Historically, lake-area residents begin to get antsy about this time of year because lake levels are low, and they can't get their boats off their lifts and they wonder aloud when the lake levels will be coming back up.
Not this year.
As of mid-day Tuesday, the Bagnell Dam Plant had recorded 6.01 inches of rain in April, which surprisingly is on par with a year ago. Heavy rains upstream on the Lake of the Ozarks and on Harry S. Truman lake drainage basin have combined to push lake levels about two feet above what is consider "normal" for this time of year.
Ameren Missouri is licensed by the Federal Energy Regulatory Commission (FERC). One of the license articles is a guide curve, which is a set of target lake levels throughout the year. The guide curve for mid-April is 656.16 feet above sea level, and the elevation was actually 658.23 as of 8 a.m. Wednesday.
Alan Sullivan, Ameren consulting engineer at the Bagnell Plant, said the objective is to raise the lake level to near full pool by Memorial Day weekend.
"We're not concerned about getting the lake up to recreational levels even if it doesn't rain for awhile because there's a lot of water stored at Truman Lake now," he said. "Even if we thought it was going to be dry, we could store the water out of Truman to keep the lake levels where they need to be for Memorial Day."
He said that if the rains subside, plant engineers will allow the levels to fall a little as Truman reduces its discharge so the Lake of the Ozarks meets the guide curve. Truman was at 715 feet above sea level, giving that lake about nine feet of storage.
"We as hydroelectric engineers get a little uncomfortable with the lake being as high as it is," Sullivan said, "because if we get four inches of rain, that would be a significant amount and we would lose storage capacity to allow for potential inflows. This loss of storage in the Lake of the Ozarks, especially in the early spring, really increases the potential for flooding, both on the lake and in the Osage River below."
Last fall, after a long, hot, dry summer, Bagnell Dam was running a minimal daily discharge of about 900 cubic feet per second. A typical day of generation might be 12,000 cubic feet per second, Sullivan explained. As of Tuesday, the discharge was 34,500 cf per second, 24 hours a day.
"For the time being, we will be able to avoid opening the flood gates," he said.
Another few inches of rain could change that. The Osage River will be bank-full for the next week or two as Truman and Bagnell Plant engineers manipulate the flows to maintain adequate reserves and keep water levels at guide-curve levels.
Page 2 of 2 - "Truman is beneficial upstream neighbor to us," Sullivan said. "We have good communications with the Water Control people who manage lake levels for the Truman reservoir. We talk to them or email them several times a day. We also continually watch the National Weather Service weather forecasts, including the QPF (Quantitive Precip Forecast) so we can make the best decisions possible for lake management."
Rainfall in April 2013 is virtually the same as April 2012.
But a year ago, the rain stopped. May rainfall was .88 of an inch, June was 1.48 and July was 1.46. That could happen again this year, and Bagnell Plant officials want to maintain adequate storage in this lake and Truman to offset potential dry months.
The FERC lake level guide curve bottoms out in mid-February at about 654 and remains flat until April. By late May, the lake level rises to 659, one foot shy of full pool.
With warmer and dryer weather predicted for the weekend, boaters should have more than adequate lake levels to prepare their boats for the season.