So, here is the "math" on the effect on Lake Athens, so far. Of course, before I show it, remember that the same run-off from saturated soils in the two lakes' watersheds and actual rain hitting AF&G is hitting Lake Athens, too. In other words, not all of the rise in Lake Athens is attributed to run-off from AF&G. Not even close.

But, at normal conservation pool, Lake Athens holds 29,435 acre-feet of water. So, it averages 16.36 feet in depth (29,435 / 1799 surface acres). Today shows 32,368 acre-feet of water, so it is now 17.99 feet average depth.

This comports with the data on the lake; that, and the photo of the boat ramp suggest this same rise.

But, as water fills a reservoir, its area increases; it isn't like a glass with vertical sides. So, the rise covers a larger lake now . . . as it moves up into the properties surrounding the lake.

Athens Municipal Water Authority, I think that is what it is called, owns all land around the lake's perimeter up to at least 448', I guess more around the dam.

Gary R. : If you know the surface acreage of AF&G, there are some interesting calculations to be made.

*** My guess is that the boat ramps aren't closed because Lake Athens is up less than 2 feet, it is closed just in case the "dam" gives away and all of that water comes flooding out all at once.

This should not result in a long term closure; the closure will be in effect until the risk is eliminated. How to do that? Well, if the small lake drains off to a certain point, it poses no immediate risk. But, heavy rain events could cause them to toggle the boat ramps open and closed until things sort themselves out.

Road crews are up next and it sounds like they need to beef up the road that is acting as a dam. What likely was just a traditional road is going to need to be buttressed with a whole lot of very heavy concrete, else this saga will play out again at some point.

Brad

Okay, I found a reference to AF&G as a "135 acre" lake and Gary likely has a good idea of its average depth and if I use 10 feet, that would be 1350 acre-feet of water in the reservoir compared to 29,435 for Lake Athens which is normally 1799 acres and a normal average depth of 16+ feet. So, if ALL of the water came gushing out of AF&G, it would only increase Lake Athens' water volume by about 4.5%.

A big rain with watershed run-off would do that much to Lake Athens, so, again, the ramp closure has little to do with the recent rise on Lake Athens, more to do with a possible sudden surge or wall of water if the whole dam crumbled. If the ramp were farther away from AF&G, I don't think it would be much of an issue at all for Lake Athens.

Even then, and Gary and others would know, not ALL the water would drain out of AF&G as I suspect that there is some depth of water below the bottom of the dam (highway).

Brad

I wonder if the engineering played out with the intent to use the dam as a road or the road as a dam. The order is critical when it comes to dam safety with the latter obviously being the most unsafe option. Hope this all plays out well...

A couple Frac water transfer pumps pushing 130 barrels per min from AF&G to Athens would sure help release some pressure on that dam/road.

AgSellers04,

Good question! It looks to me like they just used the road, likely altered and beefed up a bit, as the dam . . . and not vice versa.

That makes sense: the engineers make calculations, not hard to do, but then it comes time to fund such things . . . and money becomes an issue. Most engineering calculations have very large fudge factors built in, sizing a beam comes to mind, so the politicians, taxpayers too, likely talk the engineers down a bit to some acceptable lower standard.

Then, Mother Nature gets out her lesson plans and everyone gets schooled.

Brad

Brad,
Cool math you are calculating. But you need to use 190 acres. The avg deep is indeed about 10-feet. And while there is 22' water by 317 and the dam, it's an area about the size of a basketball court.

The problem with fraq pumps is that there's nowhere to pump the water. Tons of houses and farms directly across 317. Thus, the voluntary evacuation notice. The state engineers were there all day. Let's just hope there isn't another turd floater.

Brad,

I understand that concept all too well. That's why we (they I mean) over-engineer things most times. I'm just the environmental guy that tells them they are wrong and gets ignored half the time. "But.. but...but it works in the models and in my schematics" That's a popular line.

The dam has been there since 1921 when a bunch of rich dudes from Athens decided to build it as a place to play. I'm guessing that was long before state highway 317 was established.

I was speaking with an AF&G property owner today and the same question came up "which came first, the dam or the road?" he said the lake was built in the 1920s. We figured the state built the road on the dam. And that brings up a whole new set of questions. I just hope the rain holds off long enough to get the road/dam stabilized.

So you can't fish Lake Athens right now?

Well that answers it then. Re-engineering something away from it's original intent is always bad. "We'll reinforce it" That's the solution, works sometimes. I imagine people have always driven over it just not at modern day volumes.

Hopefully they can get it right this time around.

A quiet night on Lake Athens with the water dropping a smidgen to 441.98' as of 5:30 AM this morning.

One more math stat along with my coffee this AM I'll pass along:

The Lake Athens dam controls the drainage for 21.6 square miles, so that would be 13,824 acres, actually a small amount of watershed as would be expected for a relatively small lake. If every inch of water that fell in that area drained off, say the ground was totally saturated, one inch of rain would raise the lake level by 7.68 inches.

Anyway, let's hope the disaster for AF&G has been avoided.

Brad

Any updates Gary? Have they done anything in attempts to patch it as the water drops?
I'm hearing the rain is starting down there already.

According to this website http://hendersoncountytexasnow.com/tceq-expert-on-dams-consulting-on-fish-and-game-lake-breach/
"** UPDATE: Tuesday, 3 p.m. �. County officials have verified that engineers are planning to conduct a controlled breach of the dam Wednesday morning."

I wonder how deep they will "cut" the dam and how much water they'll want to remove. I also wonder how much more water Lake Athens can take.

Lake Athens does not have a gate to "open",,,, just the drain hole at the dam...... right ?
Can the water pump station take more water out than is usual ?
I was there today at lunch and the water level is very high, almost into the ramp parking lot, covering all the boat docks at the ramp. Many home owners have taken their "big" boats out of the boat stalls to keep them from going thru the roof as the water rises. No rain here in Athens today, just a couple of slight sprinkles, but I see the water coming up more before it goes down, just MHO.
The North end towards the AF&G looks real muddy, but the main lake looks clear.
Lots of debris, grass and weeds in places they should not be.
Athens Water folks were there at noon taking water samples to be tested.
Athens Water District has a "boil your water first" directive on right now until further notice.
Don't know what got into the water but something has.
Looks like I'll be going South to fish this weekend.
Maybe Toledo Bend,