TR Lake Level going forward

[Jerry Rapp]

3 hours ago, Phil Lilley said:

Auxiliary spillway being used would take out all of down town Branson up the hill to the hospital, might take out BS Dam unless they match the flow but then there's the initial push of water they'd have to control.  Then everything below BS - how many towns?

They (Congress) needs to rethink this whole process.

I misspoke... congress doesn't think.

A hydrologist engineer needs to come up with a new plan cause this one isn't working.

is the auxiliary spillway just a cut through the hills?  What is it's elevation?  I assume it is ungated and once the water reaches its' elevation then it free flows?

[dtrs5kprs]

13 minutes ago, Jerry Rapp said:

is the auxiliary spillway just a cut through the hills?  What is it's elevation?  I assume it is ungated and once the water reaches its' elevation then it free flows?

It's a biggie.

[mojorig]

From the USACE - Little Rock Website: "Table Rock Dam’s spillway capacity was evaluated as a result of a dam safety program in the 1990’s. Using improved weather data and more modern technology and safety requirements, engineers determined that the lake would rise ten feet higher during the worst-case flood than previously calculated. An event of this magnitude would overtop the earthen embankment and destroy Table Rock Dam with catastrophic losses in downstream areas including Branson. To prevent the potential loss of life and property damages, congress approved and authorized construction of the Dam Safety Project. After considering several options and gathering considerable public input, an auxiliary spillway was determined to be the best solution. The auxiliary spillway was completed in 2005 at a cost of apx $65,000,000."

Source:https://www.swl.usace.army.mil/Missions/Recreation/Lakes/Table-Rock-Lake/Dam-and-Lake-Information/

[Phil Lilley]

I hear a lot of stories from actual Corps to emergency management people and all of it makes my head spin.  And when it spins, I tend to get confused.

But... I heard from multiple people that in 2015-16 when the lake got the highest, they considered using the auxiliary spillway.  It had something to do with the tailwater release - the elevation of the water and the earthened dam.  Or something else on the Taney side of the dam.  They felt like they couldn't go any higher for some reason.  It had to be something important to be considering "Armageddon".  It was something they had not considered previously - like when they built the dam.

Again, it could be all smoke too.  Nothing official for sure.

I do know during the LAST one - 2017? - the fire department guys came down and told me to evacuate.  They were throwing around the figure 140,000 cfs.  That scared the crap of out us.  But of course it didn't happen.

[Jerry Rapp]

thanks for the info guys.  So it can be regulated with the gates.  If anyone is privy to the Water Control Plan, there should be a section about release schedules for when the lake reaches surcharge level, that is when the lake elevation gets above the top of flood control pool.  I am sure that there are a lot of simulations being run at this time, around the clock.  What a complex system to consider.  In my time in St. Louis, we had several instances of surcharge pool discharges, but never any with multiple lakes in such a vast system.  Every decision made is going to to impact every location the White River  basin and Mississippi system all the way to the Gulf.  Lots of coffee and empty pizza boxes, plus cots and sleeping bags in the Corps offices the next few weeks.

[Phil Lilley]

You're right... very stressful.  That's why I don't criticize the Corps very often.  It's an easy job if you have a crystal ball.

[dtrs5kprs]

23 minutes ago, Phil Lilley said:

I hear a lot of stories from actual Corps to emergency management people and all of it makes my head spin.  And when it spins, I tend to get confused.

But... I heard from multiple people that in 2015-16 when the lake got the highest, they considered using the auxiliary spillway.  It had something to do with the tailwater release - the elevation of the water and the earthened dam.  Or something else on the Taney side of the dam.  They felt like they couldn't go any higher for some reason.  It had to be something important to be considering "Armageddon".  It was something they had not considered previously - like when they built the dam.

Again, it could be all smoke too.  Nothing official for sure.

I do know during the LAST one - 2017? - the fire department guys came down and told me to evacuate.  They were throwing around the figure 140,000 cfs.  That scared the crap of out us.  But of course it didn't happen.

'15-16 was the winter flood? That's the only flood I wasn't there for, until this one.

Mutters something about Vernon...

[MOPanfisher]

It would have to be a situation where literally they thought if they don't open that auxiliary spillway they would lose the dam.  (Think impending failure of Beaver dam), simply to prevent a failure and massive short term flood and subsequent massive loss of property and life, including loss of electrical switch yard..  I know of no other spillway ever designed and placed in a location that would do so much damage, so if it is ever used it will be a major deal.  Considering, planning, writing specs and calculating flows etc. Are a different thing from making the call to actually open it.

[Phil Lilley]

11 minutes ago, dtrs5kprs said:

'15-16 was the winter flood?

Yes

[dtrs5kprs]

8 minutes ago, Phil Lilley said:

Yes

Thanks. That's what I remembered. Odd one out of the bunch.