Could the Army Corps have done a better job managing floodwaters?

Sunday, May 23, 2010 at 11:45pm

The political narrative of a 1,000-year disaster in the United States typically goes something like this: First, there’s the event itself, which is followed by a few days of somber reflection, then an exuberant burst of civic pride, and finally an extended period of bickering and blame designation.

The last one there may appear to have the markings of the penultimate, but it’s not clear whether anyone is quite sure what happens next. Policy reforms, mass firings, criminal prosecutions? Sometimes, but by the time the wrangling process has played itself out, often nobody’s paying attention anymore. Ask New Orleans. Or, in a year or two, Nashville.

Last week, Rep. Jim Cooper joined with Sen. Lamar Alexander in demanding an investigation into the Army Corps of Engineers and the National Weather Service.

On Monday, Cooper gave a presentation at the Rotary Club of Nashville, suggesting that the post-rain flooding that destroyed neighborhoods in Nashville could have been caused by unnecessary dam releases upstream of the city — specifically dams like Cordell Hull in Carthage, Center Hill Dam in Smithville, Dale Hollow Dam in Celina, and Wolf Creek Dam in Jamestown, Ky.

Cooper also asked why there was so little warning before the flood.

“Here we have minute-by-minute warnings for tornados,” Cooper told The City Paper. “We have nothing for floods.”

On Thursday, Larry Vannozzi, the meteorologist in charge of the National Weather Service’s Nashville office, detailed the timeline. By Wednesday, April 28, he said, the NWS first predicted severe rain for the Middle Tennessee area. It wasn’t until Saturday, May 1, after the rain had already begun, that they began to realize just how severe. According to Vannozzi, the NWS didn’t even release a countywide flood warning throughout Davidson County. He said the unlikeliness of the weather made it nearly impossible to predict just how bad it would get.

“This is greater than a one-in-1,000-year event. There’s a one-in-one-thousand chance of this happening in a given year,” he said, noting that the previous record for a single rain event in Nashville was 6.7 inches. This storm produced more than 13. “We didn’t just barely edge out a record. We destroyed a record. We doubled it. … That certainly makes this more difficult to predict.”

The timing is important, too, because Cooper has also suggested that Corps dams didn’t do enough drainage in the days leading up to the storm, leaving them little room for flood storage.

“What we were able to do on Thursday and Friday was pull a half a foot out of Cordell Hull and Old Hickory,” said Bob Sneed, head of water management for the Army Corps of Engineers in Nashville, countering the claim that nothing was done to draw the pools down.

According to Corps water management records obtained by The City Paper, Wolf Creek Dam was releasing a daily average of between 10,000 and 16,000 cubic feet per second through its turbines in the days before the storm. Cordell Hull steadily increased its flow from around 10,000 CFS on Monday to 18,000 on Friday, also through its turbines. Neither opened its floodgates. In fact, Cordell Hull didn’t open its gates until Saturday, when it averaged 28,000 CFS for the day. By midnight Saturday, it was releasing more than 50,000 CFS.

Cordell, about 12 hours’ waterflow away from Nashville, is able to hold as much as 508 feet of water behind its gates. That is about 5 feet above its normal level, given over for surcharge storage, which basically means very short-term flood storage. But it began those major releases, sending that water straight into Old Hickory Dam and J. Percy Priest Dam, and ultimately, Nashville, at seemingly the worst time possible.

“We wanted to save that surcharge storage,” explained Sneed. That’s because, he said, the storm was headed east, toward Carthage. If surcharge storage had reached its limit when the storm reached it, Cordell may have had to release even more water then.

“It would have been on Monday. On Monday the storm began to move towards the east. We thought it was going to move out very quickly, but then it got into the Carthage area, and it seemed to stall out again. They began to get hammered really hard,” said Hershel Whitworth, a hydraulic engineer with the Corps in Nashville.

According to Sneed, Cordell got up to 508.33 by then, a record for the dam. By Monday morning, it was pumping more than 100,000 CFS from its gates. Old Hickory was averaging 175,000 CFS that day, and was half a foot above its maximum surcharge capacity.

Challenging claims

Cooper acknowledged the overrun at Old Hickory, but he still asserts that many other dams that did releases had unused storage. Cooper insists that Cordell Hull’s true capacity is 513, not 508, pointing to a Corps of Engineers graph showing that height as the very top of the dam, not the storage limit. “I don’t know why that pink line is there, then,” he said. Plus, he said, he believes that Wolf Creek, the largest dam in the system, was underusing its storage capacity by as much as 58 feet, Center Hill by as much as 40 feet.

“I don’t know where he’s getting this from,” said Whitworth. He specifically criticized Cooper’s claim that Wolf Creek and Center Hill were underused. Both of those dams, he said, were rated at a high risk of breach; Wolf Creek in particular is rated extremely high risk. Corps estimates have maintained that a breach there could result in $3 billion in damages and as many as 100 people killed. Center Hill and Wolf Creek have been under construction to fix those issues, but in the meantime, the Corps has lowered their maximum lake elevations to 680 feet (from 720 feet) for Wolf Creek and 630 (from as much as 685) for Center Hill. Records show that both of those limits were surpassed during the storms, Wolf Creek by more than 20 feet. Still, Wolf Creek didn’t reach nearly those levels until Monday, after its turbines had been shut off entirely. It was still doing 13,000-plus CFS releases throughout the weekend.

Water levels must be kept at or below 695 feet (where the entrance ramp is) at Wolf Creek to permit construction. Asked whether those releases were done in order to expedite the process of getting back to construction, Whitworth said, “Yes and no. In order to expedite construction, we try to keep it below 695. We don’t try to keep it below 695 at the expense of downstream flooding. ”

Cooper still wonders why many of these dams are kept so near capacity so often.

“We’ve been battling the Corps for a long time about keeping lake levels down,” said Cooper.

‘Establish a balance’

The answer depends on the dam.

Many, like Wolf Creek, must be kept at or near 680 to keep power generation going. Before construction began on the dam, the Army Corps of Engineers considered going as low as 650 to protect the dam and increase flooding capacity. But an environmental impact study done before construction notes that at 650, “hydropower production would stop completely at Wolf Creek Dam. At elevation 650 [feet], the water level does not reach the intakes for the hydropower turbines. It is likely that water quality and water flow throughout the Cumberland River would be so adversely affected that hydropower would also stop or be severely impacted at the other projects as well.”

For many dams, explained Whitworth, there are other concerns, like federally mandated water levels for recreation.

“We do have a recreation mission. We do have recreation pools. One example is Percy Priest. We are, by law, supposed to maintain Percy Priest at the 489.5 to 490.5 range during the summer,” he said. “In doing that, we do use up some of the flood control capability that the project has.”

Cooper takes issue with that.

“If you ask the Corps, they’ll tell you they’re supposed to keep 9-feet minimum navigation on the river. And that’s great, but who was on the river during this rain?” he said. “Aren’t there emergency rules? Say someone’s drowning, isn’t there an exception? What if they were at 8 feet? Would that have been so terrible? The idea here is to establish a balance. That would be the purpose of a hearing, to find a balance for Nashville.”

15 Comments on this post:

By: EDUNITED on 5/24/10 at 6:42

These intrepid investigators should also subpoena God to ask why God sent so much rain. There's the real culprit!

Ed vanVoorhees

By: mtlycru1 on 5/24/10 at 7:03

yes, well....I'm not sure exactly where Cooper and Alexander get their weather information but it Nashville and surrounding area's were well aware of the coming rains. Cries of "OMG, Mill creek is rising above it's banks".....uhm, yeah - just like any other time in my lifetime in this area (50 years), anytime it rains hard it floods. There wouldn't be a measuring pole at Riverfront if the Cumberland never flooded.

It's truly sad that these political idiots are now turning on any they can blame. Rain happens, floods happen, weather happens......Agreed - this was a catastrophe but people had some warnings and some refused to believe. I myself was surprised at some of the areas that did flood but I'm not going around complaining that it's this group or that groups fault. What Cooper and Alexander should be doing is hitting the streets, helping people deal w/FEMA and Insurance companies that do not advise their clients that flood insurance is inexpensive or making it a law that they must disclose, and be SURE that prospective insured's know that their homeowner's policy does not cover flooding.

As for Mr. vanVorhees....perhaps you'd like to move yourself out to the desert...God had a hand in that too......It hurts that so many lost so much but it would also hurt to not have the water to play in/on (boating/swimming anyone), no beautiful flowers and trees, etc. I pray for those who have been affected and know people personally that were but know that "God" is not punishing or doing this to us.

Politicians, etc.......quit your complaining/blaming and do something usefull.

By: budlight on 5/24/10 at 7:14

Could I do a better job at saving money? Yes Could I clean my house better? Yes Could I take better care of my body/health? Yes

What's the point? They did what they did. They made the best decisions they could at the time.

Can they do a better job? Does a bear poop in the woods? Could the next New Orleans flood be handled better?

Let's just make a plan and get it implemented. Stop the finger pointing.

By: Ex Civil on 5/24/10 at 7:49

What part of civilian control does Cooper and Alexander not understand? The Corps is bound by the mandates congress imposes on the Corps projects, both financial (money for construction) and political. One of those mandates is flood reservations which each dam must maintain based on precipitation projections which at best are a guess. An other issue is who controls the power generation, under Carter's administration power generation for both the Corps and Bureau of Reclamation [mostly in the west] was transfered to the Department of Energy. In a year following this transfer, the flood control reservations at Hover and Glen Canyon were compromised by the Department of Energy the results were:
1) 4 by 8 foot plywood on the Glen Canyon spillway to raise the capacity of Lake Powell (Glen Canyon) to raise the lake level some four feet.
2) Lake Mead lake level reached the spillway at Hover Dam and spillway was used for the first time since the dam was completed.
By the way spillways are for emergency use when the Weather Service guess is a bit too low. The recorded weather history for Tennessee and Nashville is no where near 1,000 years and to make a statement that the storms (more than one) that dropped 14 plus inches on Nashville is a 1,000 year storm event ignores the reality and problem the Corps and the Weather Service have in guessing what will happen when a storm moves in. They do quite well considering the limits of the data at hand.
No I have never worked for either of the two agencies mentioned above.

By: dargent7 on 5/24/10 at 7:55

How could they have done any worse?

By: Kosh III on 5/24/10 at 8:06

One thing that could have been done better:
Someone should have been on-air with a map of the city showing what areas were expected to be flooded and when. Metro and others have maps showing the flood plain.
This would have been better than endless scenes of water, cars floating away, and desperate rescues.

Having a decent idea of whether or not the water would reach your house and when would have been far more helpful.

By: vechester on 5/24/10 at 8:19

Monday morning quarterbacks are always amusing. We just experienced a weather phenomenon that was historic in nature. Modeling this type of occurrence and the volume of water it produced was beyond any of the experts' knowledge of what "could happen."

The easiest thing to do is to look backwards and point fingers at those involved for some perceived "failure." That's what lame politicians do for the public eye. The real leaders will look forward and begin asking the tough questions such as how we can make this area safer when floods happen (and they will), how we can get the information out when they do happen (and we did), and maybe most importantly how will we manage the flood plain now that we have this new data to study.

Politicians always do the easy, visible thing because after all they are politicians. It's what they do. What matters now is how we Nashvillians handle, react and learn from this extraordinary event. No finger pointing, no blame game, just learn and adapt.

By: on 5/24/10 at 8:31

It was all Geo. W. Bush's fault.

By: d4deli on 5/24/10 at 8:49

Here we go, trying to put blame on this thing. It was a flood. It was caused by rain. Anyone near any body of water or trickle of a stream, experienced flooding. Could anyone have predicted this? We all got caught in this unimagineable, unexpected, unbelievable downpour. And now we believe it. We know it can happen to us. Kudos to all of Nashville for rolling up their sleeves and helping folks, strangers and all. WE ARE NASHVILLE!

By: mtlycru1 on 5/24/10 at 9:17

response to Kosh III
Places here flooded that were NOT supposed to could they have used maps, etc. to predict that? I am not near water, no creeks, etc., however due to a low spot on my road, my backyard had a creek develop. My property as well as some I know that WERE flooded are NOT listed on the flood plain map.......

By: budlight on 5/24/10 at 12:17

Kosh, I"m usually in agreement with your "facts" and figures. This time I respectfully have to disagree. People are, by human nature, dis-believing. So the old "if it didn't flood me last time, it won't flood me this time" mentality sets in.

Same as driving through water. Wow! I made it through the last stream bed, or high water. Or I saw a guy in a car just like mine make it.

Hence, "disaster", accidents and destruction. I have an emergency kit equipped with 3 changes of clothes, food, first aid, water, dog/cat essentials and so forth in my "safe" room up on a shelf. When people hear that they ask me "WHY"?

See my point?

have a good one.

By: free thinker on 5/24/10 at 2:38

vechester and d4deli said it right.

By: Captain Nemo on 5/25/10 at 8:57

This was not a 1,000 year flood. A thousand years ago there were no roof tops or asphalts paved roods. Building in a flood prone area is what happens from time to time. Overbuilding in a flood prone area is asking for what took place on May 2, 2010

Cooper and Alexander is what we get for voting for him. They should be looking at the builders and not the Army Corp of Engineers for the flooding. It what happens when we push to far.

By: Captain Nemo on 5/25/10 at 9:16

Cooper and Alexander is what we get for voting for him.

s/h/b voting for them.

By: grouchomarxist on 5/25/10 at 5:40

But [Cordell Hull Dam] began those major releases, sending that water straight into Old Hickory Dam and J. Percy Priest Dam, and ultimately, Nashville, at seemingly the worst time possible.

Will the reporter please explain how water released from Cordell Hull Dam -- which is upstream of Nashville on the Cumberland River -- can find its way upstream of Percy Priest Dam on the Stones River?

Either that water flowed uphill into another watershed, or there's an underground river connecting the Cumberland to the Stones that no one except for Mr. Maldonado knows about.