Why is the viz crappy at Manatee?

[jj1987]

Just curious, Marchand and I dove there today and had 15ft viz at best, even past the milk/sewer tunnels. I'm used to the first few thousand ft being fairly bad, but then clearing, so we rode just over half an hour upstream of Friedmans, and there was no sign of clear water or even improvement.

I had assumed with the lack of rain recently that we would have decent viz, any reason why we didn't? The flow seems completely unaffected, not up nor down.
Pics-

[cavediver256]

Poor technique?????

[jj1987]

Poor technique?????

Couldn't have been...we were the only team in there

[RN]

I think that's what he was saying...

[cavediver256]

Just a question, but are they still mining in the area of Manatee or was it stopped????

[Cindy]

The mining was stopped a long time ago. The Longs headed that effort up. I know manatee gets some tidal influence. That shouldn't make it milky unless the flow is really low and there is some algae bloom. Maybe a small collapse in the milk tunnel. It's interesting. Someone needs to go in at Freidman's and let us all know.

[apitkin]

Although the visibility is often much better upstream of the Milk Tunnel, it still varies quite a bit, and I don't think anyone really knows why. If anybody does, it is Mark Long. One possibility is that there are some paleosinks a long way upstream (e.g. Sheck's Hill in the Snow Tunnel) that may transmit surface rainwater into the cave after heavy rain.

Andy

[KarsticGator]

One possibility is that there are some paleosinks a long way upstream (e.g. Sheck's Hill in the Snow Tunnel) that may transmit surface rainwater into the cave after heavy rain.Andy

I agree. That area is very karstic, so i wouldnt doubt that there are some surface sinks that feed the watershed. These surface sinks may have considerable algae blooms, and particulate is brought down into the cave from these seemingly stagnant karst windows.

[jj1987]

Posted a question on facebook and got this answer...So far this sounds reasonable....

Hey James, Manatee is a bit of an anomaly as it is actually worse when with less rain which lowers the hydraulic head (basin water level) and allows the milk and sewer tunnels to flow more prominently. When the water is very high those tunnels are more or less shut down and the water is beautiful. Not easy to time but a real pleasure when done well.

Now I have something to look forward to with the flooding

[apitkin]

Posted a question on facebook and got this answer...So far this sounds reasonable....

Hey James, Manatee is a bit of an anomaly as it is actually worse when with less rain which lowers the hydraulic head (basin water level) and allows the milk and sewer tunnels to flow more prominently. When the water is very high those tunnels are more or less shut down and the water is beautiful. Not easy to time but a real pleasure when done well.

Now I have something to look forward to with the flooding

Well, that is partially true, but the hydraulic head depends on the water level in the Suwannee, which depends in turn on the amount of previous rain in its watershed in Georgia and the panhandle, and also the tides in the Gulf of Mexico. When the river level is high, it suppresses flow from the Milk and Sewer tunnels and visibility can get very good (even in the Sewer tunnel). That's why Manatee is such a great option when all the other caves are flooded, as the flow is down too. If you can time your dive at high tide then you'll usually see better conditions too.

Local rainfall probably does not have a beneficial effect on visibility at Manatee.

Andy'