Santa Rosa Trip report--Sept. 20-22

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boulderjohn

Technical Instructor
Scuba Instructor
Divemaster
Messages
31,643
Reaction score
29,778
Location
Boulder, CO
# of dives
1000 - 2499
To be fully transparent, the purpose of this trip report is to try to spur more interest in trips to a fun diving area that appears to be lagging in comparison to past years.
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I was working with a student on Advanced Nitrox and Decompression Procedures, and we could not leave until Saturday morning. We arrived at the Blue Hole in the afternoon, and it was great to see old friends in Justin's group when we arrived. The Blue Hole is looking good. The removal of the old snorkel over the cave entrance seems to have done wonders for the general health and visibility of the system. I was there a couple of months ago, and the grate over the cave was covering the ground on all sides. That is not true now. There is a growing hole on the side away from the wall. I don't know if it is erosion or intentional actions of people wanting to get past the grate. If it is intentional, it won't do much good. That grate was placed by one of the most experienced cave diving teams in the world after they were unable to get past the large rocks that were placed in the opening years ago to prevent access. The cave beyond those rocks is quite a serious affair, and no one without proper training should even think about it. My student and I did some preliminary dives to get some of the more basic requirements out of the way and went home after dark to get ready for the more serious diving on Sunday.

On Sunday we were out at Rock Lake, and it was clear that I was not the only one who had not been there for a while. The grass was deep all around the entrance. It did not look like anyone had been there for quite some time. The lack of recent activity was also evident on the dives. The top of the lake is rimmed with vegetation that drops very tiny leaves as they die. This creates the characteristic landscape of the lake. As the vegetated upper slope changes abruptly to a cliff plummeting to the depths below, the vegetation hangs over the edge in a way that makes you wonder about the hanging gardens of Babylon. Below that the pruple-black walls are interrupted by ledges on which this fine beige silt collects, often with purple selenite gypsum crystals poking through. That was not what I saw this weekend, though. That fine, powdery silt had even collected on the rough edges of the walls, turning the dominant color from purple-black to beige. Swimming within 5 feet of the wall, as you usually do, is all it takes to create the mild current that shakes that dust from its precarious hold and drops it to the depths below. At one point I came upon a length of cave line hanging from above. It was covered with that silt. I moved it gently, and the silt came off, staying in place in the shape of the line like a ghost until it slowly began to drop.

September is usually the month for the warmest water there in the upper level, which too often means a thick algae bloom over the top of a thermocline. Swimming beneath the thermocline is like flying a plane beneath a cloud layer. This year was different. Yes, there was a warm water layer and algae bloom, but it was very mild. The visibility was about 25 feet in the middle of it, and much better, of course, below it. The water below the thermocline was even fairly warm. I got a balmy 63° F.

The two of us had the place to ourselves, and you cannot imagine a more serene setting for your diving. The weather on Sunday was beautiful--sunny and calm without being too hot. Monday brought a rare cloudy day, which was welcome for surface intervals in a dry suit. There was an occasional mist on our last dive, and it was just starting to rain lightly when we finally pulled out at the end of three great days in Santa Rosa.

I cannot end this without once again praising Stella, the queen of Santa Rosa. We were done late on Sunday. She had told me to call her when we needed her, and she came as soon as she could to fill our tanks for Monday. Without her and her unbelievable willingness to do whatever it takes to help people with their dives, it would not be possible to do the things we do there.
 
Sounds like a nice trip. I have a friend that wants to make a trip down between now and December. Seems like it would be a waste to go down and not hit up Rock Lake. Would you be up for another trip down again this fall?
 
Where is Rock lake? I know about BH and Perch, but not Rock.
 
Sounds like a nice trip. I have a friend that wants to make a trip down between now and December. Seems like it would be a waste to go down and not hit up Rock Lake. Would you be up for another trip down again this fall?
I am looking at either the last weekend in October or the first weekend in November. Interested?

Where is Rock lake? I know about BH and Perch, but not Rock.
Rock Lake is one of my favorite diving experiences, which may or may not speak volumes about me.

It is located only a couple of miles (if that) from the Blue Hole as the crow flies. It is on private property, and you can only get access if you are working with one of a handful of technical instructors who have permission to go there. I am happily one of them.

The Blue Hole is a sinkhole, 60 feet across at the top and 120 feet across at the bottom. It is 85 feet deep by the cave entrance, but more like 70 feet deep where the diving is done. It is within the city limits, with a nice building with bathrooms and showers. The area around the top is concrete and well-maintained wall.

Rock Lake is also a sinkhole. It is 300-400 feet across at the top, depending upon whether you are looking east-west or north-south. I have no idea how wide it is at the bottom, and I don't think anyone else does, either. There is great undercutting on the walls, but I don't know anyone who has a good idea how much. It is around 300 feet deep at its max, I think, although depending upon the debris cone shape, it is much less in some areas. I think. It is a hole in the prairie. The only sign of humanity nearby is a tin shed, which is falling apart, and some tables made by divers to make donning gear easier. There is also a set of steps leading to the water on the East side. It has the typical sinkhole hourglass shape, with sloping walls around the perimeter filled with vegetation. It then plummets to the depths below, with the vegetation hanging down over the edge. The walls are covered with what my untutored mind takes to be a blue-black variety of goethite. It has ledges where the falling organic débris from the vegetation forms a very fine loose beige silt, and purple selenite gypsum crystals poke through in places. It has a very rare variety of fresh water sponge in places. On one dive a couple of years ago, a couple of us found some minuscule amphipods living in that fine silt on a ledge at 150 feet. We never found them again, despite looking hard for them on many subsequent dives. Even as a student, you are required to have at least AOW certification.

Sound good?
 
Great write-up for black lake. I had heard about it, but forgot about it being private. I guess thats why I never followed through with finding it's location.
 
I am interested. Current I don't have anything scheduled for either weekend.
 
See my newer announcement
 

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