Jackson Blue conditions?

[TracyN]

Nothing to see here. Please move along.

Lol!!!

[diverdarren]

Thanks, guys. Just wanted to hear from somebody that had been lately. Looks like I'll be calling Edd 's in the morning!

[TracyN]

Have you been golf ball diving again Rob? Don't you just hate it when your golf balls land in a sinkhole.

[Captain Bil]

We dove JB on 10/9 and 10/10. Viz was crystal clear, and the flow was down. On both days we easily swam (single stage) to King's Canyon.

[jason]

As for Hole in the Wall, my theory is conditions there are more affected by the Indian Springs golf course than by rain intrusion in the sink hole or the other entrance. The golf course has to start pumping more fertilizer into the greens and fairways in the winter to keep it looking nice and that all affects the visibility in Hole. This is especially apparent in certain areas of Hole and looking at the overlay in comparison to those areas and the golf course, they are pretty close. Of course, this could be affects of what they did 17 years ago. I'm not sure how the seepage works and if it is close to 17 years on the mark or varies by a few months. But I have also seen Hole run crystal clear throughout the year and have bad visibility during the summer. So it probably varies.

While I don't have a lot of experience in the Mill Pond, my guess is that the primary reason viz deteriorates in winter in normal years is because there is little or no gradient in water level between the lake and the water table above the cave, which allows the increased density of colder lake water to push lake water into the cave system (where water is warmer and has lower density). Years where the viz is bad in summer, the lake is probably high relative to the water table and years where the viz remains clear in winter are probably where the water table is high relative to the lake.

[RN]

Jason, I could see where that could be the case. Except it doesn't happen in the other caves on the Mill Pond. Twin Cave's entrance is in the floor of the pond away from the bank, unlike Hole in the Wall, and visibility in there is pretty constant year round.

[jason]

Jason, I could see where that could be the case. Except it doesn't happen in the other caves on the Mill Pond. Twin Cave's entrance is in the floor of the pond away from the bank, unlike Hole in the Wall, and visibility in there is pretty constant year round.

The elevation of the entrance doesn't really matter all that much - but rather the elevation of the water table in the springshed. If there is perceptible water flow in a cave, then the water table in the spring shed is sufficiently high that temperature-driven density differences won't be able to cause lake water to sink into the cave. JB obviously has water flow. According to conditions reports (because I've not personally been to either of these caves), Twin seems to have very low flow whereas HITW has no flow. As a result, flow would prevent density-driven flow into JB and Twin but not HITW. In any case, I could easily bring up a bunch of low-cost temperature loggers and install them in the lake and various parts of caves if folks were really interested.

[Kelly Jessop]

While I don't have a lot of experience in the Mill Pond, my guess is that the primary reason viz deteriorates in winter in normal years is because there is little or no gradient in water level between the lake and the water table above the cave, which allows the increased density of colder lake water to push lake water into the cave system (where water is warmer and has lower density). Years where the viz is bad in summer, the lake is probably high relative to the water table and years where the viz remains clear in winter are probably where the water table is high relative to the lake.

Would be an interesting study. I think some of your hypotheses are good,because when a "turn over" does occur, I have seen domes in HITW have warm,clear spring water, and the floor/mid-column area have cold water with poor visibility.

Rob brings up a good point regarding the gold course. Has the recharge area for HITW ever been mapped out, and would surface nutrients from the gold course be part of this?

[jason]

Would be an interesting study. I think some of your hypotheses are good,because when a "turn over" does occur, I have seen domes in HITW have warm,clear spring water, and the floor/mid-column area have cold water with poor visibility.

Rob brings up a good point regarding the gold course. Has the recharge area for HITW ever been mapped out, and would surface nutrients from the gold course be part of this?

I think the primary reason that nitrates are unlikely to be the cause is the seasonality of the visibility decline.

[RN]

The elevation of the entrance doesn't really matter all that much - but rather the elevation of the water table in the springshed. If there is perceptible water flow in a cave, then the water table in the spring shed is sufficiently high that temperature-driven density differences won't be able to cause lake water to sink into the cave. JB obviously has water flow. According to conditions reports (because I've not personally been to either of these caves), Twin seems to have very low flow whereas HITW has no flow. As a result, flow would prevent density-driven flow into JB and Twin but not HITW. In any case, I could easily bring up a bunch of low-cost temperature loggers and install them in the lake and various parts of caves if folks were really interested.

Actually, Hole and Twin are about equal in flow. I've felt higher flow in Hole on occasion. One thing about Hole is there are 2 main passages that both dump out of the same hole to the pond. The flow from each side is different at times. I've seen the flow from one side overpower the flow from the other and it gives the appearance of a siphon on one side for several hundred feet until the opposing flows equalize. This happens from one side or the other. Not sure why it's not consistent. I've just witnessed that it's not.

I would love to get data on this. I think the state would also be very interested. I can help you set these up and we can even look at overlays to decide where in the systems these loggers would best be positioned.