Funky Flows

[GeekOfAllTrades]

Hey y'all. I'm still in the beginning of learning how to read flow data and how that affects my fishing plans, so I have a question for the more experienced folks on the forum. Is this flow pattern normal? Or some glitch in the data?

I'm aware of a few patterns like seasonal runoff, Post-rainfall swell of rivers, and on dammed systems the occasional release if a reservoir needs it but this just seems funky to me. A ~2000 cfs jump in a little under 2 hours and subsequent fall a little later in such a consistent pattern seems like it might be harmful to aquatic life in the river system? Did the latest batch of storms really throw so much water into diablo lake that they need to release a whole bunch of water in bursts? Would love to hear people's thoughts.

 

[Buzzy]

Just guessing: power generation during peak demand.

 

[DimeBrite]

Humans use more electricity during daylight hours and less during sleep periods at night. The dam releases water to generate power accordingly.

 

[Jake Watrous]

A ~2000 cfs jump in a little under 2 hours and subsequent fall a little later in such a consistent pattern seems like it might be harmful to aquatic life in the river system?

Dams harmful to aquatic life? Wha?

 

[GeekOfAllTrades]

Dams harmful to aquatic life? Wha?

Lol set myself up for that one. Agreed wholeheartedly.

 

[GeekOfAllTrades]

Just had a realization that the pattern started back on the 15th when we had the relative scorcher of a weekend. Probably just early (and abundant) runoff from all the drainages up there into ross, diablo, and Newhalem. So that's my new guess.

 

[krusty]

Unless restricted to maintain minimum flow for protection of fisheries, dams are managed on the basis of energy generation to meet demand, pool level requirements for transportation/recreation, and preparation for anticipated seasonal runoff.

 

[Salmo_g]

What you see from the Marblemount gauge, and at Newhalem as well, is the coordinated operation of Seattle City Light's Ross, Diablo, and Gorge Dams to meet peaking power demands as described by others' posts above. Sometimes Seattle is able to run Gorge flat during the spring, which benefits juvenile salmon fry by reducing gravel bar stranding. It's actually a big deal, and the fluctuations any more are significantly less than they used to be prior to a 1991 flow settlement agreement. The current relicensing proceeding should be focused on reducing the amount of daily vertical fluctuation even more. I continue to see stranded salmon fry in the spring months when they are cycling the flow like that, even thought the downramping rate has been reduced.

 

[Smalma]

The others have covered the cause of those sharp daily flow changes. It is not uncommon to see those kinds of daily flow changes in rivers affected by snow or glacier melt run offs, see the Sauk at Sauk during say July. However those are mild compared to those we see being generated by Seattle light. Salmo-g covered the potential fry stranding with those falling flows. However there are impacts (largely on aquatic insects) that can be displaced by those sudden rises. This past week on the front end of those "upticks" in flows in about 25 minutes the river rose 1.12 feet and flows increased from 2,680 to 4,700 cfs. On the Sauk those rises are typically a few inches and it takes 9 or 10 hours form minimum to maximum flows, the aquatic life has developed strategy to survive those changes. The cumulative effect of those daily tides can be profound on the insect populations. One study in the mid-1970s found roughly a 10 fold decrease in maximum insect densities. This lack of insects and other related to hydrograph changes seems to be limiting the ability support salmonid parr (steelhead and Chinook and to a lesser extent bull trout).

Seattle's "green" PUD is not so much for those parr. Somehow it seems if the number of parr are limited the number of returning adults are also limited.

curt

 

[Pink Nighty]

The others have covered the cause of those sharp daily flow changes. It is not uncommon to see those kinds of daily flow changes in rivers affected by snow or glacier melt run offs, see the Sauk at Sauk during say July. However those are mild compared to those we see being generated by Seattle light. Salmo-g covered the potential fry stranding with those falling flows. However there are impacts (largely on aquatic insects) that can be displaced by those sudden rises. This past week on the front end of those "upticks" in flows in about 25 minutes the river rose 1.12 feet and flows increased from 2,680 to 4,700 cfs. On the Sauk those rises are typically a few inches and it takes 9 or 10 hours form minimum to maximum flows, the aquatic life has developed strategy to survive those changes. The cumulative effect of those daily tides can be profound on the insect populations. One study in the mid-1970s found roughly a 10 fold decrease in maximum insect densities. This lack of insects and other related to hydrograph changes seems to be limiting the ability support salmonid parr (steelhead and Chinook and to a lesser extent bull trout).

Seattle's "green" PUD is not so much for those parr. Somehow it seems if the number of parr are limited the number of returning adults are also limited.

curt

Curt-

In your opinion or viewpoint, is there a way to meet peaking power demands without spiking and dropping the flows? Do you know if the spiking is "the only way to meet demand" or if it is " the most profitable way to meet demand?"

You've done more to educate myself (and many others) on the effects of SCL dams on the Skagit than anything else combined, thank you for speaking to it.

 

[GeekOfAllTrades]

Thanks everyone for the replies and explanations. I had no idea about the history of the dams' operation and that 1991 deal. I had kinda assumed something to the effect Curt was describing where the drastic change in flows is the root of the problem, not necessarily how much flow but the rate of change if you will. But wasn't sure how exactly it manifested.

Adjacently, for a short time I worked as an engineer at a "New" Nuclear power startup called Terrapower in Bellevue. Lots of fellow outdoors-people and eco-minded folks I worked with there were of the opinion that the future of power generation needs to be nuclear (for obvious reasons). I kinda hold that same opinion. Yes it is scary if something goes wrong, but the alternatives that are renewable struggle with the whole "peak demand" problem so...

Anywho, thanks again. Always lots to learn from this crew.

 

[Salmo_g]

Curt-

In your opinion or viewpoint, is there a way to meet peaking power demands without spiking and dropping the flows? Do you know if the spiking is "the only way to meet demand" or if it is " the most profitable way to meet demand?"

You've done more to educate myself (and many others) on the effects of SCL dams on the Skagit than anything else combined, thank you for speaking to it.

Not meaning to speak for Curt, but I have some experience regarding this topic. Hydropower dams with storage reservoirs, contrasted with run-of-the-river dams, are "THE PREFERRED" alternative for meeting peak power demands because they can be turned from full off to full on to full off in about two minutes. The only other energy producer that can do this is gas combustion turbines. The way to do this without ramping the river up and down on the downstream side of a dam's powerhouse is to have the ability to use the lowermost dam in a series as a re-regulating dam that releases a more or less steady flow while storing water from upstream dams during those peak discharges so that all or most of the undesirable fluctuation occurs in the re-regulation reservoir pool.

The problem at Skagit is that Gorge has very little storage potential. So it operates almost as a run of river dam, discharging whatever flow comes in. Seattle would need to use both Diablo and Gorge to effectively re-regulate peaking generation flows from Ross Dam. As I recall, Diablo has about 12' of active storage that could be used to re-regulate. But Seattle uses both Diablo and Ross for peaking power needs. If I were working on the current relicensing proceeding, I'd be going after this as the agencies have an additional tool in their negotiating toolbox - the ESA listed species - that they didn't have in 1991.

 

[Salmo_g]

but the alternatives that are renewable struggle with the whole "peak demand" problem so...

Nuclear is like coal in that it is generally used as "base loading" for energy production. It lacks the intrinsic ability to rapidly ramp up or ramp down on the amount of generation. Unless the technology has changed.

 

[Pink Nighty]

Not meaning to speak for Curt, but I have some experience regarding this topic. Hydropower dams with storage reservoirs, contrasted with run-of-the-river dams, are "THE PREFERRED" alternative for meeting peak power demands because they can be turned from full off to full on to full off in about two minutes. The only other energy producer that can do this is gas combustion turbines. The way to do this without ramping the river up and down on the downstream side of a dam's powerhouse is to have the ability to use the lowermost dam in a series as a re-regulating dam that releases a more or less steady flow while storing water from upstream dams during those peak discharges so that all or most of the undesirable fluctuation occurs in the re-regulation reservoir pool.

The problem at Skagit is that Gorge has very little storage potential. So it operates almost as a run of river dam, discharging whatever flow comes in. Seattle would need to use both Diablo and Gorge to effectively re-regulate peaking generation flows from Ross Dam. As I recall, Diablo has about 12' of active storage that could be used to re-regulate. But Seattle uses both Diablo and Ross for peaking power needs. If I were working on the current relicensing proceeding, I'd be going after this as the agencies have an additional tool in their negotiating toolbox - the ESA listed species - that they didn't have in 1991.

Thank you for that detailed response. Hopefully the next agreement recognizes this.

 

[Pink Nighty]

Not meaning to speak for Curt, but I have some experience regarding this topic. Hydropower dams with storage reservoirs, contrasted with run-of-the-river dams, are "THE PREFERRED" alternative for meeting peak power demands because they can be turned from full off to full on to full off in about two minutes. The only other energy producer that can do this is gas combustion turbines. The way to do this without ramping the river up and down on the downstream side of a dam's powerhouse is to have the ability to use the lowermost dam in a series as a re-regulating dam that releases a more or less steady flow while storing water from upstream dams during those peak discharges so that all or most of the undesirable fluctuation occurs in the re-regulation reservoir pool.

The problem at Skagit is that Gorge has very little storage potential. So it operates almost as a run of river dam, discharging whatever flow comes in. Seattle would need to use both Diablo and Gorge to effectively re-regulate peaking generation flows from Ross Dam. As I recall, Diablo has about 12' of active storage that could be used to re-regulate. But Seattle uses both Diablo and Ross for peaking power needs. If I were working on the current relicensing proceeding, I'd be going after this as the agencies have an additional tool in their negotiating toolbox - the ESA listed species - that they didn't have in 1991.

Thank you for that detailed response. Hopefully the next agreement recognizes this.

 

[Salmo_g]

Thank you for that detailed response. Hopefully the next agreement recognizes this.

Sadly, I don't think they are focusing on this at all. The big push in negotiations appears to be for fish passage around the dams, which is likely to spend a whole lot of money and not produce many, or any, additional fish. But I digress.

 

[Brian Miller]

Hey y'all. I'm still in the beginning of learning how to read flow data and how that affects my fishing plans, so I have a question for the more experienced folks on the forum. Is this flow pattern normal? Or some glitch in the data?

If you are also looking for more generalized information on how to use CFS flow data to plan trips, I posted some thoughts here...

Basic Survival Skills for a Flyfisherman Just Learning to Swim

I am a shit swimmer. #1 rule is don't panic. Me too. I can swim ok, but swimming itself especially for leisure would be at the bottom of “fun“ activities for me. Here is my Puget Sound freighter waves nightmare…… SF

pnwflyfishing.com

New To Me Stream Flow Chart

I normally use the USGS charts but ran across this on another site and thought it was pretty informative. https://snoflo.org/flow Anything else that others are using?

pnwflyfishing.com

In addition to keeping good records on stream conditions on my own outings and how they affect fishing and wading, if friends tell me about a trip, or someone posts trip info here and mentions good/bad fishing or wading conditions on a stream I can identify, I'll factor those into the Too High-High-Medium-Low-Too Low algorithm that creates my graph in the Riverflows.net app.

 

[GeekOfAllTrades]

If you are also looking for more generalized information on how to use CFS flow data to plan trips, I posted some thoughts here...

Basic Survival Skills for a Flyfisherman Just Learning to Swim

I am a shit swimmer. #1 rule is don't panic. Me too. I can swim ok, but swimming itself especially for leisure would be at the bottom of “fun“ activities for me. Here is my Puget Sound freighter waves nightmare…… SF

pnwflyfishing.com

New To Me Stream Flow Chart

I normally use the USGS charts but ran across this on another site and thought it was pretty informative. https://snoflo.org/flow Anything else that others are using?

pnwflyfishing.com

In addition to keeping good records on stream conditions on my own outings and how they affect fishing and wading, if friends tell me about a trip, or someone posts trip info here and mentions good/bad fishing or wading conditions on a stream I can identify, I'll factor those into the Too High-High-Medium-Low-Too Low algorithm that creates my graph in the Riverflows.net app.

Thanks for the tips, much appriciated!