Anyone know what happened to Riffe Lake?

[ChesterDog206]

We went out to Riffe lake the year before last in April or may and hammered these beautiful 18" silvers that were biting everything we threw at them right at day break. My buddy got 2 on his 5wt. fly rod. It was a blast! The fish were beautiful (despite some internal parasites). I tried to go back last year and found there wasn't enough water to fish my spot. The lake was a trickle up by Taidnapam. I kept an eye on the water level on the Tacoma Power website, but they never filled the lake and It's been low ever since. I figured it had an impact on the local campgrounds so I called last week and left a message asking if the lake would fill this year. A gal called me back and said no. That it would remain the same due to work on the dam, but because of increased snow pack, it may be a bit higher then last year. Looking at the eroding dam in Oroville CA right now enforces the idea that dam maintenance is important, but I couldn't find any information on the Riffe project or it's expected completion. Anyone know any more details?? What a shame about those silvers. I feel like it was a really good fishery that may not be the same when all is said and done.

[Larry3215]

It could take years to recover. Im interested in details on the repair project too. I havent heard anything.

[Hunter757]

Here is some information on found online.

https://www.mytpu.org/tacomapower/about ... ck-dam.htm



2017 Riffe Lake levels
Based on new information about regional seismicity, the United States Geological Survey (USGS) recently revised its earthquake predictions for the Cowlitz River basin. Although the probability of a large earthquake is very low, the revisions showed an increase to the potential impact just on the spillways of Mossyrock Dam (not to the dam structure itself). To protect public safety, Tacoma Power has proposed to hold Riffe Lake’s elevation down approximately 30 feet lower than full (778 ft.) at least into the next decade. Approval by the federal agency that regulates the utility is pending.
Please note: The circumstances at Mossyrock Dam are significantly different than the current situation at Oroville Dam in Northern California. Tacoma Power is not reacting to a current situation – the operational changes are an abundant precautionary measure. There is no impending emergency at Mossyrock Dam and there is no structural damage.
Without a significant seismic event, which has a very low probability, there are no concerns about Mossyrock Dam. Mossyrock Dam is a concrete structure, while the Oroville Dam is an earthen structure. The spillways at the Oroville Dam sit on soil and bedrock, and are failing. At Mossyrock, the spillways rest on concrete, and, even when applying the revised seismic analysis, it is not predicted that an earthquake would compromise the dam – it would only impact the spillways. The mitigating response is keeping the lake level about 30 feet lower than full.
Public safety
Public safety is our top priority. Although there is a very low probability of the type of seismic activity that would cause the spillways to fail, we have a responsibility to operate in a way that limits the risk to the public. Keeping the lake level lower accomplishes that. There are no modifications to the operations at Mayfield Dam.
If we experience significant rainfall or a flood event, Tacoma Power may need to use the storage capacity of Riffe Lake to minimize downstream flooding by temporarily allowing the lake level to rise. After the risk of downstream flooding passes, we would then gradually lower the reservoir.
Seismic information
This is not an issue with the structure of the dam, but is related to the piers that hold the spillway gates in place. Mossyrock Dam is a unique design – a tall, double curvature arch with spillways located high in the middle of the dam. No concrete arch dams have failed due to earthquakes, however, preliminary analysis concluded that specific seismic events could render the spillway gates useless, which could cause considerable downstream flooding. Lowering the lake level will limit the impact.
We are looking at seismic retrofits. The development and implementation of possible solutions involves substantial analysis, planning and federal approval. The process required for making changes to a federally licensed hydroelectric dam is long and arduous.

[TrackerPro16]

While I understand the reasons it does suck. Riffe lake is fun to fish. Or was. Might still be. I have not been there for a couple years and it was pretty low when I went.

[Hunter757]

I agree been fishing there for 25 years. Lets hope the fish adapt and there is a boat launch to use but only time will tell.

[salmonkiller]

I fished it from a boat Memorial day weekend last year, We fished near Taidnapam it was VERY VERY slow!! I don’t know if the fishing ever improved after our visit… Ohh and the log boom was not set up yet at the Taidnapam boat launch so it was filled with drift wood... when retrieving my boat some driftwood got stuck on my brake line and broke it.. wahooo!!!!!

Hopefully this year is better…..

[ChesterDog206]

Thanks for all the info Hunter757.... Much appreciated!!

[Larry3215]

I wonder if any of the ramps will be usable with the lake 30 ft low?

[Hunter757]

Right now there all listed as Closed!!! Only time will tell at this point but right now the lake is over 60ft low and I really want to take a trip down and see it for myself. If we do go I will take some pictures and post them up.

[Smokeploe]

Was down at the dam this past Monday trying my luck nothing! The water level was appx 15-20 ft below the water level stick on the side of the support wall on the dam. Cold water, visability 5-8 ft.
Smokeploe

[Hunter757]

In the news: posting.php?mode=reply&f=2&t=23868


CENTRALIA, Wash. - Updated earthquake concerns for Mossyrock Dam, the tallest structure of its kind in Washington, have prompted Tacoma Power to commit to a new, reduced water level at Riffe Lake that will likely stretch well into the next decade.

The Chronicle reports the lower water level will be employed during the spring and summer months when mountain snow runoff is typically allowed to fill the reservoir.

By keeping less water behind the dam, Tacoma Power hopes to alleviate risks that might exist to downstream communities should an earthquake of at least 7.5 magnitude strike close to the dam.

The fear is that the upstream piers that direct water through the spillway could become damaged, or even break off, during a strong quake. That scenario would disable the typical spillway function and allow the lake to rapidly drain.

Representatives from Tacoma Power said that only the 65-feet tall, 90-feet long spillway piers are believed to be at risk during the projected earthquake event. Tacoma Power says there is no risk to the integrity of the main arched concrete dam structure, and noted that no dam of its kind has ever failed due to earthquake activity.

If a full capacity Riffe Lake reservoir were to drain through a damaged spillway, a flow of 230,000 cubic feet per second would inundate communities downstream.

Tacoma Power representatives said communities from at least Toledo to Longview would be affected. They referred to that worst case scenario as a regional flooding event. By maintaining a lower lake level, officials believe that even a complete failure of the spillway function would lead to a release of water that would not cause substantial flooding issues along either the Cowlitz or lower Columbia rivers.

Pat McCarty, generation manager for Tacoma Power, said there is no imminent danger and that the summer water level reduction is being done as a precaution for public safety.

He also said Tacoma Power's announcement has no connection to the situation at California's Oroville Dam, where authorities ordered a large evacuation last week.

"This is 100 percent about public safety. Frankly, the risk we are talking about is very slim but that was not a risk we were willing to take," McCarty said.