Lakes in the Hill Country

[ReefHound]

Few people really want to dive below 120ft in Travis were there is no light and it seems to take so much extra effort- now the Flower Gardens are a different story.
Andrew

Lately it seems the photocline is more like 70ft.

 

[ianr33]

What is the depth of the River Channel if you swim out from Windy point southwest past Bob Wentz park?
Andrew

Something in excess of 150. Maybe 170???? Will be deeper than that when the lake is full

 

[cyklon_300]

following the explanation of how the rock substrate of the river channel, once completely overburdened by sediment, influences water clarity in the lake.

The channel in the area near WP is essentially a flat, featureless expanse of deep silt which is easily displaced by any movement of water or by contact with an object. Even the smallest disturbance of these fine-grained particles degrades the vis to near zero.

The river channel depth obviously varies with the level of the lake. In Aug 04, at 176' the bottom was still sloping downward at a very slight angle, but this was likely near the center of the channel. Add another 10 feet or so to get a ball park number of max depth...I don't recall what the surface elevation was at the time, but the lake was very full.

For the most part, vis in Travis is controlled by suspended particles from runoff, dissolution/erosion of the submerged limestone strata (observe what severe wave action does to the underwater ledges along the shoreline), and periodic algal blooms. Oh, and don't forget OW classes...<g>

As for diving beyond 120', it's not that big of a deal really...all one needs is technical training and a little bit of extra gear.

 

[Crazyduck]

We get this effect while cave diving certain materials do not fall very easily out of suspension when they are disturbed. That is usually clay, steel (in wrecks) and mud. However, at first I thought it might be an anaerobic algae matt but that wouldn’t work, this would be way too big and thick for that.

Have you considered this to be biological soup leftovers? A combination of algae, lightweight silt, and organic debris? I would expect it would set up very lightly and have similar effects. Has anyone contacted the university biology department and asking if they would like samples? Maybe you could get someone to look at it for you?

Are you telling me that the river channel is like diving at Athens - YUCK (joking!)

I totally agree with you on the technical diving. I find it very challenging and exciting!
We need to meet up sometime and chew the fat, do some diving.

Later dude, Andrew

 

[cyklon_300]

However, at first I thought it might be an anaerobic algae matt but that wouldn’t work, this would be way too big and thick for that.

Have you considered this to be biological soup leftovers? A combination of algae, lightweight silt, and organic debris? I would expect it would set up very lightly and have similar effects. Has anyone contacted the university biology department and asking if they would like samples? Maybe you could get someone to look at it for you?

I totally agree with you on the technical diving. I find it very challenging and exciting!
We need to meet up sometime and chew the fat, do some diving.

an algal mat on the surface of the silt layer between 130-150' that resembles white lace...but it seems to be dissipating recently. The silt layer is not compacted at all, if you extend your hand into it, you cannot really discern if it is liquid or solid. Compositionally, it is probably mostly soil deposits, Travis receives runoff from a large area. But, as you noted, there is a lot of algae and other organic tidbits as well.

Anytime you're going to be in AUS, shoot me a PM, I'm sure we can arrange a tour of the bottom of the lake. We dive it year-round. There's very good vis presently, 30' or so.