2019 River/Stream Crossing Reports

[ERIC]

This being a big Water Year, we'd appreciate any and all reports (with photos if you have them) of river and stream crossing conditions in the Sierra. For new members and followers of this site, I highly recommend skimming this thread which gives good advice from another big snow year we had.

[SSSdave]

http://cdec.water.ca.gov/reportapp/java ... FNF.201902

Have been looking at this CDEC full natural flow ( FNF ) page (link above) for years. Although flows are measured at lower elevations, it can relatively be useful for understanding what has been occurring at higher elevations. It can also be useful for timing trips to say Yosemite Valley or when waterfalls are at their peak flows. Our two most impressive roadside whitewater rivers at snow melt peak are the Merced River along SR140 between El Portal and the Kings River along SR180 between Horseshoe Bend and the Kings Canyon National park boundary, especially near Boyden Cave.

At this time of year after winter fronts have waned, the primary factor changing daily water flows is temperatures. Thus after hot spells flows increase significantly. It also reflects the comparative size of our major rivers at different times of the year. By late summer, our Sierra rivers with highest flows also tend to be those with the highest Sierra Nevada elevations where snow lasts longest or in the north where volcanic geology is slower to release water than granite geology to the south.

At right top one can select an earlier month to see how different these river levels can be. Selecting a winter month when we had a number of large storms shows dramatic changes. The current May 7 highest FNF is on the Feather River with about 16948 acre feet gauged on that day while in the southern Sierra, the Tuolumne, San Joaquin, and Kings Rivers are all a bit less than 11k. During a big storm on February 14 the Feather that has much more elevations below the snow line, recorded 60k while it recorded just 17k on Feb 13 and then 34k Feb 15. During the same storm, the San Joaquin where most precipitation falls as snow that does not run off, it shows 3.9k on Feb 13 15.8k Feb 14 and 10k on Feb 15.

[paul]

While I did not have to cross it, here are a couple photos of the North Fork of the Kings between Portal Lake and Big Maxson Meadow. A lot of snow in this area still - like 5-6 feet next to the river. I will use this to illustrate a point for those who may be out early and are crossing streams on snow bridges. It's not always obvious where the flow is going under the snow. At one point I got into position to take a photo, then went further along the bank, only to realize that I was on an island and where I had been standing to take my photo was actually right on a snowbridge. Fortunately a stable one, 5 feet or so thick. But I might not have been as lucky. In general, when you look at teh course of a stream that is covered by snow, you can identify the path of the stream, and you can see high and low points along that path, which are almost always thick and thin points in the snow cover, respectively. so always cross at the high points. I am mostly doing this on skis, which has a big advantage, as my weight is spread out over a much larger area than if I was on foot, plus in most cases I can get up a bit of speed and glide across a doubtful spot. On foot, that does not work. Having a ski or trekking pole is a big help, as you can reach out ahead and poke-test a questionable spot. Be careful out there. If in doubt, find a better spot. And if at all possible, aim to cross early in the morning when things are still crusty from the overnight freeze.

IMG_1110r.jpg

IMG_1109r.jpg

IMG_1108r.jpg

IMG_1106r.jpg

[kpeter]

Frog Creek crossing on the way to Laurel Lake: June 6 lower crossing impassable. One report was that a hiker made it across the upper crossing at waist deep, but on June 9 experienced packers report turning back.

DSC03836.jpg

Outlet bridge at Vernon Lake:
On June 7 water around both ends of the bridge and crossing necessitate crotch deep wading upstream to reach the bridge. Most turned back.

DSC03883.jpg

HOWEVER by June 9 water had receded more than one foot, water was much more placid and most everyone was wading knee deep. Whether this was a result of the weather or marks the high water mark I am not sure.

DSC03950.jpg

[maverick]

https://andrewskurka.com/psa-hazardous- ... LdAz19C3NI

[SSSdave]

Notice how June day to day flows are dependent on temperatures.

FNFb_61319.jpg

FNFa_61319.jpg

[MichaelRPetrick]

Streamflow question, hopefully this is the correct place to ask it (will delete and make a thread if need be):

Why the heck does the common wisdom about "cross streams in the morning so water is low" seem to be incorrect in so many places in the Sierra?

I am intently watching the Hetch Hetchy intake gauge to have a general idea about whether flooding on the Tuolumne will have subsided enough to do the GCOT over July 4th.

The Hetch Hetchy intake gauge consistently bottoms out late in the afternoon.

Don't take my word for it! This is a live screencap of the gauge's height - most recent reading 3:30:

Capture.PNG

[AlmostThere]

Does it matter on the GCOT when you know that even at the lowest point, the river is still uncrossable without that bridge in Pate? The lowest flow of the river right now will not be as low as the river in August or September... and that does not even account for Return and Register Creeks, which are flowing into it and you have to cross.

The other question in my mind -- if the melt happening up high, on the creeks, is happening in the afternoon and slowing down in the evening and overnight, is this pattern really an indication of how long that melt takes to travel down the creeks into the river and then to wherever that gauge is measuring the flow?

[Wandering Daisy]

There is a long lag time from the high up melt down to Hetch Hetchy. And if it is freezing at night, the melt water does not get peaking until late afternoon. It is the same when I was walking on the snow those same dates up at Lunch Meadow on Summit Creek. The snow did not get wet-sloppy until well after noon. So by 2-3 PM down at Hetch Hetchy, the major amount of the day's melt had not yet made it down the canyon. If you instead were considering crossing near the melting snowpack, the low would be closer to 8-9 AM. There is also a time lag from when the sun rises and when the snow starts to thaw.

The bridge at Pate Valley is not safe to cross in any flow. The bridge has been severely damaged since last year, many planks missing. It is now more like walking a log. There is also a landslide over the trail a mile or so above the bridge. I do not know if anyone has checked the bridge over Return Creek. It washed out in the late 1990's and was rebuilt. Here is how we crossed Register Creek in 2003.

101_0163.JPG

[MichaelRPetrick]

I should clarify: I'm not asking about this for GCOT at all, ignore that particular trip. I've a good idea of what to expect and am ready to turn back. Am curious about general stream crossing/melt dynamics here:

I just always read "Be sure to cross dangerous streams earlier in the morning." But every Sierra gauge I've looked at bottoms out late in the day and peaks at midnightish or earlty morning:

San Joaquin near Reds Meadow:

Marble Fork of the Kaweah:

Happy Isles:



Of the above three, only Marble Fork displays something close to the expected flow pattern.

The "delay in melt flowing/making it to lower elevation gage sites" is obviously correct, but I wonder if the usual "cross late in the day" needs a strong proviso about elevation, given that the lower a crossing is, the bigger a catchment basin it's likely pulling melt from, and the more flow there's going to be. The higher a crossing, the smaller it's probably going to be, and while the "late-day-melt" pattern will be true, it'll be at a smaller crossing...

Put as a question: is it the case that heaviest and possibly most dangerous crossings will be the most deviant from the expected "late-day melt" pattern?

EDIT:
-------------------------
Argh, am screwing up the attachments, sorry! Will fix this evening.