Flood Season Riding in CA

[Collin A]

Brunchers,

Happy "Storm" Season from Sacramento, currently sitting at a lovely 30 ft (average, NAVD88) with the nearby American River potentially cresting at 40 ft if the current forecasts hold. This post may be a bit off-topic, but it is riv/bike related because I have been doing some inspection rounds of the levees on my Appaloosa, much to the confusion of my coworkers and the public I see out there!

Some Background:

Like most of the rivers in California, the American River (and Sacramento that the American feeds) is not a "natural" river and instead dammed at several locations along it's length and constrained for hundreds of miles by levees of varying levels of 'integrity.' The levees tend to contribute to flood risk, somewhat counterintuitively, because they constrain and limit how wide a river can go, thereby making the river run narrower, taller, and faster and causing more flooding if (or rather when) a levee breaks. The dams, specifically the Folsom Dam, serve to capture the more erratic rainfall and stream flows and later release them over a longer period to avoid damaging the levees and flooding the cities downstream. 

Currently, Folsom is releasing about 190,000 gallons a second (or about 1 olympic swimming pool every 3 seconds) in anticipation of the next several storms to make sure there is enough space to capture all of that water (before they have to release that volume gradually to then make space for another big storm). They will likely continue to release more water as the storms continue, and they are currently scheduled to release 40% more starting tomorrow. For a point of reference, the levees are designed to handle at least 4 times that amount, and the dam is designed for another 5 times more!

Bike Stuff:

I managed to get a ride out before this most recent storm and got a few photos of condition of the river paths and river itself. I'll be doing a similar lap early next week when the river rises another 10 feet or so and will likely try to make it a weekly occurrence as long as the storms keep up and I don't get called to an emergency response.

One of the boat ramps underneath Howe Ave, currently under water.

Looking downstream from Watt Ave bridge

Resources for those in the area related to forecasting:

River forecasts: CNRFC - California Nevada River Forecast Center (noaa.gov)

Reservoir Release Schedules: CDEC - LastRes (ca.gov) 

Stay safe out there,

Collin in Floodramento

[Patrick Moore]

Interesting post and photos; thanks. I hope all y'all come out of it all unscathed.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[George Schick]

I used to work for a company that had a data center down there in the Pocket neighborhood, just across the road from the levee.  Never made any sense to me and supposedly they had plans to dynamite the levee further downstream to let flood water out in the event of catastrophic flooding of the Sac River and a breach. That data center has long since been closed.

Also, I have read where numerous "camps" of homeless types are doing some damage to the levee in various places.

Finally, as I understand it from history, the natives (indians) warned soldiers to build their fort further upslope from the river because of annual flooding, which they did.  Early settlers, however, did not, which led to some horrific flooding of the Sacramento area in the 19th Century.

[Wesley]

Its true about the consternation from the public! I was out a few nights ago to see what conditions looked like on the American River, and at an intersection some car pulled up next to me, pointed a camera at me and started in with a bunch of questions about why I was out riding in the rain. It's a bike thing, you wouldn't understand.

-Wes

[Wesley]

Oh, and further to Collin's point about the flood risk from channelizing the river: the Sacramento River is expected to overtop the Fremont weir starting tomorrow for the first time since 2019, which was before I moved to town. This causes the river to flow into the Yolo bypass rather than flooding the city. Interstate 80 crosses the bypass on a causeway and I've heard descriptions of the 2017 flow through there that sound apocalyptic. Nothing in the forecast indicates that we will see even a third of that flow, but it is going to get wetter and wetter over the next few weeks, so who knows?

Bike content: a week ago I rode out into the bypass on some gravel roads - it was so refreshing to find a local ride that doesn't involve cars! Looks like that'll be impossible for a little while.

-Wes

[Jeremy Till]

I've lived in Sacramento for most of the past 13 years and have lived through a few of these flood seasons and the drought years in between. The flood years always feel like welcome relief from the drought but also drive home just how reliant we are on the levees and infrastructure like the weirs and the Yolo Bypass to prevent floods. Impressive when it's working, but scary when it fails, as it did in the south part of the county last weekend. 

Flood control infrastructure is also of particular interest for the cyclists in the region because the levees also end up providing some of the best places to ride in the region. Some are topped with relatively quiet country roads with good views, being elevated over the surrounding areas. Others have gravel roads/paths that are off limits to motor vehicles, providing a great place to get your recommended dosage of vitamin G. The American River bike trail, the our region's most widely used and well known bike infrastructure, lies completely within the limits of the levees that control that river. Most of my recreational rides spend at least some time on or around a levee, and when they are closed for maintenance and upgrading some of my favorite routes are off-limits.

Here are some pictures (with bike content) of one of the weirs and the Yolo Bypass after they flooded it during the 2017 winter season, taken on a ride out there with some friends. This is not the Fremont Weir but the Sacramento Weir, which is further downstream, just north of West Sacramento. The big concern that year was the failure of the spillway on the Oroville Dam (upstream on the Sacramento) and the potential impacts to the region if the dam itself were to fail, which luckily it never did: 

https://flic.kr/s/aHskNRXT2L

From the year before, the flooded Yolo Bypass from the I-80 causeway (which also has a bike lane). I work in Davis and commute across the causeway most days, so have always tracked the water levels in the bypass with interest: 

https://flic.kr/p/EQeANj

-Jeremy Till

Sacramento (obvs), CA

[Eric Norris]

Download full resolution images

Available until Feb 5, 2023

I headed out to Folsom and Nimbus dams this morning to see the water being released into the American River. Hauled my medium format camera out and got a few shots.

Quite a sight, although the use of the new spillway at Folsom Dam makes for slightly less dramatic photos. As has been noted in this thread, they’re releasing water from Folsom Lake to have enough capacity to hold the runoff from the next big storm.

--Eric Norris
campyo...@me.com
Insta: @CampyOnlyGuy
YouTube: YouTube.com/CampyOnlyGuy 

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[Mike Godwin]

Jeremey, Eric, et al

Get some photos of the rack line in between flood/release events to gauge river heights. A fun hydrologic exercise while riding. Rack line? The topmost line of organic and anthropogenic debris parallel to flow deposited on river bank/levee. Lower flood levels will result in lower parallel rack lines, and of course, a higher flood event will wash away all and reset the picture. Kind of like lateral moraines, but quicker elapsed time.   Or put sticks at the shoreline as a snapshot in time of the water level, and see how the water level changes over time.

Man-o-man, the Oroville dam emergency several years ago, that was scary sh^t!

Mike "observing rack lines on Prefumo Ck and Laguna Lake" Godwin SLO CA

[reynoldslugs]

The Russian River is flowing pretty high here in Sonoma County.  Weather report is for more rain for the next few weeks.  My winter rain bike is a Bruce Gordon with Sim Works fenders, and it’s getting plenty of use.  Pictures to follow.  

The national news outlets are covering the storms and flooding here, with a lot of reports from the sites of my favorite rides - along the Russian River, Guerneville, Monte Rio, Coleman Valley, Bodega Bay, Jenner.  

The flip side of all this rain and potential flooding is that we are still in drought.  Another one of my favorite rides is from Healdsburg to Lake Sonoma, up Rock Pile Road.  Lake Sonoma has been shockingly low for the last few years, and we really, really need the rain.  I just hope the flooding doesn’t do too much damage to folks in the low lying areas.

I’ll ride close to home today, steel bike + fat tires + cantilevers + good fenders, with screaming hi-viz rain gear thrown in for good measure.

And yes, everyone please stay safe.

Max Beach

Santa Rosa CA

On Friday, January 6, 2023 at 4:36:51 PM UTC-8 Collin A wrote:

[Jim Bronson]

The Sacramento-San Joaquin delta is just trying to return itself to its natural state, that's all.

Nearly 40 million humans and the engineers employed by their leaders prevent it from doing so, to the detriment of the natural environment.

Why don't we, as a species, just farm in places where it actually rains, as opposed to the Central Valley of California?

Maybe then there'd be enough water for all the city dwellers in LA and SF.  But what do I know.

Jim

Austin suburbs, TX

Oregon native, child of 2 California bay area natives.

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[Rick Thompson]

We live in Fairfield and have friends who moved to the pocket area. There is a standing arrangement that we can evacuate to their house in case of fire and they can come to ours in case of flood. In the last few years we are at Fire = 2 and Flood = 0, but we are keeping the guest room ready this week.....

[Mike Godwin]

Jim

Don't forget that the impact by hydraulic mining in the 1860s-1875 or so, irreparably modified the American-Sacramento Rivers' inland delta by raising the streambed something like 15 feet, I've read. I think the 1862 flood may have been slightly influenced by the hydromodification, however, no human settlement can withstand 30+ days of atmospheric rivers. Of course, by that time, the lower San Joaquin, Kings, Kern, Tule, Kaweah Rivers (Tule-San Joaquine basin) had nascent beginnings of modifications. The northern San Juaquin basin and Sac/American Rivs were certainly modified by then. (Say, anyone have historic meteorological data from 1861-1862, how do ocean temps compare with what is happening now?)  

So much of the last 100 or so years, the flood stage is predicated on the man-made stream profile, in addition to engineering "improvements."  I suspect the river levees were constructed from the transported sediment from hydraulic mining, thus bringing the stream bed to pre-mining or deeper elevations. But then the levees constrained the bank width with later ramifications.  (When were the river flood stage weirs and bypasses constructed?)  During a related project in my consulting years, this paper came out highlighting the DoE accomplishments of cascading solutions needed to correct compounding problems. Closing_the_Circle_Report.pdf (energy.gov) I see regional hydraulic modifications as similar large-scale challenges but less serious than radioactive waste. Rad waste is acute environmental health impacts, vs the delta and all of California's surface water plumbing are subject to multiple chronic risks.  

All yuze Sacramento Delta ibobs stay safe and on high ground this next week.  NOAA forecasts look pretty grim, at least here on the central coast. 4-5 inches of rain in the next 2-3 days. 

Mike SLO CA