April 2017 Lake Levels and Flow Rates - over 4ft in 24 hours!

I try not to be critical of Ameren when it comes to their stewardship of the lake or how they treat lake home owners, after all they are an energy company whose only real interest in the Lake of the Ozarks is how much power they can generate and sell while fulfilling their regulatory compliance requirement for having a percentage of that energy produced by "renewable" energy sources.

But when Ameren manages the lake without any apparent consideration for ecology or property? It pisses me off.

Is that a harsh criticism? Does a lake level one foot above full pool really cause issues?  In a word, no. A lake level of 661 is not a "flooding" event at the Lake.  What is an event is rapid change. Take a look at the level and flow chart for April.  See anything striking? It's not the 661 lake level itself, but how fast it got there that is the problem.

The forecast for potential flooding rains was anticipated early in the last week of April and Ameren, as to be expected, began ramping up turbine flow on Wednesday April 26th, with full flow by Friday the 28th. But as the rains fell Ameren surely watched as lake levels began to rise at an alarming rate. This rate of change continued for nearly a day with full turbine flow (35Kcfs) having little impact on lake levels. At it's most dramatic, the lake rose one foot in just four hours on Saturday.

Ameren saw this rapid rise but did nothing until Sunday, April 30th at 6:00am. With the lake at 660.51 the flood gates were finally opened. Let's be clear here. It wasn't until the lake's level punched through 660ft (full pool) that flood gates were opened Sunday morning. This means that in just under 24 hours the Lake of the Ozarks was allowed to rise over 4 feet!

Note: My statement above, that flood gates were not opened until the lake reached 660.51 feet, is (indirectly) disputed by Warren Witt, the Director of Hydro Operations at Bagnell Dam who was quoted as saying they were opened when the lake reached 659.5 feet in a later interview with  Lake Expo. But I'm going off Ameren's own data so you be the judge (zoom in on the above chart). From the above chart the flow rate was still about 35,000cfs when the lake was at 659.5. But Witt should know of course when the gates were opened, and it is certainly reasonable that there is a delay from the time flood gates open until the change in flow rates registers with Ameren's own sensors. Flow rates measured independently by USGS seem to back up his statement that the gates were opened at 6am, so I'll have to give the benefit of the doubt here.

I'd have to check my own records, but I'm pretty sure the floods of 2015, both of them, didn't rise so quickly.  This rate of change is highly disruptive to the ecosystem and damaging to the very shoreline that Ameren makes us lake home owners all bend over backwards to protect.

I would not argue that there was anything that could have been done to prevent reaching the 661ft level given the pressures from Truman Lake and the Osage River, but I believe an earlier opening of the flood gates would have made the rate of change a little more bearable.  Management Grade? D

2016 Bagnell Dam Operations Summary

Multi-Year Level and Flow Averages

Here are the graphs for average lake levels, Osage River levels, and flow rates since 2010. As we can see, 2015 was an exceptional year for lake levels due to flooding.  Keep in mind, these are averages for the entire year as numbers for the summer months would be almost identical from year to year since Ameren does a pretty good job of keeping the lake at full pool (659-660ft) from May 31 through September 1st.

Next, for the Osage River as measured about a mile below the dam, again per annum.

Finally, the average flow rate per annum. Averaging about 10,500cfs a day is considered sustainable.

2015 Update - Multi-Year Levels and Discharge Analysis

2015 was a record year for the lake of the Ozarks.  Two major flooding events and a no-wake executive order from the Governor were just some of the highlights.  Here is the full analysis of operations at the lake of the Ozarks, now with 2015 data included.

Flood Watch 2015 - River Gauge at St.Thomas

Here is the graph from the USGS Hydrologic unit at the Hwy B bridge near St.Thomas Missouri. This is the last measuring unit before the Osage River meets the Missouri River, about 15 miles from the confluence.  Flood level is the 23' red horizontal line, and likely to be reached within a few hours.

June 2015 Lake Levels,Discharge, and Osage River Levels

June is looking like it will go into the climate books as the wettest on record and the effects on the Lake of the Ozarks can be seen in the level charts.  Despite downriver flooding pressure to minimize the release of water from Bagnell Dam, Ameren allowed full turbine flow (green line) nearly 24/7 but avoided resorting to opening flood gates (video).

A reduction in turbine flow starting on the 16th was followed by an abrupt rise in lake levels that briefly went over the 660' mark in the early hours of the 18th.  Renewed maximum turbine flow quickly reduced lake levels but overshot the average by June 20th, again prompting the reduction of turbine flow to re-raise. By month's end, levels stabilized to the five year average while turbine flow still remains high.  With July starting off as another wet month, it is likely Ameren will have to remain nimble with their hands on the valve.

Figure 1

The effect of the relentless turbine flow (whether generating power or not) on the Osage River is seen in the tailwater chart below, expectantly matching turbine flow in figure 1.  While the river remained very high, changes in levels were limited to just a few feet.

Figure 2

May 2015 Lake Levels,Discharge, and Osage River Levels

Despite all of the rain, May finished just below full pool, but a foot above the five year average for this time of year, as indicated by the dotted orange line.  As we can see by the green discharge rates peaking at licensed maximum of 35,000cfs, Ameren has been generating a lot of electricity. Discharge rates nearly maximum around the clock have a significant impact on the Osage River levels below Bagnell Dam, as can be seen by the chart below for the same period of time.

Notice that these swings in level starting on the 12th are almost 10 feet and remain high into June.

1902 - Confluence of the Osage and Niangua River

This is an amazing pre-Bagnell Dam picture of the joining of two major rivers, the Osage and Niangua, from 1902.  These rivers now feed the Lake of the Ozarks and in 30 years time from this photo, this farm and land will be underwater.

The State Historical Society of Missouri, Photograph Collection

2014 Annual Lake Ozark Levels and Discharge Summary

Here it is, the complete daily summary chart for 2014.  It's done in a style that captures the daily highs and lows, starting level and ending level, along with the total discharge of the day. There's quite a bit of data in this one chart, and you'll need to download the full size for details.  

In general, 2014 lake levels conformed poorly to established guidelines.  The annual drawdown to bring the lake to its lowest levels came late in January, after a brief rise in levels, and was executed in very short order causing much damage along the Osage River (see Osage Tsunami). Summer levels were maintained at a comfortable 659'-660' level (full pool), but an early drop to 658' in late August was held beyond Labor Day. Lake levels in October actually reached full pool again but gradually returned to the expected level of 658' midway through November.  In late November levels once again deviated from guidelines to reach full pool and the lake finished out the year at its highest levels.

Here are some of the key data points for the year.

Most water discharged in a single period (hr): 38,778 cfs on Feb 4th at 8pm.  This is the only time Ameren reached the maximum discharge allowed by license.

Highest Lake Level:  660.20 on December 31st at 2am, a very unusual time of year for the highest level.

Lowest Lake Level: 653.74 on February 7th at 9am.  Typical.

Average Lake Level for the year:  657.82'

Osage River:  Range for the year was 551'-567' with the average being about 554'.

The head of the dam is the difference between the lake level (headwater) and the river (tailwater) and determines the power generating potential of Bagnell Dam.  The higher the head, the more power that can be generated.

Highest Head:  108.40 ft

Lowest Head:     87.26 ft

Head Average:  103.88 ft

Full size image (3MB jpg) here

1886 Osage River - Not Worthy of Improvement

The idea of building dams on the Osage River goes back as far as 1886.  From the first session of the 50th U.S. Congress,  an excerpt from an evaluation of the potential commercial value of developing a lock and dam system on the Osage river by the U.S. Army's Office of Chief Engineers.



Full article from Google archive.

Osage River Levels Fluctuate Wildly

Update:  This post has generated a lot of interest.  A more in depth analysis of the event is here.

The cold temperatures are creating energy demands and Ameren UE is making hay while the sun shines generating power at Bagnell Dam.  While deepening the annual draw down on the lake, river levels below the dam have peaked and crested over ten feet at least five times since midnight February 4th, 2014.  I've kayaked this river from Bagnell Dam, ten feet is a dramatic difference on riverside property in some areas.  Changes this deep, this rapidly are difficult to imagine.

Ameren Data

Discharge rates provided by the US Geological Service confirms power generation.