Out on the California Prairies: Taking Stock of California's Most Powerful Storm Ever

There are many ways to describe the power of a storm: monetary damages from flooding, rainfall totals, rise of reservoirs and rivers, and others. So one can argue about which particular storm was the most powerful to ever hit the state. I'm thinking especially of storms like those of 1861-62 that left much of the Central Valley as a vast lake for months, the 1997 floods that overwhelmed some reservoirs in the Sierra, or the 1969 floods that I experienced in Southern California. They were all devastating floods, and yesterday's storm won't be remembered the same way as these disasters, but in two ways this storm apparently was unique. 

The storm was called a "bomb cyclone", a term that meteorologists apparently hate in the same way that geologists hate "supervolcano". In any case, the power of the storm lay in the intense low pressure cyclone spinning in the ocean offshore of California and the Pacific Northwest. The lower the pressure, the higher the pressure gradient force that controls wind speed. The pressure was a record 942 millibars, and this generated hurricane-force winds over the ocean. Inland, vegetation and mountains slowed the gales, but we still had a wild day in the Central Valley, with trees and telephone lines down.

The Tuolumne River at Roberts Ferry Bridge

Storms can be incredibly powerful in terms of winds, but as I've discovered in Death Valley National Park, without a source of moisture, that will be it: powerful winds. But this storm tapped into subtropical moisture from the general vicinity of the Hawaiian Islands. This band of moisture, termed an atmospheric river, carries vastly more water than even the Mississippi. This stream of atmospheric moisture was pushed upward as it encountered the frontal system of the cyclone and it produced a prodigious amount of relatively warm precipitation. A number of all-time records for one day storm totals fell across the state, including downtown Sacramento, which got 5.44", breaking a record that stood since 1880. That represents 69% of all the rain the city received in the entire rain year 2020-21. Blue Canyon in the Sierra Nevada got 10.40", which amounted to almost a third of the entire 2020-21 water year. 

I headed out onto the prairies of the Great Valley and the Sierra Nevada foothills this afternoon to see what the atmospheric storm did to the grasslands. My first stop was to check out the Tuolumne River at Roberts Ferry Bridge (above). The river hadn't changed much, as it takes time for the waters to gather the storm runoff and move downstream, but the river is also controlled by the huge dam at Don Pedro Reservoir, and they'll hold onto as much water as they can. It's currently at 48% of capacity, which is bad, but not as bad as most other Northern California reservoirs (Lake Shasta is at 22% or so).

The biggest effect on the Tuolumne will be in downtown Modesto where Dry Creek joins the bigger river. Dry Creek is a normally...well...dry creek that has headwaters in the foothills north of Modesto Reservoir. It is undammed, so it can occasionally produce large floods that can back up into some residential neighborhoods. It had a minimal flow over the last few weeks of a few cubic feet per second. But I could see that a lot of water was gathering out in the prairie. The picture above shows one of the small tributaries to Dry Creek, and channels like this are present all over the region. By tomorrow Dry Creek may be flowing at close to 900 cubic feet per second.

The prairie for the most part was certainly wet, but there were few visual reminders that a vast amount of rain had fallen overnight. The vernal pools held water and creeks were flowing. But little flooding and soil loss had taken place, with one glaring exception. Tens of thousands of acres of prairie have been uprooted to be be replaced by almond groves. These groves have been planted in nice neat rows up and down the hillsides, providing a convenient avenue for floodwaters to cause intense soil erosion. I passed numerous scenes like that above where mud from the orchards had flowed down the road. It's hard to believe in this day and age that the farmers would be making the kind of mistakes that led to the Dust Bowl in the 1920s in Oklahoma, Kansas and Texas.

Away from the almond groves, the grass roots held the soil in place, and the water was infiltrating underground and flowing gently in the recently dry creek beds to gather and eventually drain into the Tuolumne River. The birds and other life seemed enervated by the moisture and were very active throughout the afternoon. I saw lots of Brewer's Blackbirds, Western Meadowlarks, Savannah Sparrows, Red-tailed and Ferruginous Hawks, American Kestrels, and Ravens. I loved coming across the small herd of horses; I was reminded that horses evolved on these prairies millions of years ago before migrating into Asia. They later became extinct here in North America only to be 'returned' by the Spaniards in the 1500s.

The final thought about today's storm is knowing that after the warm rains that snow would be falling in the high country of the Sierra Nevada. In the webcam from the Yosemite Conservancy we can see that upper Yosemite Valley is now mantled with the cold white stuff. Many wishes that this could be the start of a good water year with a chance to recover somewhat from our devastating drought.

The Prairies of California: the Most Extraordinary Landscape (and Ecosystem) in California

The Tuolumne River on the east side of the Great Valley

I admit this statement is a hard sell, especially among those who live here, but hear me out: the Great Valley prairie is the most extraordinary landscape and ecosystem in California. 

The Great Valley prairie remnant east of Modesto

"But", they will say, "the valley is boring. It is just one long flat plain full of farms, feedlots, oil derricks, and urban hellscapes. It's dusty and the air is bad. And there is nothing to do." And from their point of view, their statement is valid. But that's not the part that I am talking about. I'm talking about the valley that once was, and more importantly, the 5% of the valley that is not given over to agriculture and urban development. It is that small bit that teaches us what once was. 

I was thinking a lot about the original valley today.

Prairie and wetlands at the San Luis National Wildlife Refuge south of Turlock

The occasion was World Migratory Bird Day, Global Bird Weekend, and eBird's October Big Day. The purpose of the day is to gain a one-day snapshot of the world of birds, and birdwatchers all over the world contributed observations. For myself, I decided I wanted to capture as much of the primeval Great Valley prairie as I could, so I selected three habitats for the day: the valley wetlands and marshes, the riparian environment, and the dryland prairies that once filled the spaces between the rivers and wetlands. In the end Mrs. Geotripper and I explored the Merced National Wildlife Refuge and the San Luis National Wildlife Refuge, and in the afternoon I walked the Tuolumne River Parkway Trail (as I often do). As the sun began to set I took a drive through the prairies between the Tuolumne and Stanislaus Rivers east of Modesto. In all we saw nearly 60 species of birds.

One of the most extraordinary facts about the prairie lands of California is that they ever existed at all. The Great Valley is 400 miles long and 30-40 miles wide, and with the exception of a single volcanic center at Sutter Buttes, is as flat as any place on Earth. The entire American West is characterized by rugged mountainous topography, including the Coast Ranges and Sierra Nevada of California between which the Great Valley is sandwiched. Such a large mostly flat region is akin to finding a serene quiet lake surface in the midst of an intense hurricane.

The origin of the Great Valley lies in the violent tectonics of the subduction zone that existed off the coast of California for at least 200 million years. A region of oceanic crust was being driving beneath the western edge of the North American continent, forming a trench and a deformed mass of sediment called an accretionary wedge. Parts of the accretionary wedge were buoyed upwards to become the core of California's Coast Ranges.

As the slab of ocean crust sank into the Earth's mantle, portions of the plate melted and formed vast plutons of magma that melted their way through the overlying continental crust, forming an extensive volcanic chain called a magmatic arc. The deeper parts of the magmatic arc eventually cooled to become the granitic rocks of the Sierra Nevada.

Between the geologically violent wedge and arc though was a shallow sea that simply collected sediments washed off the land. This sedimentary trough is known as a forearc basin. As the sediments accumulated, they pressed the crust downwards, providing room for additional sediments. Eventually these silt and sand layers reached a thickness of 25,000 feet or more. These sediments became the floor of the Great Valley.

Source: National Park Service

The valley was below sea level for most of its first 140 million years, but in the last four or five million years the floor of the valley was lifted slightly above sea level to become the plain it is today. It is dry in large part because the adjacent Coast Ranges act as a barrier to incoming storms from the Pacific Ocean. It is literally a desert in the southern portions from Fresno to Bakersfield, but the dry plain is crossed by numerous rivers flowing out of the Sierra Nevada.

In antiquity the valley was a vast prairie, a grassland stretching 400 miles from what is now Bakersfield to Redding. The drylands were broken up by a system of rivers, marshes and wetlands that supported groves of oak, cottonwood, and sycamore and vast thickets of willows and shrubs. These plants supported a rich fauna.

Until roughly 12,000 years ago, the prairies were populated by millions of grazing animals including horses, camels, deer, elk, bison, and even elephant species like mammoths and mastodons. This megafauna was preyed upon by a terrifying roster of predators including saber-tooth cats, 
lions, cheetahs, dire wolves, and bears, including the California Grizzly and the even larger short-faced bear. The cause of the extinction of most of these species is still debated, but the prime suspects are climate change and overhunting by newly-arrived humans. A minority view argues for an asteroid impact that primarily affected North America.

Sandhill Crane and Great Egret at the Merced National Wildlife Refuge

In the aftermath of the extinctions, the valley still supported a robust ecosystem. The mild winters provided shelter for millions of migratory birds, and the grasslands were grazed by elk, deer, and antelope. Predators included wolves, coyotes, foxes, mountain lions, and bears. The Tule Elk were thought to have been hunted to extinction in the years after the Gold Rush, but a small remnant of the species survived on a single ranch at the south end of the valley. The California grizzly and wolves were eliminated in the early 1900s. 

Tule Elk bull at the San Luis National Wildlife Refuge. We didn't see any today so I borrowed a shot I took in 2016

Today the remaining original prairie and wetlands environments are present due to sheer luck, and from concerted efforts by many environmental organizations and government agencies. A series of national wildlife refuges have been established like a string of pearls up and down the valley to provide habitat for the millions of migrating cranes, geese, swans and other species.

The White-faced Ibis is a tropical species that looks almost black until the sun shines on the iridescent feathers. The white face appears in the breeding season.

Some grass prairies are preserved in state parks and national monuments (most notably Carrizo Plains National Monument). But most persist because they are on cattle ranch property. These private lands are threatened by the rapid expansion of almond groves into the foothills. In my county alone, tens of thousands of acres have been planted, with no secure irrigation sources for the thirsty trees. I'm pretty sure they'll be abandoned within a decade or so as the groundwater they are using dries up.

Dry Creek, shown here, has earned its name this year, although it is capable of serious flooding in wet years. An invading and misguided almond orchard can be seen at upper right.

The riparian habitats have their own problems. The river woodlands are among the least-affected environments as attempts to develop them as farmlands tended to fail because of repeated flooding. Still, much damage was done in the attempt, and current efforts are directed at replanting native species in floodplains that have reverted to government or conservancy ownership.

The Tuolumne River near the Sierra Nevada foothills.

It is the rivers themselves that face the biggest challenges. There is no more contentious issue in the Great Valley than water use and distribution, especially in severe drought years. All of the major rivers are dammed and strictly controlled except for the occasional exceptional flood. The Tuolumne has been kept at a minimal flow, enough to maintain a string of river water into the delta. The slow-moving water is subject to warming to a dangerous level for river species, and the expansion of invasive species like river hyacinth. Through it all the river is a beautiful walk at all times of the year.

Sandhill Cranes at the San Luis National Wildlife Refuge

It was a serene day, but it was also the calm before the storm. The migratory birds are beginning to arrive in greater numbers, and soon these pools will be filled with Snow and Ross's Geese, Tundra Swans, and Aleutian Cackling Geese. There is nothing quite like seeing a flock of 10,000 geese take off all at once. It becomes so easy to imagine what once was in this most extraordinary place.

California's Rarest Ecosystems: The Prairies and Vernal Pools (Part One of a Two-part Miniseries)

The lower foothills of the Sierra Nevada are one of the most unique and almost universally ignored parts of California. Caught between the famous and heavily-visited forests and alpine regions of Yosemite's high country and the utilitarian agricultural fields of the Great Valley, the lower foothills are made of soils too poor to be developed, and too "plain" to be noticed by people rushing up the highways to the mountain resorts. For much of the year they seem barren and lifeless. But these prairies are one of the most precious of California's diverse ecosystems.

The prairies of California once extended the length of the Great Valley, a 400-mile-long grassland supporting millions of grazing animals, birds, and predators, including Tule Elk, Pronghorn, Deer, Grizzly Bear, Mountain Lions, Coyotes, Foxes, and numerous rodents, reptiles, amphibians, fish, and insects. In earlier times (more than 10,000 years ago) there were camels, horses, bison, giant ground sloths, Columbian Mammoths, Saber-tooth Cats, and Dire Wolves.

There were also modern-day wolves, and it is ironic and coincidental that a wolf returned this week to the Great Valley for the first time in a century. It is a young male from Oregon who made an epic journey through Modoc County into the Sierra Nevada near Yosemite Valley, and then into the Sierra foothills of Fresno County, and across the Great Valley (including two freeway crossings). At last report it's now in Monterey County (it's wearing a radio transmitter). 

The prairies were covered with native grasses that were quickly replaced by invasive species when European colonizers arrived and started herding sheep and cattle. Farms eventually replaced the ranches, and the remaining prairies, no more than 5% of the original land cover, were relegated to the fringes where the soils were poor and no water was available for irrigation. Those remaining prairies form a belt through the foothills of Sierra Nevada.  A narrow remnant can be found along the Coast Ranges and the Carrizo Plains west of Bakersfield.

The prairie soils in the Sierra Nevada foothills are notably poor in nutrients because they have not been part of an active floodplain in tens of thousands of years, and the fertile components have been leached away, leaving behind reddish iron oxides and thick clays. Differential settling and wind deflation has left small hollows and depressions that collect rainfall during the relatively rare winter storms. The clay prevents the water from seeping underground, so pools will persist for weeks or months at a time. These pools are the basis for one of California's rarest ecosystems, the vernal pools.

The vernal pools are islands of diverse life in the otherwise barren grasslands. Numerous species of plants and wildflowers, amphibians, and invertebrates have evolved to survive the weeks of water and the months of dryness. As the waters evaporate away, one species of plant after another germinates, grows, and goes to seed. The pools are often rimmed in colorful zones of different flowers.

I'm writing about the vernal pools today because the limitations of travel in the times of a pandemic have kept me pretty close to home. I live on the edge of the prairie between the Tuolumne and Stanislaus rivers and I was out there today. A few pools are left, and flowers are blooming across the region. The views are expansive, extending to the snow-capped peaks of the High Sierra.

The pools and plants provide food and cover for multitudes of bugs and other wiggly organisms, so the pools are trafficked by a large variety of birds, and dozens of species can be identified by discerning and observant individuals, and occasionally by me as well. 

I saw a half-dozen American Avocets in one pond a few weeks ago.

The prairies are one of the best places to see the rare and threatened Burrowing Owls. The area around Crabtree, Willms, and Cooperstown Roads are among the most dependable places to see them in our region.

Savannah Sparrows are a common species, and they'll occasionally cooperate with photographers.

The Western Kingbirds seemed to arrive from their winter homes in Mexico all at once last week. I saw none a week ago, and dozens today, including this one that hung about long enough for a picture.

I have no picture, but I came upon a Gopher Snake in the road that was in serious danger of being run over. I stopped, looked at it carefully to make sure it wasn't a rattlesnake, and then I picked it up to put it in a safer spot. I was suddenly reminded of how Gopher Snakes sometime pretend to be rattlers! They can flatten their normally narrow heads into the triangle shape of a rattler, and will strike in a similar manner. I didn't hold it for long...how do you explain to the EMTs that you picked up a rattlesnake that you thought was something else?

If you are lucky enough to live near a California prairie, this is a good time of year to explore them. If you tend to rush through this unique part of the Sierra Nevada and the Great Valley on your way to Yosemite or some other mountain destination, slow down and give these precious and unique lands a quick look. You won't be disappointed.
 

California's Precious Disappearing Prairies: A trip to the Willms Road Pond

One of California's precious landscapes is being lost, again. The state once had a vast prairie extending for 400 miles from Redding to Bakersfield. The grasslands were of course put to the plow, and agriculture rules the environment today. Less than 5% of the original grasslands of the Great Valley remain, and they've been under renewed assault in just the past few years.

The problem is nuts, and specifically almonds. The valley and nearby hills produce 80% of the world's supply, and they constitute the largest agricultural export we produce right now. The trees use prodigious amounts of water, but that hasn't stopped a vast expansion of the orchards into the remaining prairies on the east side of the valley where the Sierra Nevada foothills begin. With a crippling drought and no reservoir irrigation possible, the landowners are simply drilling wells and pumping the water from the ground. The supply of groundwater is limited and in severe decline. I am pretty sure these wells cannot provide more than a few year's worth of water before they'll be dry.

Still, the prairies aren't gone yet, and I took a break from taxes this weekend to catch the sunset from Warnerville and Willms Roads east of Oakdale. We drove through miles of newly planted orchards, and into some of the grazing lands beyond. It was a stunning reversal from the appearance last year of dead grass and dry streambeds. We've had adequate amounts of rain on the valley floor, with upwards of 10 inches in December, and a few good storms in February to make up for a record dry January. The grass was green and growing, and the ephemeral streams and vernal pools were filled with water. We just need more snow higher up in the mountains to get well from the drought, as the snowpack is less than 20% of normal right now, with the end of the rainy season looming.

We were following on the heels of an unusually active thunderstorm system. Our weather is pretty benign most of the time, but this storm dropped upwards of a foot of snow in the high country. The clouds were an incredible sight in the last glow of the dying sunset.

There were animals out and about. The Western Meadowlarks were present in large numbers, trying to attract some mates. They have a most beautiful song, which I captured on a brief video that you can listen to at my Geotripper's California Birds site (click here).

The story was the same with the Red-winged Blackbirds. There were dozens, if not hundreds, at our favorite little stock pond on Willms Road. They were strutting about displaying their bright red and yellow shoulder patches.

If some of the smaller animals weren't paying careful attention, they might not have noticed the hawk lurking in the almond trees. I almost didn't see it myself as we passed.

The biggest surprise came as we passed the small cliff along the creek that crossed Warnerville Road. I was expecting or hoping to see some burrowing owls, but the biggest hole was occupied by the raccoon seen below. When it noticed us, it just up and disappeared into the burrow.

The remaining prairies have persisted because no one could think of how to make money from them other than grazing cows or sheep. Now that almonds are a lucrative source of money, there is a target painted on the ranchlands in the Sierra Nevada foothills. I hope the state gets around to writing the groundwater regulations so we can get a handle on the unrestrained development that is taking place right now. It's clearly unsustainable in the long run.

Beauty in my Backyard: Sunset on the California Prairie

Blogging at Geotripper has been a bit rare of late...finals week is starting and mountains of grading have a way of pushing out other activities. Two straight days glued to the couch midst a massive pile of laboratory reports essentially drives me nuts, and I needed to get out of the house, but where to go when it is already 3 o'clock and the sun is rapidly sinking towards the horizon? The mountains beckon, but they're too far away for the 90 remaining minutes of sunlight. We headed into the prairie in our backyard, the grasslands that mark the edge of the Central Valley and the lowest foothills of the Sierra Nevada.

It's the middle of December, and winter is coming. There aren't as many ground squirrels in evidence, but that doesn't mean the local Red-tail Hawks aren't looking for them. We passed a ruined windmill and spied a pair of raptors looking for an evening meal.

These grasslands couldn't really be mistaken for any kind of pristine wilderness, as they have been grazed by cattle for more than a century. But the land is empty of people, and if you are looking for peace and solitude, this is a good place to search. The rolling hills hide geological violence: metamorphic rocks recording the rise and destruction of ancient mountain ranges, and volcanic ash layers reveal explosive activity only a few million years ago. But tonight there is only the trickling of water from the nearby stock pond, and the chatter of a flock of Red-wing Blackbirds.

We come back to the stockpond on Willms Road from time to time over the course of the year. When we were last here, the temperature was close to 100 degrees, and grasshoppers were eating everything in sight. Today, it was cold and the bugs were nowhere to be seen.

The ground was dry and parched, but there was enough moisture in the storms of November to fill the small lake and send a gentle creek across the plains. The sun was low on the horizon. We prepared to go, but as we climbed into the car, a flock of several hundred Red-wing Blackbirds arrived at the pond and started flying in circles in perfect formation. Every moment or two, 15 or 20 birds peeled off from the flock and landed in a particular section of the tules surrounding the pond. Then another group of birds landed a little further down the shore. Eventually all the birds found a place to roost. I was reminded of commuters on a freeway looking for their offramp.

As the sun landed on the horizon, we headed back into town and got some dinner at our favorite Mexican cantina. And now I am back on the couch facing that pile of laboratory reports. But I'm a lot more serene about it now...

Biblical Plague or Culinary Opportunity? A day in the California Prairie Lands

We journeyed out to the California prairie lands again today. We've now paid a visit in the fall, the early spring, and now the late spring, as summer starts to take hold in the Sierra Nevada foothills. Our destination was a small stockpond in the hills south of Knight's Ferry on the Stanislaus River. The local bedrock is composed of vertical exposures of metamorphic slate and greenstone with a covering of andesite lahar (volcanic mudflow) deposits called the Mehrten Formation.

We had one of the best rainfall seasons in many years, with around 115-120% normal rainfall, and an unusually cool April and May. When we were here in early April, the ground was muddy, and the grass was green. There were quite a few birds, but when we got there this evening, it was a great deal busier, even though the grass is brown. Part of the busy-ness involved things being splattered on the windshield and being crunched under the tires. There was a regular plague of grasshoppers, thousands upon thousands of them everywhere. Apparently the conditions were ripe for a population explosion.

I've heard of some serious problems with grasshoppers in the midwest this year, with aerial spraying of pesticides and the like, but I don't think it was going on here. There was a much more normal way of dealing with the overpopulation of the pest: birds were munching away! I'm not entirely sure why the birds were all lined up, but there was a small drainage next to the road, and I suspect the grasshoppers were more abundant on the particular stretch of road.

It's kind of creepy to get out and walk among the insect plague, as hundreds jumped away in all directions. I leaned down to take a shot of a bee in one of the few flowers, and I honestly did not notice the grasshopper looming over the flower. In fact, if you look carefully, you may notice that at least four grasshoppers were stripping away the leaves and flowers.

Still, it was peaceful in the twilight, and the songs of hundreds of satiated birds and bullfrogs was a pleasant musical accompaniment to the dying sunlight.

UPDATE: I suspect we saw an 'irruption' of devastating grasshoppers. Apparently they have caused some real problems in the past, especially in the late 1950's.