This is interesting and hits close to home for me so to speak. A mountain and glacier has broken away and caused Meager Creek (in British Columbia Canada) to be dammed which has created a huge lake behind it. The creek joins the Lilloeet River and now the water is dropping in this river. The river eventually flows down into the Pemberton Valley aka Pemberton Meadow which is known for it's rich farmland. Not sure how many people live in the actually valley/meadow itself, however the town of Pemberton has about 2500 people.

The fear is if the now dammed creek gives away, it will cause a massive flood downstream and the damage could be catastrophic. This area is where I was last weekend and below I have posted a few photos of mine (taken last fall)

A couple of news links here and here. BTW, the photos in the first news link really shows the extent of the forest fire smoke effect from fires about 60 miles northeast of the area.

Google Map of the area Capricorn Mountain and Meager Creek is at the top left which flows into the Lillooet River. The town of Pemberton is to southeast along the valley.

This first photo taken along the Lillooet River. IIRC, Capricorn Mountain should be the high rocky right peak.


The Lillooet River and Pemberton Valley downstream of Capricorn Mountain which can be see off (left) into the distance.

Yipes. Please post updates if you have the time.

HJ

Teslin_, I saw the story earlier. The names were familiar but I didn't quite realize these were your stomping grounds.

Geez, you guys are getting hammered this year. Fire and flood, and nothing in between.

I suppose this is just past the peak of the annual melt? Lots of water flowing right about now? And I'm guessing that both towns and farms are on the high side of the flood plain (since the other option is 'blasted into the mountainside')? It all sounds like a recipe for trouble -- what we call the '100 year flood' around here.

Keep us up to date. National media only reports in detail when there are orphans crying beside their smashed homes, etc., etc.

-Doug

BTW, the Google map is quite amazing. Didn't know they had big-scale topos -- duh.

Doug:

You are correct, the Lilloeet river probably peaked 2-3 weeks ago, however as I seen it on last Saturday, it is still very high.

The Pemberton Valley is not very wide and there are number of farms/residences on both sides of the lower Lilooet river and it is these properties the initial concern is about. Depending on how big the newly created dam is upriver and what duration it may be there for and if gives way will provide a better answer on the severity of any flood damage. The overall problem if that dam decides to let go all at once is there is only the main road into the valley and it is a secondary 2 lane at that. At many places, the road is right along side the Lillooet River and it would not take much to have the river overflow it's banks in some places.

I know this area very well. At around the 17 km mark from the town of Pemberton is a turnoff to a 1 lane forest service road bridge which crosses the Lillooet River that takes you (NE and steeply) up into the Hurley River pass (where we were last Saturday). Depending on the outcome of the situation up river, if I were in that area, I would sticking close to that bridge and on the NE side of it. At least on that side, there are a few different FSR (Forest Service Roads) and trails that would take you to higher ground in a very short time. If that bridge gets taken out, the drive over the Hurley pass and over to the town of Lillooet is a long and adventerous drive by car and eventually before you reach Lillooet, you will be right in the middle of an active forest fire area...so you cannot really win...

Hopefully it will not come to this. Be interesting to see what is on the 5:00 pm (Pacific) news. I'll give an update after I watch.

We are planning to be up in that area on the Aug 21-22 weekend and will see if I can get some updated photos of what the mountain looks like now.

Okay, I watched the news coverage on a couple different broadcasts. The damage is much more massive then I ever thought it would be and is almost mind boggling.

I tried to keep some notes during the news and here is a summary:

- Slide is the result of a huge glacier breaking away which then caused the mud / land slide.

- The debris field is several km's long and 2 km's wide....and words cannot describe the damage.

- Estimated to be one of the biggest slides in recent PNW history.

- There were 2 slides. First smaller slide occured last night at 11:30 pm Pacific. Second slide ...which was the massive slide occurred early this am around 5:30 am local time.

- Slide is into Capricorn Creek which empties in Meager Creek. Meager is not flowing into the Lillooet River and causing the debris dam.

- Lillooet River is flowing in a new channel past Meager creek...which is good, however the river has dropped almost 2 feet overnight. This means there is a lot of water being held back which could have potential consequences.

- 5-6 km of FSR road completely gone. (I can almost confidently say that this road will not be rebuilt due to the remoteness of the area and related high costs.)

- This morning, some campers heard and seen the slide coming then jumped into their truck ahead of the mud/ice slide and were chased by the slide until they hit a FSR and were able escape from the path of the slide. (what a tale they will be able to tell !)

- 3 homes evacuated in upper river area.

- No other evacs planned yet as lower Lillooet river channel may be wide enough to accomdate the increased flow and debris if the mud and debris dam fails An official evac alert will be given around 7:00 pm. People should get ready though in case an evac is required on a moments notice.

here is a link to a high quality science blog that is covering this event.
http://daveslandslideblog.blogspot.com/2010/08/landslide-at-meager-creek-british.html
Dave's Landslide Blog is out of Durham University in the UK.if the earth slides any place in the world proffessor Dave will know about,from dirt over the road in California to river blocking slides in Pakistan or Canada.

Thanks CanoeDogs.

There was a full evac alert a couple of hours ago.

The Pemberton Valley and surrounding area is such beautiful country and I would be devastated if there is full scale flood there. The people who live along there would give their shirt off their back to you and now they could be close to loosing everything except their shirts...

Here is another photo of mine. Capricorn Mountain is the rocky peak on the right and this photo has a better view of the now mostly gone glacier

Too bad they can't drain off some of the water before it builds up to the point where the "dam" collapses. Once the water overtops the "dam", erosion or even total collapse may rapidly ensue, either of which might quickly release damaging amounts of water.

Of course there are "dams" formed by terminal moraines that have stood up to the pressures of dammed waters for centuries. Perhaps this will become a new recreational area. Dunno, but it does sound like an awful lot of debris came off that mountain. That amount of debris might be strong enough to hold back a lot of water provided that the "dam" doesn't get quickly eroded when water finally rises to the level where it overtops the "dam."

Of course, if there's a lot of ice in the debris, then, when the ice melts, it will leave voids, voids that I can only think would destabilize the "dam". Sounds like this might be a good prayer opportunity.

HJ

Jim..the landslide blog has quite a big section on the slide in Pakistan and the attempts to cut a drain into the head of the slide.very tricky work,they brought a crew in from China with experience working with the same problem there.from what i gather if you make the drain to big it starts a washout and the whole thing lets loose,too small and the river forms a lake and over tops the slide with the same result.from our point of view its a real BOB situation.

Looks like the danger has passed. There was an evac late last night of about 900 people who were allowed to return home just after 11:00 am today.

Apparently, the slide was an estimated 40 million cubic metres in size which makes it one of the largest in Canadian history.

More details here and if you read down the page, this quote states the continuing danger:

Options for clearing the mix of soil, rock and snow in the slide are limited by the lack of stability in the area of the slide. “It wouldn’t take much to drop another million cubic metres off the face of the peak that slide.”

Our previously made plans for going up into the area on Aug 21-22 are on hold until further notice...