1910 Redmond Dam on French Broad River near Marshall, NC

(Satellite)

In this video of the Hurricane Helen flooding, because the water is moving, you can easily see that the brown on the tracks in the background is water that is going around the dam.

Facebook Reel

This is the third example I've seen in 2014 teaching us that engineers need to pay attention to the height of the abutments of concrete dams. The first two examples I have seen are:

Rapidan Dam. This is an early photo. After a few days the bank was eroded underneath that house and all the way down to the downstream level. The house disappeared.

StarTribune, Aaron Lavinsky/Star Tribune via Dennis DeBruler

Nolichucky Dam. The TVA had to do repair work of the right abutment.

0:19 video via Dennis DeBruler

There are whitewater sports on this river. As an example of the impact of rain on this river basin, just an inch of overnight rain increased the flow from 2,800cfs to 5,500cfs. [BlueRidgeNow]

Facebook Reel

Facebook Reel

This is what a more normal flow looks like. 

Duke Energy posted
Marshall Hydroelectric Station is the perfect backdrop for fall. Nestled on the French Broad River in North Carolina, the station began operations in 1910. Quick start-up times make hydroelectric power ideal for providing electricity in a matter of seconds when demand is high. 

The island that we see in this photo appears to be under water in the third Facebook Reel screenshot above.

Ryan Phillips Photo

A good view of the hydraulic jump because of Hurrican Helene.

r/asheville, Hurricane Helene

I found a capacity figure of 5mw, but that seems too low. [GlobalEnergyObservatory, the GPS coordinates don't make sense.]

These are the flood waters that destroyed the Southern Depot in Marshall, NC.

Abandoned/MRL/NP 2022 Flooded Bridge over Yellowstone River near Livingston, MT

 (Archived Bridge Hunter; Satellite)

We already saw in Reed Point, MT, that the Yellowstone River inundated its flood plain, covered a main highway and threatened the town.

A Flickr photo showing the flood waters while the bridge was still intact.

"Built 1897, Relocated here 1918" It was damaged in the Spring of 2022 and removed in Aug 2022. The longest span in this 316' (96m) bridge was 155' (47m). [BridgeHunter]

Thomas Wentzel posted two photos with the comment: "A collapsed train bridge is shown along the Yellowstone River Wednesday, June 15, 2022, near Livingston, Mont."

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A reference on BridgeHunter indicates it was this bridge by MT-89.

Street View

Street View, Oct 2021

Street View, Aug 2022

Street View, Aug 2024

The bridge was pin-connected.

Street View, Oct 2021

At least the highway bridge survived the flood.

Kyle, Nov 2022

Global Earth, Sep 2020

I am surprised that it eroded on the inside of the bend in the river. The current is normally stronger on the outside shore of a bend and that is normally where the erosion happens.

Global Earth, Jun 2022

Global Earth, Dec 2022

1912 11mwNet Wilbur Dam on Watauga River east of Elizabethton, TN

(Satellite)

These high flows were caused by Hurricane Helene.

"According to the TVA, the headwater at the dam hit an elevation of 1970.2′. The elevation set a new pool of record by three feet, the TVA stated." [wjhl]

Elizabethton/Carter County Priority News & Alerts posted two photos with the comment: "Wilbur Dam as of 3 hours ago [Sep 28, 2024, 5pm ET]!!"

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Looking at the gaps above the gates, the gates are significantly higher above than they are below. This photo also shows why the water is so turbulent in the right-descending spillway---the side of the mountain protrudes into the spillway.  You can also tell how far open the gates are by the angle of the lower braces to the gates. They are horizontal above, but they are barely above their closed position below.

Charles Smith, Feb 2015

 

Facebook reel
[Whenever I see the word "today," I try to add the date. But I could not figure out how to get a date for a Facebook reel! It showed up in my feed on 9/30/2024.]

TVA
"The dam is 76 feet [23m] high and stretches 375 feet [114m] across the Watauga River."

Here is another example of where the gates have been raised just a little.

Edward Hyle, Feb 2014

This was uploaded as "TVA Watauga Dam Visitors Center," but I recognized it as the Wilbur Dam.

Jesse M, Mar 2022, cropped

1913-1972 Nolichucky Dam on Nolichucky River south of Greeneville, TN

(Satellite)

An aftermath of Hurricane Helene in Sep 2024.

"On September 27 at about 11:30 p.m. ET, out of an abundance of caution, TVA issued a Condition Red alert, which meant that a breach was imminent." As of 9am Sep 28, Local Emergency Management Agencies had ordered evacuations. As of 4pm, TVA rescinded the Condition Red alert because water levels were receding at about 1 foot an hour. "The Nolichucky Dam peak water elevation hit 1266.0’, which is 9.5 feet over the record elevation of 1256.5’ set on November 6, 1977. The 1.3 million gallons per second [174kcfs] flow rate at 11 p.m. on September 27, more than doubles the flow rate of 613,000 gallons per second [82kcfs] from the previous regulated release in 1977." [TVA_news] To put 174kcfs in perspective, I think the flow rate that wiped out the spillway of the Oroville Dam was about 100kcfs. A Knoxville News Sentinel summary said the "flow reached nearly twice Niagara Falls." But the article was behind a paywall.

0:19 video
This is the Nolichucky Dam in Greene County in East TN. TVA says the dam is still intact, but they continue to assess the situation. 🙏

I think this is the TVA video that was the source for the above post.

 

TVA posted

⚠️ Out of an abundance of caution, we have issued a Condition Yellow for Nolichucky Dam in Greene Co., TN.

A Condition Yellow indicates that the dam is approaching its threshold to withstand excessive floodwater, necessitating immediate action. The dam structure has not failed.

Local county emergency management officials are coordinating evacuations as appropriate.

Extreme rainfall from the remnants of Hurricane Helene is causing record river levels.

Facebook reel

 

I noticed that they are not letting traffic cross the bridge.

wjhl

This is a normal flow over the dam.

Street View, Mar 2023

This is the lowest flow I could find with Street View.

Street View, Nov 2023

This was the highest flow I could find with Street View.

Street View, Jul 2013

TVA
"The dam is 94 feet [29m] high and 482 feet [147m] long."
The hydroelectric equipment was removed in 1972 because the reservoir filled with sediment. I could not determine what the capacity was when it was built. It was built to generate electricity.

Normally, I can find a dam on a river by looking for a skinny line next to a fat line. But in this case the river is as wide below the dam as it is above the dam. That means the river is in a steep canyon.

Satellite

TVA posted five photos with the comment: "We continue to focus on the safety of Nolichucky Dam in Greene Co., TN. Heavy machinery is onsite, placing large rocks to stabilize the area the flood waters scoured away. We are also removing the old powerhouse because of the damage caused by flood waters - the facility hasn't been in service since 1972.
Dam Safety engineers and construction teams are conducting a thorough review of the area and will make any necessary repairs to the dam."

Brett Wanamaker shared

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Digitally zoomed to Facebook resolution

Oct 14, 2024:

TVA posted
Our Dam Safety team will perform a downstream inspection of the Nolichucky Dam in Greene County, TN, on Wednesday, Oct. 16, and if more time is needed, finish the work on Thursday, Oct. 17. The dam's small spillway gate will be opened on Tuesday to lower the reservoir so we can perform the inspection with no water flowing over the main spillway. The dam remains stable and secure.
Ernie Berry: It did not break. A lot of people reported it broke because there was so much water moving downstream. It was reported that 325+ million gallons flowed into Douglas with around 275 million coming from the noli. In places the noli was 1/2-3/4 mile wide and 20-30’ above normal flood height. No one alive today had ever seen the noli like it was that day.

TVA posted five photos with the comment: "Our dam safety experts conducted a thorough inspection of the Nolichucky Dam this week using high-tech equipment, including underwater remote-controlled cameras, LiDar laser measuring equipment, and aerial drones. Engineers will continue to evaluate the information, but the initial inspection determined no major damage to the dam structure. Construction crews continue to repair the dam’s right abutment, which was scoured by the historic flooding from #Helene."

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1916,1947 UP/C&NW+CPKC/Milwaukee Bridge over Mississippi River in St. Paul, MN

(no Bridge Hunter? no Historic Bridges; John A. Weeks III; Satellite)

This is one of the flood incidents of 2024.

According to a topo map and John Weeks, this is UP/C&NW/Minneapolis, St. Paul & Pacific (Omaha) and CPKC/Milwaukee Road. The locals refer to it as the Omaha bridge. A more official name is River Bridge #15. John explains that this structure was one of the original 15 bridges to span the Mississippi River. The first crossing here was built in 1869, and it was a wooden drawbridge.

 

River View, Aug 2016

A bobtail bridge always has a counterweight on the short end to balance the bridge over the pivot.

JohnWeeks
The bridge is 1,055' (322m) long with a navigation channel of 160' (49m).
"Despite a fair number of trains using this crossing, the bridge is maintained in an open position except when trains are using the bridge. The unusual feature of the swing span is that the pivot point is not in the middle of the bridge. Rather, the river section of the swing span is 185 feet [56m] long, while the other side is only 75 feet [23m] long. This feature is called an asymmetrical swing bridge [or bobtail bridge], and it is the only bridge like it on the Mississippi River.According to a local legend, once the bridge was erected, the owner of the land adjacent to the rail line objected to having the bridge swing over his land. To solve the problem, the railroad simply cut off that part of the bridge, and balanced it out with the large concrete slug that hangs off the back end of the swing span. The real reason for the non-symmetrical swing span is that the navigation channel is so close to the shore. The result is that half of the swing span would swing over dry land, so why span that dry land with expensive steel when cheap timber and cheap concrete would do the trick?" 
[John also describes the corporate history of the bridge.]

Another view of a normal river level.

JohnWeeks

Becky Haag posted two photos with the comment: "I finally got a fairly decent photo of the asymmetrical 1915 Omaha Swing Bridge and the approach in St. Paul this fall on a Padelford Riverboat cruise. It's still used by UP and we got a wave from the bridge tender."

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Andre Wehrle commented on Becky's post
Nice. I got some shots of it in 2021 also from a Padelford boat.

Becky Haag commented on her own post
My dad hit the jackpot on one of his rides. The river was low enough that they could make it without opening the bridge, but he said it was pretty close. He'd never seen the bridge closed, let alone have a train go over them.

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Flood of 2024

Compare the height on the piers to the river view at the top of these notes.

19:31 video @ 6:46