reported 3000gpm that is what it has been in the past. I have no clue who is right, but I agree that 3000gpm is likley no longer true. And less so after I put a giagantic peice of bubble gum over the grill! Was that wrong?

IMO the #1 thing to increase the vis is for people to stay off the bottom!! Not sure why that is so hard....

 

[roakey]

IMO the #1 thing to increase the vis is for people to stay off the bottom!! Not sure why that is so hard....

I disagree. I used to think this, but observations over the years have led me to believe that it's the diver's that are diving the periphery at the bottom that cause the majority of the problem. This is because BH is wider at the bottom than at the top, so their bubbles roll up the sides and dislodge all the silt along the ledges all the way up, especially the organic stuff right at the top which rains down into the hole.

I don't see much "chocolate milk" silt (like I see in caves) in the hole that would be caused by the bottom muck being stirred up as much as I see tiny organic particles floating about.

Given, lots of bottom stuff is stirred up which shouldn't be, but unless it's right next to the grate, it has a tendency to stay near the bottom rather than rise through the water column.

Which of course means there's no solution to the problem, because once a diver has advanced beyond the "what's my pressure, what's my depth, where's my buddy" stage of awareness, the fun of the hole is to poke around the nooks and crannies of its sides, which causes the bubbles to be a problem.

Oh well.

Oh, and a story on why I suddenly changed my mind as to the bubbles around the sides being the problem:

Years ago a couple friends and I were experimenting with a "deco dome" (fancy name for an upside down cattle trough ) near the bottom of the hole -- it was put upside down under a ledge and filled with air from an AL80. We were seeing how hard it would be to eat and talk in it (turned out to be too small for two divers to talk without considerable effort, which means we learned something ).

We put the dome in Saturday morning and left it there until late Sunday morning. To remove it, I unscrewed the drain plug and the air roared out -- up the side of the 'hole.

In less than 5 minutes the visibility, which wasn't great to begin with being Sunday, was cut in half.

People were surfacing and commenting to their buddies. "geez, what happened? The viz just became horrible!"

We sheepishly pulled the dome out, threw it in the truck and boogied out of there, swearing that if we ever brought it back, we'd wait until Sunday evening to pull it, or find a way to divert the air further out into the water column so it wouldn't touch the sides on its ascent.

Guilty as charged

Roak

 

[RonFrank]

I disagree. I used to think this, but observations over the years have led me to believe that it's the diver's that are diving the periphery at the bottom that cause the majority of the problem. This is because BH is wider at the bottom than at the top, so their bubbles roll up the sides and dislodge all the silt along the ledges all the way up, especially the organic stuff right at the top which rains down into the hole.

You maybe right, in which case then I'm a major cause of the decreased vis, as I most always hit the bottom, and spiral up.

Funny story... just keep your bubble dome out of there on the Third Sunday of the month!