Fan of Columnar Jointing? Here's a Real Gem for You in the Sierra Nevada, and it's Not Devil's Postpile

Tucked away in a small corner of an unheralded canyon of the Sierra Nevada is a real gem of a geological locality. It is a marvelous example of columnar jointing that has been modified by glacial scouring, and it's NOT called Devil's Postpile. Welcome to the Columns of the Giants.

The Stanislaus River doesn't quite have the panache of the Merced River, which flows through Yosemite Valley, or the Tuolumne River, the architect of Hetch Hetchy Valley. It's not protected as a national park like Kings Canyon. It had glaciers during the ice ages, but they didn't have the volumes of ice necessary to carve stunningly deep gorges like the previously mentioned river valleys. But it does have a grandeur all its own.

The headwaters of the Stanislaus expose rocks that are quite distinct from those of the other more famous rivers. The rocks have a darker aspect, due to being composed of relatively young volcanic rocks, rather than the granite that makes up three-quarters of the Sierra Nevada. Highway 108 crosses one of the uppermost tributaries at Sonora Pass (9,624 feet/2,933 meters), and travelers can get a spectacular view of these former volcanoes that were active about 10 million years ago. They erupted onto a muted landscape of eroded granitic rocks. Some of the eruptions produced flows that traveled more than fifty miles downstream through the canyons of the Ancestral Stanislaus River. Later erosion acting on these flows produced the famous Stanislaus Table Mountain in the vicinity of the Gold Rush Towns of Jamestown and Sonora.

Beginning around 2 million years ago, glaciers began tearing away at the higher parts of the Sierra Nevada, removing many of the volcanic flows and carving U-shaped gorges like the one above, visible just a few miles downstream of Sonora Pass at Chipmunk Flat. The ice age was not a single event. The ice advanced and retreated more than a dozen times, with warmer periods in between that lasted for thousands of years. It was during one of these interglacial periods that something extraordinary happened in the upper reaches of the Stanislaus River drainage. Roughly 150,000 years ago there was a volcanic eruption down in the canyon.

It wasn't a large eruption, certainly not on the scale of some of the rhyolite cataclysms that devastated the regions east of the Sierra crest 767,000 years ago. It was more of a mild cinder cone eruption that might have flooded a portion of the canyon, flowing just a few miles downstream before the lava flows ceased. Subsequent glaciations scoured away much of the remaining lavas, and river erosion removed still more. Hidden in a cleft, a basalt dike just upstream of the columns may be all that remains of the volcano responsible for the eruption. It's not much, just the fracture in the granite that filled with basalt that fed the eruptions above. 

The remains of the lava flow, though? Spectacular! The lava flow (or flows; there were possibly two of them) was ponded by some obstruction downstream, most likely a glacial moraine, and a modest lava lake developed, several tens of meters deep. As the lava cooled, it shrank and the rock fractured in generally hexagonal columns roughly perpendicular to the surface against which the lava flowed. Since the lava flows were erupted onto a canyon bottom with slopes on either side, not all of the columns are vertical (this is also true of the better-known Devil's Postpile). 

Subsequent glaciations (primarily the Tahoe and Tioga stages for those who want to know) tore away at the lava flow, exposing the columns. Over the last 10,000 years or so since the last Tioga glaciers melted away, frost wedging has pried many of the columns loose, dumping them into a vast talus slope that covers the base of the lava flow. Cold air emanating from the base of the talus suggests that a mass of ice might actually remain deep within the rockpile. 

Columns of the Giants can be easily visited by following Highway 108 about 25 miles east of the Pinecrest Lake Resort area or 13 miles west of Sonora Pass. Overnight accommodations can be found at nearby Kennedy Meadows and a number of National Forest campgrounds. Educational groups may be able to make arrangements to stay the High Sierra Institute at Baker Station just a few miles away (contact the Yosemite Community College District for more information).

Stanislaus National Forest has provided a parking area and simple toilets for visitors, and a paved ADA-compliant trail and bridge provides access. The trail is only a few hundred yards long, and the visual rewards are great. 

Can't get there in person? My friend and colleague Ryan Hollister put together a marvelous virtual field exercise that provides an experience that is the next best thing to being there. It was featured on NPR's Science Friday a few years ago.

A Day on the California Prairie: Finding the Precious Places Near Home

Yosemite National Park is closed. The coastline is closed. The state parks are closed. Am I complaining? Not in the least. We are facing an unprecedented threat, so we must curtail our freedoms a bit until the scientists and the doctors (and all of their heroic support staff from nurses to foodworkers to custodians) can do their work protecting us. And we must continue to do our part, isolating ourselves from each other, and from the virus itself. I pray that you are able to stay healthy and safe, and if tragedy strikes, that you find peace in some way.

In the meantime, there are a few legal ways to maintain sanity. Exercising in isolation from others near home is one way. If the city parks are crowded, find a deserted road on the edge of town to walk along. It is a way that we can find the precious and undiscovered treasures that have always been just outside our towns. As it turns out, some treasures are ephemeral, lasting only a few weeks.

My town lies on the edge on one of the few remaining largely untouched prairies left in California. These prairies used to extend across the entire Great Valley, but agricultural development has displaced 95% of the grasslands. There are a series of wildlife refuges up and down the valley that protect some of the remaining wildlands or rehabilitated farmlands. The rest of the prairie tends to be found on the margins, in the foothills of the surrounding mountains where the soils are too thin to support agricultural development.

The rainfall this year has been perilously low, with not a drop in the entire month of February. But March and April saw a resurgence in precipitation and the drying sprouts reawakened, and flowers have appeared in abundance throughout the Sierra Nevada foothills.

We took a drive through the prairie that remains between the Tuolumne and Stanislaus Rivers, and were treated with an explosion of color. I'd love to say I was an expert botanist and tell you all the species, but beyond lupines and poppies, my knowledge of flowers is sadly lacking. What I enjoyed today was the profusion of color.

We are living in one of the most challenging times many of us will ever experience short of all-out war. Natural disasters horribly affect particular regions, but there is always help from elsewhere, and there are places of retreat and refuge if an earthquake or hurricane strikes. But this one is a worldwide viral attack, and all we can do is shelter in place until it passes. It's scary, it's dangerous, and many are suffering. I hope there are a few moments of peace and serenity to be found here in these little treasures close to home.

A Journey of Ten Million Years...the Salmon of the Sierra Nevada

Chinook Salmon attempting to enter the fish ladder at Camanche Dam on the Mokelumne River

They've been coming here for at least ten million years. Every year, without fail. The lands changed, but still they came. If one waterway was blocked, they eventually found another. Sometimes they were isolated, and could never return to the sea, but they survived anyway. They are the salmon and trout of the Sierra Nevada.

Stanislaus River at Knight's Ferry

Anadromous fish are those that live much of their lives in the oceans, but which return to freshwater streams to reproduce. One might wonder why they would have such a complicated breeding scheme. In all likelihood, it had to do with the survival of the young fish. Rivers and streams tend to offer more hiding places than open ocean, and the young have a chance to grow large enough to survive. The most familiar of these fish are the various species of salmon and Steelhead Trout. I had several opportunities to view the November migration of the Chinook Salmon this week on three different rivers: the Mokelumne, the Tuolumne, and the Stanislaus.

In historical times, the fish ranged far into the interior of the Sierra Nevada and Cascades Range, being stopped only by cascades and waterfalls too high for them to jump. They numbered in the millions. As European and American colonizers replaced the Native Americans across the state, the fish began a steep decline.

One of the first and worst events was the Gold Rush of 1848. Miners tore up miles and miles of river gravels and disrupted the flow of the rivers with their placer mines (sluices, long-toms, and cradles). Hydraulic mines (water cannons) ripped away billions of cubic yards of gravels from the hillsides and choked riverbeds with egg-smothering silt and clay. Vast amounts of water were diverted from river headwaters to feed the hydraulic mines through a system of flumes and pipelines.

Somehow the fish survived this onslaught, but then something more insidious happened. The dam-makers arrived in the late 1800s and early 1900s to build reservoirs to divert water for irrigation purposes. The dams themselves were barriers to the upstream movement of the fish, but even worse was that water diversions left the rivers to small and warm for their survival. The mega-dams were constructed in the 1960s and 1970s, diverting even more water. One river, the San Joaquin, ceased to flow most years over a stretch of about sixty miles. By the time the last dam was built, more than 95% of the historical breeding grounds for the fish had been made inaccessible to their migration (see the map below).

The blue portions of the rivers have salmon. The historical range is shown in black. Source: https://noaa.maps.arcgis.com/apps/MapJournal/index.html?appid=ceebefd9685143daa5bf30d5a7e0c7fa

Millions of years ago, this landscape was much different. The Sierra Crest was lower than it is today, but the summit region was covered by volcanic complexes not unlike the Lassen Peak complex and other parts of the Cascades. Periodic eruptions sent steaming lahars (volcanic mudflows) down the river canyons and onto the floor of the Great Valley (which may have actually been a shallow sea in this area). The rocks from this time period, 5 to 12 million years ago, are called the Mehrten Formation and they can be found throughout the Mother Lode foothills.

The Mehrten Formation has yielded up a treasure trove of fossil species. At Turlock Lake fossils were found of Giant Tortoises and Oncorhynchus rastrosus, the Spike-toothed Salmon. These remarkable salmon were as long as eight feet. They apparently used their "tusks" to fight for territory. Otherwise their lives were similar to the salmon of today. The riverbanks were populated by horses, camels, bison, antelope, giant ground sloths, mastodons, and carnivores, including the ancestors of the bears and wolves. The woodlands were dominated by sycamore and oak. For an excellent overview of the fossil record, check out the technical article by Sankey, Biewer and others, or read their excellent book The Giant Spike-Toothed Salmon and Other Extinct Wildlife of Central California.

Oncorhynchus rastrosus, the Giant Spike-toothed Salmon. Artist: Jake Biewer

Erosional processes steal nutrients from the land and carry them to the sea. It has been remarked that salmon and other anadromous fish return the gift. After they fight their way up the streams and rivers, and after they lay and fertilize their eggs, the fish die. Their bodies provide food for a host of carnivores and scavengers. Long before I found any fish in the Mokelumne River the other day I sensed the lurking presence of several dozen Turkey Vultures. I wasn't actually thinking about fish at that moment, but wondered why so many vultures were hanging around the river.

Moments later the reason was clear, as many were already feasting on the dead fish. The alert eyes that followed the movement of the fish are of an ancient lineage as well. Turkey Vultures are the most common of the avian scavengers, but their ancestors and Condor relatives patrolled these rivers millions of years ago.

These fish have survived for at least ten million years, and it has taken only a century and a half to threaten their very existence. Even now intense controversy follows the negotiations over how much water to devote to agriculture and how much to preserve the future of the salmon and the entire ecosystem that they inhabit. It's not a fish versus people proposition as some have portrayed it. It is a larger question of whether we want to preserve healthy river habitats for clean water, a diverse ecosystem, and for our own recreation and inspiration. Agricultural interests in the drainage of the San Joaquin showed in the 1940s that they were more than willing to destroy a river to apportion every drop of water. Things began to change in the 2000s as agreements were reached to restore flows to the lower river and bring back viable populations of Chinook Salmon. I hope we can be as wise in the other water conflicts around the San Joaquin Valley.

These videos are from the Mokelumne River below Camanche Reservoir, the end of the road for the Chinook Salmon. I had never visited the area before, so I was exploring the trails at the day use area below the fish hatchery. There were lots of fish in the river, and large numbers of them were struggling to break through the gates of the fish ladder, which was closed. I followed the fish ladder into the hatchery grounds, wondering if it actually provided access to the reservoir, but it didn't. It led to holding ponds that were already full of salmon. When the fish are ready, the eggs are harvested and fertilized, providing the stock for the hatchery. The young fish are later released into the river at the hatchery and other locations downstream.



These hatcheries are one way of dealing with the devastating loss of habitat for the salmon, but it seems it would be better if we could provide access to their ancestral breeding grounds upstream. I don't claim any expertise in these matters, but there have to be better answers than what we see happening today. They've been here for at least ten million years, and deserve a chance to be around for a few more.

Liveblogging the Deluge: Perspectives on the Biggest Storm in a Decade, Part Five

We finally got a taste of some of the kinds of squalls that are leading to flooding across much of Northern California. Luckily it was brief, and we have not had problems in our immediate vicinity. The view in the video above is out our front door a few moments after I got home from work, driving in conditions that were much the same as what you can see here.

Radar signal of the storm in the video above, courtesy of  Ryan Hollister @phaneritic

My dear friends who live in hurricane-prone regions are welcome to snicker a bit at my sense of awe at the violence coming from the sky. I live in a dry region, and downpours like this are pretty rare. We got 1.67 inches today, and only six days have had a higher total in the 26 years I've been measuring precipitation in my back yard. That brings our four day storm total to 3.35 inches. Again, that can hardly compare to some of the high numbers coming from the coastal mountains or the Sierra Nevada, but it represents about a quarter of an entire year's rain total in an average year in my village (just over 13 inches in the years I've been measuring).

National Park Service Photo

Meanwhile, the big flood danger in Yosemite has passed as the storm surge topped out at 12.7 feet and subsided a few hours later. Yosemite is in the process of reopening the valley floor to tourism. Highway 140 on the Merced River was closed by mud and rockslides (good pictures at the link). Snow has been falling in the valley and the adjacent high country, which is a good development. We need to build the snowpack to have any hope of putting a dent in the drought.

Dry Creek at around 1,000 cfs yesterday. We'll see how it looks tomorrow at peak runoff. 7,000 cfs is expected.

The Tuolumne River continues to cause some headaches as dam operators try to tread a delicate path between high flows from Don Pedro Reservoir and high flows along Dry Creek, an unconstrained waterway that has been flowing at more than a thousand cubic feet per second for several days. The creek has my undivided attention right now, as flows are expected to crest at more than 7,000 cubic feet per second tomorrow. I hope to get out and snap some pictures.

I have had little to say about the Stanislaus River. New Melones Reservoir is huge, and the Stanislaus is a relatively small river compared to the Tuolumne. As a consequence, the water level in the reservoir has been low throughout the drought. It began this week at 27% of capacity, about 47% of normal for this time of year. The lake has risen about 20 feet this week, and now stands at 31% of capacity (54% of normal).

It's been an interesting week...

Liveblogging the Deluge: Perspectives on the Biggest Flood in a Decade, Part Three

Pictures are emerging from Yosemite Valley! See the update below.

NPS Webcam Photo from Happy Isles at upper end of Yosemite Valley

The flood on the Merced River in Yosemite Valley has crested at 12.7 feet (10,488 cubic feet per second). The highest flow was recorded at 4AM, and the waters are beginning to recede. There are more storms to come in the next few days, but they will be colder, and will start producing snow instead of rain. Although there has been some damage around the valley floor, this has to be seen as one of the best possible outcomes for Yosemite, given the power of this particular atmospheric river storm, and the level of flooding seen elsewhere in Northern California. It is still dangerous out there.

Meanwhile, on the Tuolumne River, releases have begun again from Don Pedro Reservoir, ramping up from almost nothing to 5,320 cubic feet per second. The operators are trying to modulate flows from Don Pedro with the unconstrained flows from Dry Creek to prevent flooding in the low-lying areas of Modesto downstream from the confluence of the two waterways. Flooding commences at about 9,000 cfs in that area. Inflows at Don Pedro are around 15,000 cfs right now (*see the new update below); if the dam didn't exist, the river in Modesto would be approaching 20,000 cfs.

There is a lot going on with the flooding around Northern California, and Southern California is finally getting some precipitation as well. I've been concentrating on the activity on the Merced, Tuolumne, and Stanislaus River drainage basins. Updates will follow as conditions warrant.

UPDATE (1/9/17 11:20AM): The LA Times has a pretty good roundup of flood news from around the state:  http://www.latimes.com/local/lanow/la-me-ln-sierra-storm-20170108-story.html.

UPDATE (1/9/17 11:30AM): The inflow to Don Pedro Reservoir actually reached nearly 38,000 cubic feet per second  yesterday! Water level in the dam jumped 7 feet to 796 feet, for a total of 10 feet since the storm began. The lake gained just over 100,000 acre-feet, to 1,620,000 acre-feet. The lake would overflow at 830 feet, or just over 2 million acre-feet.

UPDATE (1/9/17 12:50PM): Yosemite National Park has posted some photos of flood related effects in the Yosemite Valley area. Here are a few of them...

NPS photo

NPS Photo

NPS photo

UPDATE (1/9/17 7:30PM): At about 3PM, the Merced River receded below flood stage in Yosemite Valley. It's a relief that the flood wasn't worse, especially given greater runoff to the north where there have been some really serious problems during the day. Another storm is moving in, but it's colder and will be mostly snow, which is a very good thing.

UPDATE (1/9/17 9:00PM): As of this evening, Don Pedro Reservoir has surpassed the 800 foot elevation, gaining 5 feet to 801.84 feet, for a gain of another 50,000 acre-feet to 1,690,000 acre-feet. That's about 83% of capacity.

Liveblogging the Deluge: Perspectives on the Biggest Flood in a Decade, Part Two

Check back for updates at the end of this blog...

First off, let me emphasize that I am writing almost exclusively about the central Sierra Nevada and adjacent Great Valley, particularly the drainage of the Merced, Tuolumne, and Stanislaus Rivers. I say this because some very serious things are happening farther to the north, and flooding is occurring in a number of places. If you live in those areas, you need very much to be listening to emergency response officials, and not reading random blogs!

Screen capture of Yosemite Falls from video on NPS Facebook Page

That being said, it looks like we have good news emerging from the storm. Although the rain has been heavy at times, it did not reach the apocalyptic levels that seemed possible earlier in the week. The Merced River in Yosemite Valley is certainly rising towards, and will exceed, flood stage (below), but not nearly to the extent that had been predicted in the previous week.

Early predictions had suggested discharges in the range of 20,000 cubic feet per second, but the latest projection is pointing more towards 9,000 cfs (below). This will raise the river level to nearly 12 feet, and that will inundate some roadways, but nothing like the floods of 1997 when wide parts of the valley floor were under 8-10 feet of floodwaters. That's good news.

There is also good news indicated by the actions of the watermasters at Don Pedro Reservoir on the Tuolumne River. Two days ago, a lot of water was being released from the reservoir, trying to make room for possibly catastrophic river flows. Flows were up to 10,000 cubic feet per second for a while (see some pictures here). This morning, I checked the flow (below), and it has dropped back to the usual level of several hundred cubic feet per second. This means that the dam operators are confident that they can capture and save the runoff and are not worried about the dam being overtopped the way it was in 1997 (the damage from that event is still visible 20 years later). (*see new update below)

Discharge of the Tuolumne River at LaGrange Jan 8, 2017

The river surge will have some benefits: River Hyacinth, an invasive aquatic plant has been choking the channel of the Tuolumne River during the last few years. The surge of the artificial flood has no doubt cleansed the channel of the river in many places. A lot of silt that has been smothering the best spots for salmon eggs has probably been swept way, and new sand bars have perhaps been formed. Although some minor flood damage may have taken place, there is a lot of good too.

River hyacinth in the lower Tuolumne River in 2015. Those mats of green aren't supposed to be there.

The other area of concern is Dry Creek. It is an unconstrained drainage, and for a time it seemed possible to have a record flow of 8,000 cubic feet per second. Those projections have backed off a bit too, but the expected 5,600 cfs will still be the highest runoff that I've seen, and some minor flooding damage will be possible in Modesto. Notice in the diagram below that there are three peaks predicted.

Source: http://www.cnrfc.noaa.gov/graphicalRVF.php?id=DCMC1

I've been thinking about something else today. Will this spell the end of the drought that has afflicted California since 2011? The short answer is no, it will not. The storm is building reservoir levels to more healthy levels, but filled reservoirs are but a single metric in determining droughts. This warm storm has melted the snowpack, and the snowpack is what is critical to sufficient supplies during the dry summer season. The good news is that the storms later in the week will be much colder, and the snowpack may be building up. The storm does nothing about global warming, which will continue to put a "finger on the scale" each year in California towards continued droughts.

Even more concerning is the fact that the storm will only help a bit to recharge the groundwater of the Great Valley. We have developed a huge deficit in groundwater storage during the drought, as agricultural interests have pumped increasing amounts of groundwater to replace the missing irrigation supply. Even if we have the foresight to put water back into the ground, some of the storage space has been lost due to compaction. This becomes obvious when one observes the amount of subsidence of the ground surface throughout much of the San Joaquin Valley (the southern portion of the Great Valley).

Source: http://www.sacbee.com/news/state/california/water-and-drought/article31527953.html

UPDATE (1/8/17 4:50PM): The story on the drop in the discharge on the Tuolumne River is a bit more nuanced than I suggested above. I've been notified that they are trying to modulate the flow with the high discharge in Dry Creek to prevent flooding downstream of the confluence of the two watercourses in Modesto. In other words, flooding occurs on the Tuolumne at about 9,000 cfs. Dry Creek may contribute as much as 6,000 cfs tomorrow, so they've cut back on the flow of the Tuolumne to compensate.

UPDATE  (1/8/17 8:50PM): The Merced River in Yosemite Valley has just reached flood stage at 10 feet (6,600 cfs). The river is expected to rise another 1-2 feet before subsiding.

From https://waterdata.usgs.gov/ca/nwis/uv?site_no=11266500

UPDATE (1/8/17 11:20 PM): Among all the other stories of the day, word comes from Calaveras Big Trees State Park that the beloved "Tunnel Tree" has fallen in the windstorm. This is sad in one way, but it's clear that these kind of "touristy" developments like carving big holes in the base of the tree is damaging to them. We are changing nature for our own amusement instead of appreciating them for what they are. It's an unfortunate parallel that the Orca in the "Blackfish" story died this week as well.

Liveblogging the Deluge: Perspectives on the Biggest Flood in a Decade, Part One

See updates at end of post... BTW, if you are on the scene in places like Yosemite Valley, please send photos or updates! I will gladly post them here.

Printable PDF of current conditions can be found at this link 

It's clear by now that I am fascinated by the current atmospheric river storm that is blanketing the state of California with precipitation from one end of the state to the other. I'm right in the thick of it, in the Great Valley, sandwiched by mountain ranges that will be getting rain amounts measured not in inches, but in feet. On this blog, I've already talked about the last record-breaking storm, the 1997 event that caused unprecedented damage across California, but especially in Yosemite and along the Tuolumne River. I also blogged about the preparations being made in anticipation of the storm: the operators of Don Pedro Reservoir have ramped up the flow of the Tuolumne River to near flood stage to make room for storm runoff. Then, last evening, we had a spectacularly clear view of the Sierra Nevada from the valley floor, covered with snow, and seeming to wait for the coming storm event. From here on, I'll be liveblogging, sort of, the storm (it will be separate posts at times).

Radar of precipitation in Central California as of 8:00 PM Saturday. Source: Intellicast

And now the storm has arrived. Atmospheric river storms are linear streams of moisture-rich air coming northward out of the tropics (they have been called Pineapple Express storms at times). In "normal" front-related storms, the period of precipitation is fairly limited as the front sweeps through the state. Atmospheric river storms are different; they spray the state with storms that can last for days, and in some extreme examples, weeks. They are also warm storms. The snow level can reach very high elevations so that rain falls on the snowpack, melting vast amounts of ice. It all adds up to a potential for the worst kinds of floods in California.

I don't know what all is going to happen in the next few days, but I want to establish some baselines so it can be understood just what the storm means for California and our water situation. We have been in the grip of a crippling drought since 2011, and reservoirs across the state have been at historical, even catastrophic, low levels. The first diagram in this post provides a benchmark to track the changes in the next few days. It's already been a fairly good precipitation year, as some reservoirs already sit at 100% or more of their desired levels. A few are still very low, including especially New Melones Reservoir on the Stanislaus River just north of me. It is only at 27% of capacity. Lake McClure on the Merced River below Yosemite Valley is about where it is supposed to be at 47% of capacity. My special river, the Tuolumne which also flows out of Yosemite National Park, is a bit too close to full at 76% of normal. If the storm dumps too much rain in the park, it has a small chance of overflowing the floodgates in an uncontrolled manner as it did in 1997. That's the reason the dam operators ramped up flows in the last two days.

Source: California Nevada River Forecast Center

It's going to be especially interesting to see how the storm predictions pan out. The flood hydrograph above is the expected outcome in Yosemite Valley. The red dotted line is flood stage (at 10 feet, or around 7,000 cubic feet per second). Earlier predictions for the flood peak have wavered between 15,000 cfs and 24,000 cfs. The high end prediction would be of 1997 magnitude, but even the low prediction would be enough to flood valley roads and possibly close the park. The high flow history at Pohono Bridge in the valley is shown below:

Historic Crests

(1) 23.43 ft on 01/03/1997
(2) 23.43 ft on 01/02/1997
(3) 21.52 ft on 12/23/1955
(4) 20.98 ft on 11/19/1950
(5) 20.10 ft on 12/11/1937
(6) 16.96 ft on 12/23/1964
(7) 13.11 ft on 04/11/1982
(8) 13.01 ft on 01/13/1980

The current outlook is for a peak of 21,590 cfs (19.7 feet).  If it happens, it would be the 6th highest flow ever recorded. As you might expect, I'll be watching this one closely.

Flood hydrograph for Dry Creek. Source: http://www.cnrfc.noaa.gov/graphicalRVF.php?id=DCMC1

The other local river that has my undivided attention is Dry Creek. It's not a well-known waterway outside our region, but it is capable of causing some havoc at times. Although it doesn't have a vast drainage basin (it arises in the Sierra Nevada foothills in the Mother Lode), it has no dams or flood control structures. It is therefore very responsive to variations in storm intensity. I've seen it flowing at 3,000 or 4,000 cfs, but the prediction as of this evening is a bit ominous: it may peak at 8,400 cubic feet per second. Let's be clear what that means: yesterday, the Tuolumne River was flowing at 8,000 cfs, and that's considered very close to flood stage. For the Tuolumne River. A minor tributary to the Tuolumne River may be as big as the Tuolumne, but in a channel that is many times smaller. I will be out and about on Monday to get pictures, but to set a baseline of sorts, here's how the creek normally looks at the Oakdale-Waterford Highway bridge:

Dry Creek on Dec. 17, 2016 just prior to a previous high water event late last year.

So, here is where we stand with the atmospheric river storm in my backyard. We've received about a half inch of rain today, adding towards an expected 4 inches by the end of the week. If things transpire that way, it will represent about a third of the precipitation expected in my town over the course of an entire normal year. We of course are in the driest part of Central California (aside from the desert east of the Sierra Nevada), so literally everywhere else will be getting a lot more. As I've been saying in my previous blogs, be safe out there! Don't travel if you can avoid it, don't try crossing flooded bridges, and don't try walking either. If you are headed into the mountains, imagine being stranded by yourself for a few days and pack accordingly, especially with warm clothing and extra food rations. My distant relatives, the Donners, failed to do that in the Sierra Nevada in 1847, and look how they ended up. If authorities issue a flood warning, take it seriously. They're getting their advice from scientific professionals, and that still means something.

UPDATE: Officials closed Yosemite Valley roads and visitor services as of yesterday, and will reopen after the flooding subsides.
UPDATE: (although more like an addendum) For comparison's sake, here is where the reservoirs of the state were at a year ago:

A huge difference!
UPDATE (1/8, 1:52 AM): Yes, up late, listening to intensified rainfall. Gauge has picked up another .40 inches in two hours.

UPDATE  (1/8, 10:18 AM): Good morning! There was another 0.20" in the backyard gauge this morning, and now we are in a lull between major storms (most of the action is north of here at the moment). Another 2/3 inch is expected later today on valley floor. There is better news in Yosemite; the expected flood is now projected to be less than catastrophic, with a projected high flow of 9,600 cubic feet per second. Yesterday, the projection was twice that. It's still above flood level by 2 feet, but would not cover valley roads. Several more inches of warm rain is expected (~4"), but tomorrow the precipitation will turn to snow, and that is a good development.