American Flows - 8000 cfs?

[Renty]

Was planning on heading out Friday after varied success over the last few weeks. Latest water forum post shows the flows dropping from 2000 to 1250, but the current gauge shows 8000 today. 1398513986What’s up with the flows!?!?! Any ideas on how long this is going to last?

[JasonB]

Take a look at what’s coming into Folsom right now and factor in that we are expecting a lot more warm rain still. It’s precautionary to keep Folsom from getting too much higher until there is a better sense of how much runoff they will be contending with. Probably won’t stay that high for long? Friday will almost certainly still be high. It’s a mixed blessing, as this wouldn’t have been an issue a month ago but we are currently facing more substantial runoff...which is ultimately a positive. Not so great for now though.
JB

[TahoeJoe]

Here's the noaa prediction for flows. Friday is predicted to be the peak, even higher than today.

https://www.cnrfc.noaa.gov/graphicalRVF.php?id=SAMC1

[Morgan]

Ya it's been pissing rain for at least the last 24 hours up here. Melting snow like crazy!

[Bill Kiene semi-retired]

Lower American River going up a lot on 3/21/2018

Project: Nimbus Dam

Please make the following release change to the American River.

date time from (cfs) to (cfs)

3-21-18 0800 1750 3000
3-21-18 0900 3000 4000
3-21-18 1000 4000 5500
3-21-18 1100 5500 7500

Comment: Imminent flood control, preparing for storm inflows later this week.

Issued by: P, Manza

[STEELIES/26c3]

Folsom Lake has now risen 26% of its total capacity in less than 2 weeks. it went from 523,000 AF to 780,000 AF. We will still fall short of needed snow pack but at least our reservoirs will all be full until summer and the higher water content of the snow we do have will see us through...

[JasonB]

Well it looks like we’ve got another big event on the way, I’m betting the flows are about to double for a few days at least. Lots of warm rain on the way supposedly

[Jeff C.]

10K this morning.

[STEELIES/26c3]

10K this morning.

I would bet 15,000-20,000 by next week

[Troutsource]

I hope with the new overflow spillway in place they don't need so spill as much prematurely and preserve a higher pool level -- maybe leading to lower temps in the summer outflow -- maybe allowing more summertime trout.

Does anyone know if they've already altered their calculations to reflect the new spillway?

[Jeff C.]

I think they are still using the old maximum storage regime established over 30 years ago. Even with the new spillway, I understand that it takes years to establish a new regime. We probably will be seeing further increases in flow over the weekend depending on what the inflow into Folsom is.

[JasonB]

I hope with the new overflow spillway in place they don't need so spill as much prematurely and preserve a higher pool level -- maybe leading to lower temps in the summer outflow -- maybe allowing more summertime trout.

Does anyone know if they've already altered their calculations to reflect the new spillway?

Nothing “premature” about releasing 20,000cfs (or maybe more?) if the lake is nearly full and projected inflows are looking to hit 80,000-90,000cfs.
There is of course more snowmelt yet to come, even though it might not be particularly substantial compared to other years it is still a lot of water to plan for. Those flow projections are just that of course; it is quite possible that the actual inflow might only go up to 40,000cfs? Thing is, if we do get a big “pineapple express” rain up on the passes they will have no choice but to ramp up the dam release substantially. Spillway or not. https://www.cnrfc.noaa.gov/mobile/riverImage.php?id=CBAC1&type=Fcst

[STEELIES/26c3]

ABSOLUTELY...
It's been a long time since we had 82% capacity in April before even a hint of the first summer thaw...
Don't expect typical flows on any of our valley rivers for months...

[hwchubb]

I believe that the maximum levels at different times in the spring are a federal mandate, so I’m not sure that the spillway would change that at all without some legislative action, so I wouldn’t hold my breath. I don’t know that for sure, maybe those of you closer to that than I am know a bit more?

[Morgan]

ABSOLUTELY...
It's been a long time since we had 82% capacity in April before even a hint of the first summer thaw...
Don't expect typical flows on any of our valley rivers for months...

We have had a thaw for the last few weeks. The last few days we have had very high night time temps. No where near freezing. And with all the rain the last couple weeks its melting more than you may think. Today they were calling for rain up to 11k feet. The snow is melting at a rapid rate. Id imagine the flows for the American will continue to rise the next couple days.

[tascaso]

Yep, the Merced at Happy Isles, Yosemite went from 800cfs to 8000cfs, the park is closed. Now thats a blow out. Guess I will head to the surf in the morning and hunt for stripers.

[STEELIES/26c3]

Yep, the Merced at Happy Isles, Yosemite went from 800cfs to 8000cfs, the park is closed. Now thats a blow out. Guess I will head to the surf in the morning and hunt for stripers.

Plot of Reservoir, Scheduled Release

Date / Time REL SCH
2018-04-16 01:00 6400.0 CFS
2018-04-15 23:00 6700.0 CFS
2018-04-15 21:00 7000.0 CFS
2018-04-15 01:00 7300.0 CFS
2018-04-14 23:00 7600.0 CFS
2018-04-14 21:00 7950.0 CFS
2018-04-14 01:00 8300.0 CFS
2018-04-13 23:00 8700.0 CFS
2018-04-13 21:00 9100.0 CFS
2018-04-13 01:00 9500.0 CFS
2018-04-12 23:00 10000.0 CFS
2018-04-12 21:00 10500.0 CFS
2018-04-12 01:00 11000.0 CFS
2018-04-11 23:00 11600.0 CFS
2018-04-11 21:00 12300.0 CFS
2018-04-11 01:00 13000.0 CFS
2018-04-10 23:00 14000.0 CFS
2018-04-10 21:00 15000.0 CFS
2018-04-10 01:00 16000.0 CFS
2018-04-09 23:00 17300.0 CFS
2018-04-09 21:00 18650.0 CFS
2018-04-09 00:00 20000.0 CFS
2018-04-06 09:00 25000.0 CFS
2018-04-06 08:00 22500.0 CFS
2018-04-05 14:00 20000.0 CFS
2018-04-05 13:00 17500.0 CFS
2018-04-05 11:00 15000.0 CFS
2018-04-05 10:00 12500.0 CFS
2018-04-04 09:00 10000.0 CFS
2018-04-04 08:00 9300.0 CFS