One of many trip reports by Alan Silverstein.
Last update: March 11, 2008
From: Alan Silverstein <firstname.lastname@example.org> Date: 16 Aug 2004 13:37:17 -0600 Subject: Re: [Lake_Powell_2000] Love to hear the trip reports To: Lake_Powell_2000@yahoogroups.com
...I just got back from a week (7 nights) leading a trip on my 62' private houseboat out of Bullfrog. I set a lot of personal records by allowing a far-and-away biggest crew ever: 18 people, including 6 in the 9-18 age range. It was surprisingly fun and uneventful, as the crew were all great folks, very easygoing and helpful. We had two ski boats and I delegated tasks like crazy. Still I found it very busy for me, and I am now quite tired, back at home, digging out.
On my trips we usually move the boat almost daily, and we did that again; six mooring spots in seven nights. I like to get around and see a lot of the canyons. Also learning how to clip anchor lines to themselves around boulders and avoid anchors => much easier.
Later we found the sandy beach at the end of Fiftymile Canyon (Escalante) occupied (no surprise), so went to near the end of Willow Creek Canyon, just a couple turns past Bishop. Shallow but pretty. Kayaked around the corner and then slogged deep mud and quicksand to hike up and around the back of the hugest overall cave on the lake -- the "island cave" -- where we used to motor around the island when the lake was full. Rather desolate now above lake level.
Next I took the houseboat into Cathedral in the Desert (Clear Creek Canyon) for the third time. More and more impressive. Now 25' deep in the middle and 14' at the waterfall, which is 25-30' high above water. Ropes still there, but no one could climb the sheer wall up and out, the first 10' or so were too steep. (Well actually Micah made it above the crux once.) I dove twice to the silt fan at the base of the falls.
Moored at cove on the downstream side of Jackass Bench -- less than a mile up from Hole in the Rock.
Took the houseboat down to the mouth of the San Juan and decided the holding tank was holding out OK (wrong). Sent most of the crew by ski boats to Dangling Rope Marina (16 miles downstream) for ice cream and to buy more ice, etc. Motored the houseboat 20 miles up the San Juan to Piute Bay. Saw 3-4 other boats there. Still plenty huge and quiet. Lots of water sports. Kayaked across the bay myself... Neat bubbles coming up (methane? CO2?) in the middle of the bay.
Floated naked in pitch darkness under the stars watching the peak of the Perseid meteor shower... Nice.
Later took a ski boat up the San Juan River until it literally stuck in the goop, with 1-2" of clear water flowing over what looked like river but was really slime. Wide, gently flowing, no obvious "end" in sight. This was around from the Great Bend, but still about 4.5 miles GPS direct from Zahn Bay.
Wind came up strong later this night, and the next two also... Dang it. But it helped reduce the smell from the now obviously nearly full holding tank... Oops. Too late to deal with it that evening.
My GPS logged 178 miles (!) on the houseboat in about 32 hours. More records. In retrospect we should have taken the boat to Dangling Rope on Wednesday and never gone as far as Piute, oh well.
From: Alan Silverstein <email@example.com> Date: 17 Aug 2004 13:25:54 -0600 Subject: post-Powell info on Gregory Natural Bridge To: (person at Natural Arch and Bridge Society)
Last Tuesday (August 10) I visited Fiftymile Canyon again. I was all alone for two hours with a kayak (ski boat dropoff). I dove four times to the underside roof of Gregory Natural Bridge and got a good measurement, 28'0" down plus or minus a few inches, but this might be the "upper roof" angling up from the real arch. I saw the latter, but could not get deep enough to see through it. This underwater bridge is massive.
I took the measurement by tying a light, weighted line to the kayak, pulling it snug down at the edge of the roof, holding the spot until surfacing, tying a knot, and later measuring it with a 100' tape. I adjusted for the small distance, about 5", from the knot on the kayak to the water level. The line itself was at a slight angle, not vertical, since the roof of the arch is concave, but I don't think this mattered much.
On the fourth dive I double-checked the knot, then forced myself a bit deeper below the sharp roof edge, to see to my chagrin the arch itself a bit lower still. I only had a moment, and surfaced gasping and a bit dizzy -- so I quit diving at that point.
Anyway, the lake level... Dropping fast. They report it at midnight and it's ambiguous, one source is a day ahead of the other. One source says 3577.38' on Aug 10, the other on Aug 11, so I conclude that must be the night of Aug 10. It was 3577.64' previously. So noontime Aug 10, estimate 3577.5', deduct 28' (or a bit less) to get 3549.5' (or a bit more) for the underside of the sharp roof, even though the high point of the arch itself is perhaps a bit lower.
I also dragged the kayak up and down to the "back pool" (now connected only by the bridge) to photo and dive a few times on the upstream side. I didn't even try to get deep enough to see through it, just watched for signs of light coming through, and did see that on the second dive. The upstream side was slightly away from the sun, also lacked any reference points for the location of the bridge.
I checked the rock on both sides for a way to get to the top of the lintel. No joy. Maybe a long hike in from some other up and out point, but I didn't have time. I did take another set of photos (I'll get them to you eventually) we could use for extrapolation. Clearly the top is only a bit below the high water line, say 3690'. That would make the bridge's thickness roughly 3690 - 3550 = 140', and the height based on May, no more than 90-35 = 55'.
Unfortunately I did not bring a long enough line for a depth measurement... Sigh. I only had 50' (measured at 46'+ with knots) and it didn't reach. However, the silt level on the bottom is undoubtedly many feet now anyway.