Once the Missouri River drops below 90% of crest at Herman, they will again begin discharging from Truman.

Spring melt and rain always raise the chance of flooding. Predicting the impact of flooding and when that may or may not occur on Lake of the Ozarks is the challenge for the the operators at Truman and Bagnell Dams. 

Logistically, flooding above and below Bagnell Dam will impact levels on the Lake of the Ozarks. 

Warren Witt, director of hydroelectric operations for Bagnell Dam said the biggest impact right now is actually from flooding on the Missouri River, downstream of Bagnell Dam. 

The Corps operating rules for both Truman Dam and for Bagnell Dam state that when flooding on the Missouri River at Herman, MO reaches 260,000 CFS or higher, they curtail discharges from Truman and ask operators at Bagnell Dam  to curtail discharges until the river crests and drops to 90% of crest flow.

“That is where we have been since Sunday,” he said. “This is so that the Osage River flows do not add any more to the flooding on the Missouri River.

According to Witt, curtailing discharges from Truman Dam means that their lake continues to rise higher in their flood pool.  Once the Missouri River drops below 90% of crest at Herman, they will again begin discharging from Truman.  

“The amount of discharge will depend on how high their lake is at the time.  If it is between 706' and 717' when they start discharging, they will discharge around 34,000 CFS (cubic feet per second) and we can keep up with that with our generating units and the Lake of the Ozarks level won't go up much,” he said. “If, however, Truman gets much over 717', they may have to discharge at 54,000 CFS, which we cannot keep up with generating units.The Lake of the Ozarks level would then go up and may reach flood level of 660' and Ameren would have to open flood gates.

Witt said based on current information the projection is for the Missouri River at Herman to get below 90% crest on Saturday.  By that time, Truman will be right around 717'.  They do not plan to have to go above 34,000 CFS at this time.

“If we get more rain or the Missouri River doesn't crest as soon, that could get us into flood conditions,” he said.

Fluctuations in Lake and river levels occur for several reasons. 

Ameren Missouri generally lowers the water level at the Lake during winter months to about 654 feet above sea level—or six feet below the full reservoir level of 660 feet—to reduce the possibility of flooding during spring rains.The Osage River level also fluctuates when Ameren Missouri’s Bagnell Dam releases water during the draw-down and to meet the demand for electricity.