Unmanned Drones On The Lake

 I'm going to have to give Lake Expo a lot of credit for making this blog a little more obsolete. They're starting to do some decent journalism and looking into things before most of us are really aware. Good work. So I hope I give all due credit for the inspiration of this post.

To that point there is the story today about Unmanned Surface Vehicles being spotted around The Lake.

USV - Lake Expo by Tegan Pasley

In short, a company named Simple Unmanned LLC is doing a bathymetric survey of The Lake using unmanned drones. Note: Sorry, Tegan, but your suggestion that drones would be a good idea for Door Dash is not really practical...as of yet. Does anyone remember Domino's pizza delivery on The Lake?

Anyway, Tegan reports that Water Patrol and Ameren are aware and "monitoring" the drone activity, but I want to talk about Ameren on this matter. They need to do more than just monitor, they need to act on the data. Somewhat for themselves, but mostly for property owners like me.

Sedimentation map of a boat ramp launch. Source Simple Unmanned LLC

The Lake is filling in. Despite the decades of development and subsequent improvements such as concrete swales and other erosion prevention measures, sedimentation of The Lake continues. I live at the back of a cove and can honestly say I've lost 2 feet of depth since the 70s. We have dredged (permitted of course, and only within the footprint of the slip!) prior to the ban on dredging in 2007, but overall it's a losing battle anyway. Eventually, my property will no longer be waterfront and there doesn't seem to be a lot I can do about it. It sucks for my property, but what does it mean for Ameren?

Does Ameren care if The Lake fills in? Of course, but not in anyone's lifetime. Sedimentation near the shoreline can go on for centuries without affecting the performance of the dam as a power generator. The turbines only care about "head height", and with over 600 billion gallons of water, volume is never really a problem. Unless.

Heavy sedimentation of The Lake means overall volume is reduced. Volume management is the basis for Ameren's tight-assed control of the shoreline. The volume of water stored behind a dam represents it's ability to maintain energy production in periods of changing conditions. While The Lake is fed by many sources, constituting nearly 10,000 cubic feet per second flow at all times, prolonged and severe drought would have an impact. Meaning in times of extended drought, the reservoir could drain faster than it is replenished. Maintaining The Lake's ability to retain as much water as possible mediates such issues. 

Think of it this way. If the contour of the Osage River valley had been deeper and steeper, before it was flooded by Bagnell, then the main channel of The Lake would be less wide than it is, and there would be far few fewer coves, but the dam itself would still be able to generate as much power. The only difference is that it would be far more susceptible to rainfall, closer to a "run of the river" style waterwheel power generation. See my lengthy article on how Bagnell Dam works. In other terms, Tam Sauk Dam, a completely different type of dam, used more as a battery than a generator, can produce more power than Bagnell using a fraction of the amount of water. It just can't do it for very long.

As a power generating system, Ameren isn't too worried about sedimentation, but somebody is or Simple Unmanned would not have been contracted to perform this very expensive work. I wanted to do something similar with side-scan sonar systems, but didn't really see the value in a full detailed bathymetric data set for The Lake. It would be fascinating though and I do hope the results of this survey, and the data will be shared with the public (or me!).

The End of Tunnel Dam

I've been a fan of the Tunnel Dam ever since I discovered it while looking for places to kayak in the lake area many years ago. My "discovery" was a bit embarrassing actually. I spent a lot of time at Ha Ha Tonka even before it was a state park and I had never heard of Tunnel Dam until the early 2000s.

The big news is that Show Me Electric Power Cooperative has elected to not renew the license to operate the hydro-electric facility, and it appears power generation will cease this year. Lake Expo has a very good article on the situation and I recommend reading it for more information on the local impact, including this nice history link from the Show Me Electric Power Cooperative. 

Best described by Show-Me Electric, "Attention was especially attracted to one potential site where a natural cave or tunnel pierced the base of a narrow ridge, bypassing a meander of the river, thus affording the opportunity of obtaining an artificial fall of water and creating a forty-foot head for a hydraulic turbine." In the case of Tunnel Dam, this 300 ft. wide ridge cuts through six miles of "meandering" river.

Satellite view of Tunnel Dam next to its Generator House

By creating Tunnel Dam, Lake Niangua was also created, which is fed by the Niangua River, a river as beautiful as any in Missouri, only less protected, and surrounded mostly by private farm land. Lake Niangua is very tranquil and beautiful as well, but is too small to be anything more than a nice place to fish.

Tunnel Dam is five miles southwest of Ha Ha Tonka (as the crow flies). The image below tries to show location and scale of everything.

The Niangua River is a major source of water for the Lake of the Ozarks, and with the fate of the dam structure itself, and the lake it forms, in question we need to examine the potential impact to the Lake of the Ozarks.

If the dam is removed in a controlled manner, the impact on the Lake of the Ozarks would be negligible, but if the dam remains, but not properly maintained, it could ultimately fail. A catastrophic failure, a total and rapid collapse, would cause a great deal of damage downstream, all the way into the Lake of the Ozarks.

But lets assume the dam is decommissioned in a controlled manner, whereby it is removed and any sudden deluge of water avoided. What this means for the Niangua River is an uninterrupted flow of water from Hwy 44, past Bennett Springs, all the way into Lake of the Ozarks. We already have a sanctioned 12 mile float below Tunnel Dam, called the Big Niangua River Trail that ends at the Lake of the Ozarks, but with the Tunnel Dam removed, this could turn into many dozens of miles. The potential for floats and water traffic goes beyond just kayaks and canoes. I have paddled up river from Lake Niangua and can say it is a very serviceable river for small power boats. My jet boat runs the Current River all the time in water barely knee deep, even less. Who knows how far up the Niangua River one could reach from the Lake of the Ozarks without the Tunnel Dam structure in the way. 

NOTE: Full disclosure, Whistler Bridge, just below Tunnel Dam is an impassable low water concrete bridge so any boat traffic would have to remain above or below it, but that barrier too could be removed. While I am a bit sad Tunnel Dam's life is ending, I think the idea of the Niangua River being a serviceable recreational artery all the way into the Lake of the Ozarks intriguing.

2019 Flooding

I'll be posting my monthly graph of lake levels and flow rates for the Lake of the Ozarks tomorrow, or Monday, but as you will see despite the high water levels in other lakes and rivers, the Lake of the Ozarks is operating at normal levels. How can this be you may ask?

What's so special about the Lake that it is spared the ravages of flooding while the Osage and Missouri Rivers flood and Truman Lake is busting at the seams?

With the 30 day outlook calling for a wetter than normal June, things may not improve much.

The answer as to why the Lake of the Ozarks seems out of step with other bodies of water in the area is not a simple one, but it is important. It has everything to do with the very different purposes for which the two dams, Truman and Bagnell were built, who controls them, and the river basins they serve. I've spent a little time explaining it here if you're interested.

2018 Shootout Meet and Greet Parade of Boats

Best. Ever.

A couple of things changed this year with the Shootout parade of boats on the Dam for 2018. Firstly, the boats were lined up on the sides of the strip allowing the crowds a center aisle to move about. This really made things much easier for everyone to get around and see all of the boats. I'm sure some of the bar owners felt it obstructed line of site of their establishment but from what I could tell it had little impact on the amount of business they were getting. Casablanca, High Noon, Lucky's and all the others were very busy last night.

The center lane was used for pedestrian traffic with boats on each side.

Which brings me to the second welcome change for the parade, open containers. No glass of course, but for the first time since I've been going to the event, you could walk around with a beer in a cup. I know that sounds like an unimportant thing but relaxing open container laws for an event such as this has a rather dramatic effect in general. First of all, people get out and see the boats, not being confined to have their drink in an establishment. Secondly, being able to take your drink away, leaves room for others to come purchase one for themselves, providing for a nice steady flow for business. Win, win. The police were out in full force, polite and professional, but certainly there to make sure things didn't get out of hand. I drove through the strip on the way to work this morning and saw a surprisingly small amount of litter, so everyone did their part to keep things clean. Thanks to the City of Lake Ozark for the welcome changes that made for a great night for all.

More pics!

Things started off a bit slow

On the deck of the recently opened High Noon

Now we got a crowd!

A lot of boat for two people!

People from one end to the other on the strip

Console boats are getting more popular

This boat was the Belle of the ball if you ask me

Power to spare

awesome lighting

Winding down for the night.

Lake TV has a nice two and half minute long video with some cool drone footage mixed in.

Making a Dam Heavier

The Summer of 2017 is rapidly coming to a close but work continues on Bagnell Dam. I'm sure everyone has noticed the cranes, cement trucks, and workmen busily making the structural improvements outlined by Ameren in March. This $52 million dollar project will enhance the structural integrity of the dam, something not done since the 1980s.  Improvements to energy production efficiencies has been fairly steady over the years, but actual structural work has not been performed in some time. One notable exception. Ameren renewed their license to operate Bagnell Dam in 2007 after years of stakeholder input and millions of dollars spent to comply with many regulations. It was about this time I noticed new concrete at the Eastern(? it always feel more like Northern to me) entrance. This relatively small addition is sandwiched between the Eastern abutment and the cliffside near it and presumably added to stabilize the abutment itself(East and West abutments are the "solid" parts of the dam that have no spillways). Update - I've just noticed some new forms on this structure now, an indication more concrete will be added to it as well.

The work being done now is the addition of new concrete and 68 more "anchors". These new anchors are not meant to replace the 277 nine inch steel rods that were installed in the 1980s (a 2009 article from Connectmidmissouri.com quotes Alan Sullivan, an engineer for Ameren, as saying there were actually "over 300" holes drilled) but to reinforce them. While the original anchors were installed vertically, effectively increasing the downward force of the dam and increasing the frictional forces keeping the dam in place (Bagnell is a gravity dam), the new anchors will provide both vertical and horizontal force components.

Here is a drawing provided by Ameren:



The concrete work is a little less clear, but Ameren states they will be adding 66 million pounds to the basic structure, spillways, and top section. All which will add more weight and again create more downward force on the bedrock.

Bagnell Dam Structural Upgrades Begin in March 2017

By now, many have heard that Ameren will be investing $52 million dollars in upgrades to Bagnell Dam, but what exactly are they going to do?  Is the dam broken?

No, Bagnell Dam is not broken, or structurally deficient, but it could probably use a little work.  The last time Bagnell Dam had a major structural upgrade was in 1980 when 277 post-tension anchors were installed to secure the dam to the underlying bedrock.  Recall that Bagnell Dam is what is known as a gravity dam, meaning it is held in place by sheer weight. While this is a perfectly acceptable design methodology there are potential issues to contend with and the anchors set in 1980 were installed to insure the dam would not move from its position over time.

Ameren will be installing 68 more anchors along with additional concrete to reinforce the roadway deck from underneath, and also repair the top roadway deck itself.  The top deck work is more cosmetic than structural, but as anyone who drives across the dam on a regular basis knows, it looks bad. The condition of the roadway concrete gives the impression that the dam is in disrepair, appearances being what they are.

So what is a "post-tension anchor"?  How does it work to keep a dam in place?

Post-tension anchors, conceptually, are quite simple.  Bore holes are drilled through the dam and into the underlying bedrock with a tension cable running through the entire thing.  Once properly anchored, the cable is tightened, much like a giant bolt, to provide additional frictional force between the dam and the bedrock.  Simple, but as with all things, the devil is in the details.

Ameren won't say why the additional anchors are needed, there are many reasons to install such devices in dams, but the overall goal is strengthening.  The reasons for strengthening an existing dam vary but the two main ones are to meet new safety regulations or increasing a dam's water storage capacity.  Both of these reasons are unlikely since Bagnell Dam just went through a relicensing process which required extensive analysis of its condition, and Ameren cannot raise the operating level of the lake.  Is there any other reason for these anchors? Another possibility is the anchors provide additional structural strength for increased spillway capacity.  Given recent flood events in 2015 which resulted in extended periods of operations where flood gates were operated, Ameren may have discovered a vulnerability.  There is also the possibility that the anchors installed in the 80s may have issues with corrosion, a common problem with post-tension anchors. Any time you sink metal into wet bedrock, corrosion is a primary concern and some dams with these structures have had issues.

Regardless of the motivation, the addition of the anchors will simply help insure the dam is around for a long time.  The work is expected to take 18 months with no disruption to electrical generation, the impact on traffic flow however is unclear.

For those interested in the engineering details of all this, here's a link.

2016 Bagnell Dam Operations Summary

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.

Bagnell Dam Total Flow - 2015

Corrected.

November 2015 Lake Levels and Discharge

No power generation to speak of in the first half of November meant lake levels stayed virtually constant.  Rain and cold moved in and the lake reached full pool, nearly two and a half feet above the 5 year average.  Power generation is clearly seen in the latter part of the month as average generating discharge dropped the lake towards more average levels.

October 2015 Lake Levels and Discharge

October turned out to be the best boating month of the year! Ameren power generation was almost negligible with only five outflows of any consequence, leaving the Lake of the Ozarks comfortably above the 659 mark despite the lack of rain.  Calm winds and warm weather throughout the month made it a boaters dream. Wow!

The Flood of 2015

Update:  Things are back to normal.  Here's my final post.

July 1, 08:00: Floodgates are open, but not all the way.  Why?  Lake levels are as high as they've been in recent memory, now at 662.34ft and still rising.  Damage around the lake is already well underway and when the boats start moving in earnest during the holiday weekend things will get very bad indeed. Unless Ameren cranks open the floodgates much more, it is unlikely we will be back at normal levels within the next 24 hours, but the Osage can only take so much more.  Flooding in the Jefferson City area downstream is already pronounced.

All 12 Floodgates are open

Here's a chart of the last four days.  I left in the last two days of June as reference.  I'll be updating this throughout the day.

Notice that at 8am, things begin deviating from the average. The rain was coming down pretty hard and by 10am Ameren opened the floodgates 10% of capacity.  Judging by the current discharge of nearly 80,000 cubic feet per second, they've opened them to about 30% capacity since. At fully open, the Bagnell Dam is capable of releasing over 200,000cfs, but that hasn't happened since the 1940's and the effect was disastrous downriver.  The current flow rate is predictably devastating to the Osage River, rising nearly 12 feet in the past 24 hours.

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.

What Is the Meaning Of "Lake Levels"

The importance of lake levels extends far beyond just how "full" the Lake of the Ozarks is at any given time, it also establishes private property rights and project boundaries.  In short, lake levels establish boundaries between water and land, what is owned privately and what is considered managed by Ameren UE through federal licensing.

Lake levels are referenced to sea level, but what exactly is sea level?  The planet's oceans are not all the same height, for instance the absolute height of the Pacific Ocean is higher than the Atlantic Ocean, so it is important to establish exactly what "sea" we are using as a baseline reference. For the Lake of the Ozarks "sea level" was established by the "Mean Gulf Level" from Biloxi Mississippi.

The Gulf of Mexico is a large sea, typically differentiated from an ocean by being near and adjoining land, usually partially enclosed by it.  The gulf is certainly a large enough body of water to be influenced by tides which means establishing a single average (mean) level must be done by tidal stations, distributed over a large area of coastline. Measurements at these stations are made using vertical benchmarks positioned on land and therefore must take into consideration that the land itself also moves vertically over time.  Globally this effect can be quite pronounced as, for example, the coastline of the Gulf of Mexico is typically in a state of subsidence (sinking), effectively raising sea levels, while the Gulf of Alaska is rising, lowering sea levels, due to less weight on the land from melting glaciers (isostatic rebound).

The "Mean Gulf Level" was established by the Mississippi River Commission near the end of the 19th century, well before Bagnell Dam's construction.  As time goes by, and the relative sea level changes due to geological processes and rising sea levels due to climate change global warming*, it may become necessary to re calibrate what "lake level" actually means.

* 2017 Blogger's Note:  I see no point in trying to appease the climate change deniers, least of all by mincing words. It may be climate change in a general sense of the topic, but the actual trend is for a warmer planet, and that is the cause of rising sea levels. The world might be a better place if we stop getting our opinions from social media (this blog included), news outlets, or politicians. Try understanding at least some of the science of a warming planet for yourself rather than just pointing out that it still snows in the winter as evidence to the contrary. #thisshitisgettingold

April 2015 Lake Levels and Discharge Graph

With lake levels rising as early April rains appeared, Ameren went ahead and generated a good amount of power despite the mild temperature.  Levels quickly fell back to within seasonal average for the middle of the month and began the expected rise to summer levels by the end.  The last day of April matched the five year average exactly.

First Official "Dam Challenge" Time is set.

Apparently there is an effort to establish a standing record for making a dam to dam run as fast as possible.  Here's a video of the "record" run made last September.  188 mi (94 up, and back) in 2 hours 29 minutes and 49 seconds.  There's more info in the video notes.

It looked like a blast to me.

Here's a video at 4x speed looking forward.  If you ever wanted to see the entire lake in five minutes...

There's also a full length video.

How Much Electricity Can Bagnell Dam Produce?

This is a detailed analysis of the power generating capabilities of Bagnell Dam given known operational parameters.  What I've done is to analyze the performance of the dam, based on licensed flow rates, energy sales, efficiency analysis and the geometry of the dam itself.

The analysis avoids anything above high school algebra so it shouldn't be too hard to follow, but it is rather detailed.  In the end, we discover that the dam design matches well to flow rates for the Osage river basin but within licensed flow rates is still in fact capable of producing over 10% more energy than it currently does.

On a personal note, this took me far longer to do than I thought it would.  I wish I had paid more attention in my civil engineering class.

How Much Electricity Can Bagnell Dam Produce?

How much does Bagnell Dam weigh?

Bagnell Dam is what is known as a gravity type dam, meaning it is designed to impound water by shear size and weight.  Others, such as the Hoover dam, utilize load bearing shapes, typically curved, to reduce overall mass.

Bagnell Dam was built using 553,000 cubic yards of concrete, and although there is no fixed number for converting concrete volume into mass (due to the different types of concrete) a rough rule of thumb is 1cu.yd concrete = 2 tons of weight.

Therefore, 553,000cu.yds=1,106,000tons

As officially stated, we also have totals for the remaining structure:

Reinforcing steel (rebar) at 2,000 tons
Structural steel at 1,500 tons
Gates, trash racks and guides at 2,100 tons
Machinery for hydroelectric operations at 1,500 tons

For a grand total of 1,113,100 tons, or about 2.23 billion pounds!  Now that is a chunk of concrete. By comparison though, Hoover Dam weighs 6.6 million tons, or about 13.2 billion pounds, despite its mass reducing curved design which distributes the majority of the lateral load to the canyon walls.

Update: April 2017 - Work should begin soon on additional post tension anchors and 66 million pounds (about 33,000 cubic yards) of concrete.  That's a lot of concrete by any measure but only represents about 3% of the current weight.  It's hard to imagine that relatively small additional weight would make a significant difference.  The addition of 68 post tension anchors would seem to provide a greater impact insuring the dam never moves.

January Lake Levels Remain High

Despite a good start at the beginning of the month to begin drawing down the lake, levels remain high compared to the five year average by 2.5 feet.

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