Wis. Dell's Lake Delton drained

[vintner Super Moderator Find all posts View Profile Close vintner]

Storms and flooding have done damage to the Lake Delton banks, and this man made lake is now gone. It has drained into the Wis. River.

Lake Delton is a big part of Wisconsin Dells and the tourism that supports the area. For those in the Minneapolis and Chicago area (and beyond) that travel to that area for our getaway spot, this is sad news. It is of course much worse for those who have lived on the shores of the lake. Many have lost their homes.

Bruce, hope you read and are able to add to this information.

I have clipped a bit of an article on the web along with the link. Pictures are amazing, but I have yet to figure out how to post them here.

Lake Delton...Gone!! | Newsradio 620 - Milwaukee, Wisconsin News, Talk, Sports, Weather | Local Headlines

LAKE DELTON, Wis. (AP) -- Residents will continue clean up efforts Tuesday and officials will start tallying the damage in the aftermath of severe flashing flooding across the state.

An engineer assessment team from the Wisconsin National Guard will be at Lake Delton on Tuesday to determine what equipment and supplies will be needed to begin repairs after the 245-acre lake washed out a highway embankment, forcing a new channel to the Wisconsin River.

The water destroyed lakefront homes and took a chunk of the local tourism industry with it on Monday.

A key part of the Wisconsin Dells tourism area, the lake overflowed after two days of rain and was empty and dry by Monday afternoon, said Thomas Diehl, a Lake Delton village trustee.

Local residents said three lakefront homes floated downstream and disappeared into the water, and the foundations of two other homes were destroyed. Nobody was injured and the homeowners either evacuated or were not there, residents said.

[vintner Super Moderator Find all posts View Profile Close vintner]

The Tommy Bartlett Water Show has cancelled the water portion of the show. The show is known for great trick water acts, boat jumps, skiing, etc. Now that the lake is gone...so is the show. They will continue to do the on shore acts.

This is going to kill the Wisconsin Dells area. Until they get that lake rebuilt and refilled, it is going to drop tourism in that town.

[wackymother Senior Member Find all posts View Profile Close wackymother]

That is so sad. I hope they are able to rebuild quickly.

[urple2 Senior Member Find all posts View Profile Close urple2]

Thanks for the updates.

I'm heading there (Wyndham Tamarack) on July 4th. Hoping to make the best of it.

[T. R. Oglodyte Moderator Find all posts View Profile Close T. R. Oglodyte]

From the pictures and the story it appears the lake was impounded without providing a spillway. If that's the case, government agencies were remiss in not requiring that a proper spillway be provided - or perhaps the legislature was remiss in not creating authority to regulate impoundments.

[bnoble Senior Member Find all posts View Profile Close bnoble]

Here is an article with some additional details:

JS Online: Swollen by rain, Lake Delton nearly empties, wrecking homes, damaging tourism hopes

There is a graphic that shows where the embankment failure happened.

[vintner Super Moderator Find all posts View Profile Close vintner]

How long to rebuild a lake?
Can they get the banks rebuilt this year and start filling?
You have to have good lake and bank structure before you start building homes again.

Can the lake be a filled lake again by next spring? Will it go to fall of 09 before the lake is in shape? Houses could be built in 2010, if everything goes well.

[PigsDad Senior Member Find all posts View Profile Close PigsDad]

The only houses affected were the ones in the washout area, right? Why would you want to rebuild there? If they were smart, they would never allow any rebuilding in the washout area, and construct a proper spillway there that would prevent a catastrophe like this again.

Kurt

[vintner Super Moderator Find all posts View Profile Close vintner]

The only houses affected were the ones in the washout area, right? Why would you want to rebuild there? If they were smart, they would never allow any rebuilding in the washout area, and construct a proper spillway there that would prevent a catastrophe like this again.

Kurt

I don't know if your statement is entirely true.

I am not positive the wash out area had houses as it was next to a road. It must have been near the new outlet, but not in front of the outlet.

A lake that turns into a river is going to (likely) destroy houses on the side banks as well as what was in front of its path. There was so much water in the flood, that the lake banks, or more properly shore, were so soggy and damaged before the water started to flow away. They just gave way as part of the lake draining.

The lake did have a dam which did control the water level. This is not like a flood area in the Mississippi Delta, this is a (normally) stable lake with an outlet. But, you dump a lot of rain, flood it and have a wall failure, you are going to have damage. Will it ever happen again? I would not bet on it, but I can’t prove one way or another.

People build in California all the time, there are earthquakes and they are more likely to happen than that lake ever flooding again.

I think it was one of those once in a lifetime events that planning (dam control or extra spill gates) may help reduce or eliminate from happening again.

[T. R. Oglodyte Moderator Find all posts View Profile Close T. R. Oglodyte]

JS Online: 3 problematic dams haven't been checked since '93

So the dam has a spillway and is intact. Having never been to the Dells, I have to do a bit of speculating here, based on the maps and geologic information in the news stories linked above.

It appears that there is a long sand dune running parallel to the Wisconsin River. A stream that joins the Wisconsin River cut a water gap in the in sand bar so that it could reach the Wisconsin River. Lake Delton was created by building a dam to close that gap in the sand dune.

With the gap now closed by the dam the sand bar is serving as a water barrier, holding back the lake water. In a geotechnical sense, the dam isn't just the man-made structure closing the gap; after the gap is closed the entire sand dune - both man-made structure and natural sand deposit - is the dam. Or you could consider the whole thing a levee.

Sand is a poor dam material. It transmits water readily and if seepage develops it erodes and leads to "piping" through the dam. Once piping starts the dam erodes quickly and catastrophic failure ensues.

++++++++++++

A key factor is that seepage through a dam cannot be allowed to daylight near the toe of the dam. If seepage starts daylighting, boils will likely soon develop and piping failure will follows.

Since sand is pretty permeable, I would imagine that there was significant continuous seepage out of the lake through that sand bar at all times - the rainfall wouldn't affect that. Under normal conditions the ground between the sand dune and the Wisconsin River was sufficiently permeable to carry that seepage underneath the toe of the sand dune and away towards the Wisconsin River.

When rain falls the rain water infiltrating into the soil adds to the water seeping through the sand dune that must be conveyed away. With the heavy rains, it's likely that the combination of seepage plus rainwater infiltration created more groundwater flow than the ground could handle, causing the groundwater level in the soil between the sand dune and the Wisconsin River to start rising. As the groundwater level got close to the ground surface at the base of the sand dune, conditions were set up for seepage to daylight at the toe of the dune. Sand boils likely started developing at the toe of the sand dune.

Once the sand starts boiling the boil becomes a path of least resistance, so more water starts flowing into the boil. That increases the amount of boiling, which further decreases the resistance, which increases the flow, which causes more boiling, which ....

There is a some warning when the boiling first develops, but the rate and intesity of boiling increases geometrically as the piping grows. At some point the piping removes material so quickly that the residual strength of the soil is lost and there is a sudden slumping followed by washout.

Had someone been looking they would have seen the sand boiling for before the collapse occurred. It's likely no one was looking so the slumping occurred without warning.

++++++

If my suppositions above are correct recreating the lake will be expensive. You can just repair the breach because that just moves the next washout to a new location. The entire length of the sand dune will likely need to be strengthened.

[PigsDad Senior Member Find all posts View Profile Close PigsDad]

I don't know if your statement is entirely true.

I am not positive the wash out area had houses as it was next to a road. It must have been near the new outlet, but not in front of the outlet.

A lake that turns into a river is going to (likely) destroy houses on the side banks as well as what was in front of its path. There was so much water in the flood, that the lake banks, or more properly shore, were so soggy and damaged before the water started to flow away. They just gave way as part of the lake draining.

The articles and pictures I saw stated the only houses with damage around the lake were the ones in the washout area. The lake did not turn into a river -- it just simply drained through the washout area. I think the total number of houses damaged was on the order of 6 or so. See this link for a good map.

T.R. probably has the best explanation. If that whole side of the lake were it parallels the river is one giant sand bar, then there is a lot of work to be done. Building a house on sand is indeed dangerous, as those homeowners have now discovered...

Kurt

[T. R. Oglodyte Moderator Find all posts View Profile Close T. R. Oglodyte]

If that whole side of the lake were it parallels the river is one giant sand bar, then there is a lot of work to be done. Building a house on sand is indeed dangerous, as those homeowners have now discovered...

Kurt

The main dam is visible on the left side of the photo.

The entire area from somewhere off the top side of the picture to somewhere below the bottom is presumably the sand deposit. The washout did occur at what would appear to be the narrowest point.

I see nothing in this photo that would change any of what I posted above.

[rapmarks Moderator Find all posts View Profile Close rapmarks]

one of those lost homes beonged to our friend's son. it is devasting. 93% of the businesses in the Dells were not affected by this. the biggest hit will go to the Tommy Bartlett Ski, Sky and Stage show, which will become a ski and stage show. The Ducks will change their route. the 26 businesses around the lake will lose some business, no water sports. They will get this fixed. The Dells people have a lot of political influence int he state and know how to gt things done.

[brucecz Moderator Find all posts View Profile Close brucecz]

Sorry, I somehow missed this string. But I see other members provided excellant information.

Sorry to here about Rapmarks sons friend home.

From what I heard from the resort was that there was a bit of a problem with the cable reception.

We may be going up the second half of the 4th of July week or the week after south of the Dells at Summer Oaks.

Again, sorry that I somehow over looked this string. We got a little busy this past week with the big doings for my brides mothers 90th birthday plus buying another timeshare. We now have 3 that we are buying in the closing process and 2 that we are selling in the closing process. WE were pretty busy with over timeshare related stuff.

What you may find a bit interesting is 5 of our 12 Fourth of July weeks rentals in the Dells area rented out in the last 10 or so days leaving only one left.

I just say maybe the Dells area is a traditional summer vacation place that hell or high water will not stop very many from doing their summer vacation there.

One thing I hear fairly often is that they first visited there when they were children and that they have very fond memories.

Bruce

[vintner Super Moderator Find all posts View Profile Close vintner]

...I just say maybe the Dells area is a traditional summer vacation place that hell or high water will not stop very many from doing their summer vacation there.

One thing I hear fairly often is that they first visited there when they were children and that they have very fond memories.

Bruce

I wonder if it was hell or high water and then more hell and no water?

I remember the dog jumping between the rocks, that was decades ago. I love the Dells, so much to do. I remember going to the Standing Rock Indian dance. I don't believe it is called that and is not located there anymore, but thought it was cool.