Montana Snowpack

[ndfinfan]

Based on this current map, snowpack doing ok right now...hopefully the next 90 days she keeps moving in the right direction. I'd sure like to see us move into another wet cycle, even if only for a short time!

 

[KDM]

Bet Juneau Alaska would like to send us some of their snow. Holy driftmakers batman do they have their share this year.

 

[Paddledogger]

Sure would be nice to see Sakakawea get up to at least 1842' this summer. I see today it is as 1828', so we need that snowpack % to increase a bit more. Otherwise ramp access will suck this summer. I thought I heard a meteorologist say a couple weeks ago that we likely will see a pattern shift to a wet/ snow outlook come late February into March across the north. Then and early spring in April. Fingers crossed...I sure hope I wasn't dreaming. Guess all we can do is hope for the best and go to all the boat/RV shows and drool over all the new 2026 stuff coming out. But this thing called a job, sure interferes with summer fun.

 

[v193]

Fort peck may keep it, i thought i heard they are doing work on the Garrison Dam this summer so wanted to keep levels low? or am i mistaken?

 

[tikkalover]

Garrison Dam Spillway Improvement Project​

The U.S. Army Corps of Engineers, Omaha District, completed a Dam Safety Modification Study in June 2023 at Garrison Dam, near Riverdale, North Dakota. The study evaluated what repairs or improvements are needed to address structural concerns at certain places at the project, primarily within the spillway. These concerns pose risks to USACE’s ability to operate the dam during extreme flood events. The Dam Safety Modification Study also recommended a risk management plan to support the expeditious and cost-effective reduction of the risk posed by these concerns. Recommendations include modifications to the spillway that collectively address dam safety concerns with modernized designs. Key elements of these recommendations include:

• the full replacement of the spillway’s drainage system to remove manhole covers from inside the spillway to prevent the covers from dislodging during future spillway operations.
• placement of a reinforced concrete overlay in the spillway chute and stilling basin to ensure the spillway can safely pass extreme flows
• armoring the area behind the spillway chute walls to reduce potential for erosion during extreme flows
• raising the spillway abutment monoliths to prevent overtopping which can lead to erosion and failure of the structure
• constructing a deflector beam to deflect the overflow from spillway gates
• modifying the gates’ trunnion hubs to ensure they are structurally sound, and
• improving the system that deices the gates so they remain operational during winter conditions.

Over approximately the next six years, USACE will conduct field investigations to collect data to inform the detailed design and develop plans and specifications that are necessary to award a contract to complete these recommendations. As of 2023, construction is anticipated to begin in 2029 and take several years to complete.
In the near term, USACE also plans to construct an additional line of drains on the dam’s west abutment to address a slope stability and seepage concern that was evaluated in the study. Construction could begin in 2025 and would last one season.

 

[dblkluk]

Based on this current map, snowpack doing ok right now...hopefully the next 90 days she keeps moving in the right direction. I'd sure like to see us move into another wet cycle, even if only for a short time!

This map doesn't tell the whole story. A large majority of this snowpack is at very high elevations. Unless we start seeing snow at lower elevations, its gonna take a long time before Sak sees much for run off this year.

 

[Allen]

That's all fine and dandy for now that the headwaters area is around 100% of normal, but you have to put that into a little context. We are not quite halfway through the winter and we usually expect the snowpack to be about 35-40% of the total it will receive during the snow accumulation season. So, basically...the headwaters have only 35-40% of what is should have come roughly April (when the snowpack peaks).

As far as Garrison Dam work, I am not aware of any need to lower Lake Sakakawea to accommodate the upcoming work. Essentially, updated Probable Maximum Flood (PMF) studies have suggested the dam needs to be able to pass almost 1.2 million cubic feet per second to avoid losing the dam. The dam is currently able to pass a little under 900,000 cfs. The actual spillway modification doesn't start this summer, I want to say it's 2028, or later and will take a few years to complete. The plan is to expand the emergency spillway to accommodate the expected PMF and will be quite the undertaking.

If there's other maintenance that will require lower water levels, I am not in the loop on that.

For reference, the maximum flow out of Garrison Dam in 2011 was around 152,000 cfs. A PMF on the Missouri would be nothing short of hell for the Missouri River corridor through ND. Lastly, since 1929, there have been seven floods on the Missouri River bigger than the 2011 event as measured at Bismarck, all before the construction of Garrison Dam.

Here's the full peak streamflow data for Bismarck.https://nwis.waterdata.usgs.gov/nwis/peak?site_no=06342500&agency_cd=USGS&format=html

 

[BDub]

52 must have been whopper!

 

[Allen]

52 must have been whopper!

Indeed, my understanding of that one is that a large ice jam formed up in the Wilton and then catastrophically failed. Of course, that was the year before Garrison Dam went operational.

 

[Bfishn]

Hopefully this holds true. We need all the water we can get at Sak.

 

[Bfishn]

That's all fine and dandy for now that the headwaters area is around 100% of normal, but you have to put that into a little context. We are not quite halfway through the winter and we usually expect the snowpack to be about 35-40% of the total it will receive during the snow accumulation season. So, basically...the headwaters have only 35-40% of what is should have come roughly April (when the snowpack peaks).

As far as Garrison Dam work, I am not aware of any need to lower Lake Sakakawea to accommodate the upcoming work. Essentially, updated Probable Maximum Flood (PMF) studies have suggested the dam needs to be able to pass almost 1.2 million cubic feet per second to avoid losing the dam. The dam is currently able to pass a little under 900,000 cfs. The actual spillway modification doesn't start this summer, I want to say it's 2028, or later and will take a few years to complete. The plan is to expand the emergency spillway to accommodate the expected PMF and will be quite the undertaking.

If there's other maintenance that will require lower water levels, I am not in the loop on that.

For reference, the maximum flow out of Garrison Dam in 2011 was around 152,000 cfs. A PMF on the Missouri would be nothing short of hell for the Missouri River corridor through ND. Lastly, since 1929, there have been seven floods on the Missouri River bigger than the 2011 event as measured at Bismarck, all before the construction of Garrison Dam.

Here's the full peak streamflow data for Bismarck.https://nwis.waterdata.usgs.gov/nwis/peak?site_no=06342500&agency_cd=USGS&format=html

https://water.noaa.gov/gauges/06342500

 

[Allen]

Another way to graphically look at it. Holy Hannah, this winter is flying by.

 

[Maddog]