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[clarki]

This time last year, the Skagit region was at 27% of normal and come summertime there was no Ross Lake this side of the 49th. This year the Skagit region is at 22%…

It’s interesting that in 2022, the Skagit region’s “% of normal” was similar to adjacent regions, but in the three years it is a fraction of adjacent regions.

[SuperBobby]

This time last year, the Skagit region was at 27% of normal and come summertime there was no Ross Lake this side of the 49th. This year the Skagit region is at 22%…

It’s interesting that in 2022, the Skagit region’s “% of normal” was similar to adjacent regions, but in the three years it is a fraction of adjacent regions.

I certainly can't prove it but I have some doubts about the accuracy here....especially with what I bolded in your post. I almost wonder if something in the data has been missed, overlooked, or just contains errors. The way pacific storms come in and bring snowfall to the south coast is almost identical to how it works in the Skagit region. The interior's dry barrier doesn't start until you get to Allison Pass. The Skagit region is entirely west of that and is in the coastal range.

And especially as someone who fishes the Skagit every year.....this doesn't seem right. In all my memory, if the Chilliwack/Vedder was running high on opening day (July 1st), then the Skagit would also be running high on opening day (July 1st).....and as the summers progress into September, the Skagit and the Chilliwack/Vedder are almost identical in going from high to fishable to low water conditions each and every year.

So yeah.....I'm questioning the data.

[RalphH]

The % for each regional is relative to the historical average for each specific region. Some regions such as the Skagit (the smallest watershed region in the Province)  and the West Road Chilcotin are notably low compared to their respective historical averages. If you look at the Boundary Region it has the highest % of average for the Province in what is a dry zone. Similarly it was very close to average last year but had dry years with low pack just before.  Can't tell you what's up with the Skagit or the others for that matter.

[clarki]

I certainly can't prove it but I have some doubts about the accuracy here....especially with what I bolded in your post. I almost wonder if something in the data has been missed, overlooked, or just contains errors. The way pacific storms come in and bring snowfall to the south coast is almost identical to how it works in the Skagit region. The interior's dry barrier doesn't start until you get to Allison Pass. The Skagit region is entirely west of that and is in the coastal range.

And especially as someone who fishes the Skagit every year.....this doesn't seem right. In all my memory, if the Chilliwack/Vedder was running high on opening day (July 1st), then the Skagit would also be running high on opening day (July 1st).....and as the summers progress into September, the Skagit and the Chilliwack/Vedder are almost identical in going from high to fishable to low water conditions each and every year.

So yeah.....I'm questioning the data.

It's possible the data is wrong, but I don't think so. And here's why...

I geeked out a little bit and correlated the data from the BC snow surveys https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/drought-flooding-dikes-dams/river-forecast-centre/snow-survey-water-supply-bulletin with the data from USGS and the height of the Ross Lake reservoir. https://waterdata.usgs.gov/nwis/uv?site_no=12175000&legacy=1

My hypothesis/assumption was that there should be a positive correlation between the snow levels in the Skagit watershed and the height of Ross Lake... and there is

For reference, normal Ross Lake elevation varies from 1475 to 1602 feet (above sea level)

Year               Ross Lake height (ft).                        Skagit snow level (% of normal)
2024                             1587                                                          27
2023                             1584                                                          73
2022                             1602                                                          90
2021                             1602                                                          116
2020                             1602                                                          148
2019                             1566                                                          51
2018                             1602                                                          150

So if the snow survey data was wrong, I expect that we wouldn't see a relationship between the Ross Lake and the Skagit snow pack but in the years (2019, 2023, 2024) when there is well below normal snowpack, Ross Lake is well below full pool. And in the other years when there is lots snow, Ross Lake is approaching full pool. 

Just two sets of data, a rudimentary comparison, and some broad assumptions, but your personal experience on the river notwithstanding, I don't think the data is incorrect.

Additionally, I suspect that the Ross Lake reservoir managers from Seattle Power and Light are monitoring the Skagit snowpack to inform how they manage reservoir. I don't think they would tolerate incorrect data from BC. Just a guess...
       
Edit: correct a number I had wrong

[SuperBobby]

It's possible the data is wrong, but I don't think so. And here's why...

I geeked out a little bit and correlated the data from the BC snow surveys https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/drought-flooding-dikes-dams/river-forecast-centre/snow-survey-water-supply-bulletin with the data from USGS and the height of the Ross Lake reservoir. https://waterdata.usgs.gov/nwis/uv?site_no=12175000&legacy=1

My hypothesis/assumption was that there should be a positive correlation between the snow levels in the Skagit watershed and the height of Ross Lake... and there is

For reference, normal Ross Lake elevation varies from 1475 to 1602 feet (above sea level)

Year               Ross Lake height (ft).                        Skagit snow level (% of normal)
2024                             1587                                                          27
2023                             1584                                                          22
2022                             1602                                                          90
2021                             1602                                                          116
2020                             1602                                                          148
2019                             1566                                                          51
2018                             1602                                                          150

So if the snow survey data was wrong, I expect that we wouldn't see a relationship between the Ross Lake and the Skagit snow pack but in the years (2019, 2023, 2024) when there is well below normal snowpack, Ross Lake is well below full pool. And in the other years when there is lots snow, Ross Lake is approaching full pool. 

Just two sets of data, a rudimentary comparison, and some broad assumptions, but your personal experience on the river notwithstanding, I don't think the data is incorrect.

Additionally, I suspect that the Ross Lake reservoir managers from Seattle Power and Light are monitoring the Skagit snowpack to inform how they manage reservoir. I don't think they would tolerate incorrect data from BC. Just a guess...
     

The information you provided is probably good, but without the data from Seattle Power and Light on when... and how much drawdown is happening.....the date you provided is incomplete and therefore not fully reliable. You will find with most hydro dams that there isn't always an exact pattern of when they take from the reservoirs or build up the reservoirs. Regardless of snowpack, some months they take more and some months they take less. Then there is also rainfall totals that need to be taken into account as well.

[RalphH]

it's been comparably as low the previous  year so without any other evidence it doesn't make sense top dismiss the reading as wrong .