WARSAW, Mo. — Built for flood control downstream, Truman Lake’s flood storage capacity is nearly maxed out: heavy and persistent spring rains have taken their toll. Truman Dam, which impounds the lake, stopped discharging water last week, to prevent flooding at Lake of the Ozarks and downstream on the Missouri River, but the Army Corps of Engineers says the dam has begun releasing water this week. The Corps has reported the floodgates began to be opened on Tuesday.

According to a press release from the Corps, "Harry S. Truman Lake is 82 percent occupied leaving minimal space to store additional flood waters." The Corps added, "May 2019 has been the second highest monthly inflow to Harry S. Truman Lake in project history." Ameren reported on Monday that Truman Lake was at 736 feet of elevation: 30 feet higher than its "normal" level. A pedestrian, David Shayani, took the following video of Truman Lake's water level nearing the top of the spillway gates on May 27, 2019:

In a report issued on Monday, May 27, Ameren—the utilities company that owns and operates Bagnell Dam, which impounds Lake of the Ozarks, into which Truman Lake feeds—noted it would increase Bagnell Dam's discharge to approximately 40,000 second-foot-days (sfd) by Wednesday, which means the generators would be running at full capacity without the use of floodgates. But Ameren said by Thursday or Friday, Bagnell Dam will likely open the floodgates.

“Moderate flooding on the Osage River is likely later this week,” an Ameren employee said in the report.

The Corps called the actions at Truman Dam “precautionary and necessary to ensure public safety,” noting, “human life & safety are the priority in reservoir operations.”

“As pools at Corps lakes rise, additional personnel including park rangers, maintenance personnel, and engineers from the Kansas City District Office routinely inspect the dam, the spillway, the powerhouse, and other important structures,” the Corps said, emphasizing, “All dams are structurally sound and are [performing] as designed.

Earlier this year, LakeExpo.com broke a story that Truman had been rated by the Army Corps of Engineers as Potentially Unsafe or Very High Risk. The dam received a “2” on the Dam Safety Action Class (DSAC) scale; a 2 rating is described by the Corps this way: “DSAC Class II Urgent (Unsafe or Potentially Unsafe) – Characteristic: Failure Initiation Foreseen or Very High Risk. Dams where failure could begin during normal operations or be initiated as the consequence of an event. The likelihood of failure from one of these occurrences, prior to remediation, is too high to assure public safety; or the combination of life or economic consequences with probability of failure is very high.”

Truman Dam Safety Program Manager Pendo Duku explained in an interview that the rating did not mean the dam was structurally unsound, but that in the potential flood event that would cause the dam to be breached, the downstream consequences of such a breach would be major. The rating, he explained, was about the potential consequences of a catastrophic flood, rather than about the structural soundness of the dam.

In a dam safety meeting on March 13, Scott Mensing, Dam Safety Expert for the Corps, said, “We can reduce the amount of flooding, but we can’t stop it… There’s always a chance of a flood that will come that the Corps can’t handle. And it’s that event, even though it is extreme, it is rare, it is highly unlikely… it could happen. I can’t say it can’t happen.”

Truman Dam has inarguably saved downstream communities from greater flood damage since its completion in 1979. According to one Corps document, the dam prevents an average of $103.2 million per year in flood damage. During the 1993 flood, the dam prevented flooding damages of $230 million, the Corps has estimated.

Mensing also pointed out that Truman Lake—the largest lake in Missouri—was capable of absorbing the full impact of a breach from a dam further upstream, without there being any further downstream consequences.

“The amount of water that Truman can hold is tremendous,” he said. “Its primary purpose is flood control.”

As for the dam’s safety, Mensing explained the Corps’ inspection schedule:

“We do daily inspections… the park rangers and the operators that you know, they’re out every day, looking at the dam.”

Once a year, the district office in Kansas City comes out for a two-day walk-through inspection.

Every five years, there is a three-to-four-day inspection. The last was in 2017, where 30 people inspected “darn near every single inch” of the embankment, powerhouse, and the multiple dikes.

Every 10 years, the Corps performs an in-depth risk assessment. It was that risk assessment that led the Corps to raise Truman Dam’s priority level from a 4 to a 2, he said.

“Every one we do, we’re learning from it,” Mensing said of the assessments. “Over the last 10 years, the Corps has learned a lot about what’s a tolerable risk, how to better analyze hydrology, how to better understand dam performance… we’re getting better ideas of how people react to an emergency.”


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