Feeling the flow.

[Alan Garrett]

I visited a potential cave to dive today near where I live, but I'm having some serious doubts about being able to get in due to the flow. My question is this: The average flow from this spring is 9 million gallons per hour, and it comes out of a vent about 15' high and about 20' wide. How would this flow compare to some of the caves you Florida folks are familiar with? Anything like Madison maybe? I'm trying to get an idea about whether or not the cave can even be entered by "conventional" methods. This spring is actually the headwaters of a fairly sizeable river, so we're talking about a LOT of water coming out of that hole! -Alan

[Limestone Cowboy]

As a comparison, Merritt's Mill Pond (Jackson Blue, et. al.) was gauged at 63 ft^3/second in December 2001. That equals about 1.7 million gallons an hour, the majority of which may or may not come from JB. I have no idea what baseflow contributes in this case, but I started off with the 15' by 20' in mind, decided to look at JB and did the math before I noticed it was for the whole pond.

I think fire hydrant may be a good comparison for your spring. I might look at numbers for Weeki Wachee tonight as a comparison.

Drew

in December 2001.

Keep in mind that the flow during this period was about as low as it has been at JB over the last thirty years.

Putting that in perspective, your spring's flow is about five times what JB's was when it was reasonably swimmable. But it's hard to make comparisons not knowing the size of the tunnels once you get inside the entrance.

[Limestone Cowboy]

From another perspective...

A quick back of the envelope calc says that out of a 15' x 20' opening that volume would be moving at 3/4 mph, assuming piston flow (which it surely isn't)

Maybe 2-3 times that in center of the flow, and 2-3x less along the edges. You might make pretty good progress at that by pull and pull with no restrictions...

I'd be interested if you try it...

Drew

PS Sludge...Ain't it amazing the historical flows recorded at JB? I'd be interested in reports from before the pond was dammed...

I'd be interested in reports from before the pond was dammed...

Go here:

http://www.flmnh.ufl.edu/springs_of_...e_jackson.html

Now if I can just remember what year the pond was dammed.

Russell

http://myfwc.com/fishing/pdf/MerrittsMillPondrich.pdf

It says here the present dam dates from the 1920s.

[Limestone Cowboy]

I'd be interested in reports from before the pond was dammed...

Go here:

http://www.flmnh.ufl.edu/springs_of_...e_jackson.html

Now if I can just remember what year the pond was dammed.

Russell

Got that one on my shelf here in hardcopy

Drew

[Limestone Cowboy]

"In 1868 a dam was built approximately 1.3 miles below Blue Spring. In the 1920’s Merritts Mill Pond was formed when a dam was constructed near the present site at Hwy 90."

I had NO idea it went back that far...

Drew

Sorry for the hijack.

[FW]

I visited a potential cave to dive today near where I live, but I'm having some serious doubts about being able to get in due to the flow. My question is this: The average flow from this spring is 9 million gallons per hour, and it comes out of a vent about 15' high and about 20' wide. How would this flow compare to some of the caves you Florida folks are familiar with? Anything like Madison maybe? I'm trying to get an idea about whether or not the cave can even be entered by "conventional" methods. This spring is actually the headwaters of a fairly sizeable river, so we're talking about a LOT of water coming out of that hole! -Alan

Hi Alan,

When are *we* going

It probably isn't much worse than the entrance at Manatee. Sheck had a plan for high discharge entrances. He suggested dropping a heavy weight in, with climbing rope attached, then "climbing" down the rope with ascenders.

What is the vis like?

Forrest

[Alan Garrett]

Hey Forrest!
I figured you'd respond to this post and I'm glad you did. The vis is pretty bad right now. I'd say it's 10' or less. We've had tons of snow melt draining into the area and the flow seemed very heavy. The spring vent is 70' down and I can still see a little boil on the surface, so I know it's nasty down there. I'd be very interested in learning more about the high-flow entrance techniques you refered to. Sounds like it might be the only way to get in safely. BTW, I think I tried to compare it to "Madison" in my original post, but it was actually "Manatee" that I was thinking of. My bad. If they are anything alike in regards to flow, at least we know it can be done without doing anything too extreme. -Alan