Tuesday, September 16, 2014

Update from the Lake: Tracks and Things...

...on the beach at Butt Valley Reservoir, also seen here and here.
Probably dog.
Sasquatch — I mean, human.
Small crawdad pinchers. Finger is red from blackberries.
Corbicula fluminea or Asian clam, not zebra mussel.
Jelly blob, probably Pectinatella magnifica, a type of freshwater bryozoan.
Enlargement of the same photo. This is a colony, and each of the circular to star-shaped indentations or rosettes supposedly consist of several individual organisms.
Shaly beach sand. Hopefully we'll see the reason for the odd shape of this sand in a few days!

Monday, September 8, 2014

Varying Water Levels at a Few Reservoirs in California

When MOH and I drove to Butt Valley Reservoir a couple weeks ago, we were surprised by the lake low lake level: it looked lower than we remembered seeing it, although we haven't been frequenting the area routinely for several years.
Standing on a wider-than-usual beach near the boat ramp on the east shore, looking south. 
The boat ramp is the dark, shadowed line below the tall trees on the same shore I'm standing on. The dam is a ways around the corner to the southeast behind the tall trees.
This picnic table from the day use area was moved out onto the beach, presumably as a prank. Photo from August 22nd.
A few days later the same picnic table was at water's edge.
Photo from August 26th.
Although the angle of the photo is a bit different, you can see that the lake has risen by looking at the boat ramp and a couple logs in the background, not to mention the trees. In addition, the beach on the far shore is no longer visible.

It isn't really normal for water levels to be rising this year in California reservoirs, but the lake level in Butt Valley Reservoir (the lake is alternately called Butt's Lake, Butt Lake, and Butt Valley Lake) is notoriously variable. In fact, swimmers and boaters are warned to watch the lake level, as it can rise suddenly if water is released from the next lake up the ladder, which is Lake Almanor. Unfortunately, I didn't get a picture of the warning sign.

Indeed, in case I didn't believe my eyes (or you don't believe my photos), Butt Valley Reservoir contained 35,117 acre feet on August 22nd (probably a permalink, or play around with the dates yourself) and 41,627 acre feet on August 26th (same chart). Total storage capacity of the reservoir is 49,800 AF. The chart of reservoir storage for the month of August can be seen here (a probable permalink).

Meanwhile, the lake upstream in the Feather River watershed so-called "Stairway of Power" was dropping (tabular data), especially after August 21st (graph).

We've all seen some of the recent pictures of the main reservoir at the downstream end of the Feather River system (Lake Oroville above Oroville Dam). I wouldn't mind posting some of these here, but surprisingly, CDWR describes these photos as public domain and copyrighted and not for redistribution at the same time (right click on this one, for example). Instead of photos, view the Lake Oroville storage chart for all of 2014 here (should be a permalink).

What we can discover through various CDEC links and calculation tools, is that the May 2014 peak at Lake Oroville of 1,877,682 AF was considerably below the average May peak of 3,042,972 AF. I've read in comments that the 1990, 1991, and 1992 years were worse California drought years than 2014 (perhaps based on statewide storage, rain, runoff, or wishful thinking?), but at Oroville, storage at the beginning of September was a little higher in all three of those years than it was this year: 1,188,782 AF in 1990, 1,392,300 AF in 1991, and 1,401,554 AF in 1992, compared to 1,100,873 AF on 9/1/2014.

Friday, September 5, 2014

Update from the Lake: A Berrying Road Trip

We took off in under fairly clear skies and on a remarkably haze free day — the entire summer has been plagued by haze, smoke, and inordinate amounts of dust — in search of blackberries. On a loop road to the south, we stopped at a little overlook to look back at the lake, across part of a large burn from about two years ago.
Dead trees above the same overlook.
We found our berrying spot...
...right down by the river.
It's hard to tell from this photo exactly how far down the water line is in this reservoir, but it's as low as we had ever seen it, though relatively much higher than the main reservoir downstream (great photos at the link, btw).
A close up of the entangled mass that floated in on the waves...
...from this larger mass out in the lake.
Not sure what this water plant is, but it may not be welcome in our western lakes, as it would seem to impeded boat traffic and swimming.

Monday, September 1, 2014

Early Morning Smoke

The sun is about to rise through thick smoke blanketing the
southern Humboldt Range.
Here, the sun is up, and the smoke is so thick that the high part of the Humboldt Range, which would normally be visible in the distance on the left part of the photo, is completed covered by the smoke layer.
Looking off to the southwest, layers of smoke over a green field. 
A screeching hawk on a phone pole. 
Not sure exactly where this smoke, smoke so thick I could smell it most of the day even when working inside, is coming from, but I'm suspecting the Happy Camp fire complex and others in NW California, at least until I hear anything to suggest otherwise.

Note: Photos uploaded directly from my phone to the Blogger app. Blog post was then manipulated on the phone using the Chrome web interface, which is quite awkward. Final touches added on the laptop.

Monday, August 25, 2014

Rhyolite Porphyry from Majuba Hill III

GSN field trip Day 2: We've taken a few Majuba Hill samples out of the bag.
We'll now take a look at the farthest right sample, having already seen
Rocks #1 & #2 and Rock #3.
One side shows a weathered surface, with dark brown iron oxides and the copper carbonates malachite and azurite.
I suspect that the reason I picked up this rock was because of the mineralized appearance of the outer surfaces. I probably had no idea this rock would turn out to be yet another sample of rhyolite porphyry when I grabbed it off the dump. Scratching the iron oxide reveals it to be goethite mixed with jarosite — according to the old Bear Creek porphyry copper exploration method matching oxide color to a complex triangle of powdered goethite, hematite, and jarosite with mixes in between. The only partial example I can find of this method online can be seen here.
A fresh surface of the same rock.
Zooming in on the fresh surface, we can see that we indeed have yet another sample of rhyolite porphyry: 
Although the former feldspar phenocrysts are nearly completely gone to black tourmaline needles with a scattering of brown iron oxides (goethite + jarosite) and greenish to blue-green copper minerals, the gray, fresh-looking quartz eyes are clearly recognizable.
What's really interesting about this rock is the white to gray matrix.
The matrix of this current hand sample is considerably more altered than that of our previous sample, Rock #3: The matrix is shot through with tiny tourmaline needles and finely disseminated sericite. Additionally, the tourmalinized feldspar sites within this rock contain only minor copper minerals when compared to the feldspar sites of Rock #3. I was a bit surprised at this lesser amount of copper after spying the obvious blues and greens of copper minerals on the weathered surfaces.

And here's another surface of the rock, one showing a moderate amount of reddish brown iron-oxide (hematite + jarosite), a pale bluish green copper mineral (or combo of minerals), and black tourmaline.
The iron oxides are very fine-grained and powdery, and from a few boxworky textures, I'd say that they at least in part replace former sulfides (probably copper sulfides judging by the color of the iron oxides). Quartz phenocrysts are visible in the light olive gray right hand side of the sample (these are easier to see in person with a hand lens than in this photo because of the shadows in the photo).

And that's the last of our rhyolite porphyry samples, at least of those that haven't been brecciated!

Rhyolite Porphyry from Majuba Hill I
Rhyolite Porphyry from Majuba Hill II
Rhyolite Porphyry from Majuba Hill III (this post)