The End of the Tuolumne River! (It's not as bad as it sounds...)

The slough at the headquarters area of Dos Rios State Park

Back in the 1980s, Douglas Adams published his hilarious "trilogy" of the Hitchhiker's Guide to the Universe. The second book, The Restaurant at the End of the Universe, was not about a restaurant at the edge of the Universe, but rather it was a place where you dined and watched the actual destruction of the Universe (you had to use a time machine to get there). 

Today's blog is about the end of the Tuolumne River. But it isn't as bad as it sounds: it's about the spot where the Tuolumne River ends by flowing into the San Joaquin River. The confluence was on privately-owned ranch lands for many years, but a profound change is coming that will touch lives across our county and Central California. It is becoming California's newest State Park!

The confluence of the Tuolumne and San Joaquin Rivers

Dos Rios State Park is the product of years of cooperation between the owners of the Dos Rios Ranch, River Partners, and the Tuolumne River Trust. In the last decade or so, the partners worked to return the former croplands to a landscape that functions like the original primeval environment that existed before the invasion of industrial agriculture. In other words, a riot of canopy trees like oak and cottonwood with a tangled undergrowth of willows, elderberries and numerous other native plants. This floodplain woodland acts as a giant sponge, absorbing and slowing down floodwaters and helping to recharge the groundwater underneath.

The lower Tuolumne River near the confluence. The state park is on the right-side shore

The riparian environment provides a marvelous habitat for the wildlife that once thrived throughout the Great Valley of California (only about 5% of that original habitat remains). Dos Rios State Park will be a fantastic place to search for hundreds of bird species (more than 200 are known from just across the river at the San Joaquin River National Wildlife Refuge), and all manner of animal and plant species. The highly endangered Riparian Brush Rabbit is only found in an extremely small area within the San Joaquin Delta and the wildlife refuge across the river. I was told they intended to transplant a small group from the refuge to the park, but that the rabbits confounded the plan by crossing the river somehow and establishing a population all by themselves!

There are a number of ancient remnant environments tucked away in corners of the park. The most striking was a growth of valley oaks growing on a slightly elevated hill adjacent to the San Joaquin near the south end of the new park. There was a cacophony of bird songs in the canopy above, including Yellow-rumped Warblers, Oak Titmouse, White-crowned Sparrows, Tree Swallows, and Bush-tits.

The oak forest is a two mile walk from what will be the park headquarters area, and there are ideas of developing the site into an environmental walk-in campsite where local children can experience wilderness only a few miles outside their cities.

Much of the park will be a trailless, roadless morass of trees and brush on the floodplain. This is the area meant to serve for flooding relief, where it might remain underwater for weeks at a time. Volunteers have spent a decade planting native vegetation, and many of the trees are already tens of feet tall. They were irrigated for three years, but they will be able to survive on their own in the years to follow, watered by the higher groundwater table and occasional floods.

A "bunny hill" on the right side, a floodplain to the left.

Several elevated areas across the park provide refuge for mammals during flooding events. I believe they called them "bunny hills". I've seen these in action during floods across the river at the wildlife refuge, where everywhere I turned, rabbits were waiting for the floodwaters to subside.

The tangled thicket of native vegetation: the valley floodplain as it once was.

One of the most valuable aspects of the park is that it will allow visitors to experience the valley habitat as it once was, and how many parts can once again be. On our tour, we mentioned the wonderful resource of the Great Valley Museum at Modesto Junior College where I teach. Visiting the museum, children can view dioramas of the natural environments of the valley and even see a few live animals. But what if...they could learn about these environments, and then drive a short distance and actually experience them? That's the incredible value of the Dos Rios State Park.

Double-crested Cormorant in the slough

When our tour ended, I spent a few moments wandering the only developed part of the park. There is a picnic area that has been constructed adjacent to the farm buildings serving as the park headquarters for the moment. There is a slough below the picnic structures with a short walkway providing panoramic views. It didn't take long to find some interesting birds, like the Double-crested Cormorant drying its wings on a stump.

I only occasionally see Downy Woodpeckers along the Tuolumne upstream, but it was the first one I sighted today. I also saw Northern Flickers and Nuttall's Woodpeckers.

A Great Egret was watching for fish on the far side of the slough. 

Turtles were basking on logs down in the slough below.

Dos Rios State Park will open this coming summer with the picnic area and slough area open for visitation. A master plan will be developed over the next few years, with proposals for a campground, trails, and all manner of interpretive programs. Even better, the park will function as an environmental buffer, providing habitat and flood protection. The park is starting with about 2,100 acres, but other adjacent tracts are being "de-developed" to resemble their original habitat. 

It was a real privilege having the opportunity to see this park and renewed floodplain in the making. I'm looking forward to seeing what lies ahead for this beautiful new park in coming years. It is a marvelous resource for our community.

Source: River Partners and the Tuolumne River Trust

Damned if You Do Dam, Damned if You...Well, Don't Dam: The Days of Dennett Dam are Done

One does not usually equate the city of Modesto with dams and reservoirs. It's true there is a Modesto Reservoir, but it is fifteen miles east of the city. But there is a dam in the city limits, and it has been a problem and an eyesore for decades. Back in 1933 someone had the bright idea of building a small dam on the Tuolumne River by the 9th Street bridge and constructing a nice park built around boating and swimming. Dennett Dam was built, and it lasted an entire seven years before being mostly destroyed by flooding. The park never materialized, and the remains of the dam lay abandoned. At some point, someone thought it would be a good idea to cut an opening in the dam to allow fish to surmount the structure and swim upstream (the Tuolumne is a salmon river).

The unintended consequences mounted. The opening set up unpredictable whirlpools in the river current, and at least three people have been trapped and drowned nearby. The structure impeded flows of the river and during low water, vast amounts of the invasive weed River Hyacinth would accumulate, blocking the migration of fish, and crowding out native vegetation. And the fish, which the opening was meant to help, were devastated by predators, especially introduced bass. The newly born fish were forced to utilize the narrow opening, and were easy marks for the predator fish waiting in the deep pools beyond.

Dennett Dam during a bad River Hyacinth year. Picture courtesy of Patrick Koepele of the Tuolumne River Trust

What was to be done? No one wanted to own the dam or be responsible for the problems it was causing. The city of Modesto set aside some funds around 2006, but unexpectedly high costs torpedoed the project. In 2010, the Tuolumne River Trust got involved and began to organizing fundraising efforts, both from individual contributions and grants from the State Lands Commission, California Department of Fish and Wildlife, California Department of Water Resources, USA Fish and Wildlife Service, and local agencies. Ultimately, $1.6 million was raised and work has begun. It's sort of a complicated process.

For one, they need to move the river out of the way, so the construction firm (Innovative Construction Solutions) has cut a temporary channel around the dam. It will be filled in when the dam is removed. The deep pools below the dam will need to be filled in.

When the project is completed, a major impediment to the migration of salmon will have been removed, and some 37 river miles will become more available for spawning. The land around the dam is slated for park improvement, although much or most of the "development" will consist of rebuilding the riparian habitat that had been disrupted by agricultural and industrial development. The river can become the treasure it has always had the potential to be.

If you want to see the progress over the next few weeks (or months?), it's easy to find. The dam is almost under the 9th Street Bridge in south Modesto. There is a pedestrian sidewalk on the bridge, so just park nearby and walk out.

Note: I stole the pun that I used in the title. Years ago my dad was working on a paper that he ended up titling "Damned if you do Dam, Damned if you don't Dam". I've always appreciated it.

Cherishing Our Rivers: A Journey on the Water with the Tuolumne River Trust

Are you lucky enough to live near a river? For much of my life I didn't have that privilege. Southern California has creeks at best, except when they were flooding and otherwise causing havoc. The creeks often flowed through incredibly beautiful mountains and valleys, but they can't be a source of life for human civilization. We're too busy using what little water there is that there is barely enough to maintain a healthy ecosystem. Southern California has to import around 85% of the water that it uses.

People who live in Northern California or the Pacific Northwest might smile when I describe my Tuolumne as a river. Compared to the mighty rivers like the Columbia it is a middling stream. The thing is, it lies about that point in the northward journey in California where the rivers provide sufficient water for local use that it doesn't have to be imported from elsewhere (indeed, much of the water from the Tuolumne is exported to the Bay Area). We depend mostly on groundwater for domestic use, and the groundwater is replenished in part by the river. Most of the river goes to irrigation, but some is allowed to flow into the San Joaquin River and on to the ocean (not willingly, it should be noted; there are some who would just as soon use all of it).

The Tuolumne River begins high in the Sierra Nevada, flowing through Tuolumne Meadows in Yosemite National Park. It plunges into the Grand Canyon of the Tuolumne, a spectacular gorge that is as deep as that other canyon in Arizona. It is briefly stopped and diverted at Hetch Hetchy Reservoir, and then flows through a lesser-known gorge (unless you are a rafting enthusiast) to Don Pedro Reservoir. More water is siphoned off, but part of the river continues through the Sierra Nevada foothills and Mother Lode, and finally flows into the Great Valley, where it joins with the San Joaquin.

A swallow swings low over the river.

That's where I found myself today, rafting a section of the Tuolumne where it flows through the foothills between La Grange and Turlock Lake State Recreational Area. I had joined the Tuolumne River Trust on their By Land and By Water Canoeing trip, where I was serving as the resident geologist (literally 'resident', as I live just ten miles downstream). It was a fine adventure for the twenty or so participants, who were helping raise funds for the Trust.

What do they do? The Trust organizes river clean-ups, restoration of regions burned by the Rim Fire, and educational opportunities for children and adults. They also do political advocacy, as a voice for the river itself in the cacophony of agricultural and urban water interests. It's a great organization that deserves your support!

The river was alive with birds, bugs and amphibians. I glanced at a bug hovering a foot or so over the river, and it suddenly disappeared in the mouth of a swallow. The swallows accompanied us along the entire length of our journey. Maybe all the oars hitting the water was stirring up the bugs! I saw an old telephone pole in the distance, and immediately recognized the huge pile of sticks and random debris as an Osprey nest. Both parents were there, along with at least one chick (barely visible to the right of the birds in the picture above).

The Ospreys were not happy with the rafters and canoers below, and let them know in no uncertain terms. They relaxed when we floated by and headed downstream.The river is a perfect habitat for these grand birds. 90% or more of their diet is fish, and they are experts at landing feet-first in river to grab unwary ones floating near the surface.

Exposure of Valley Springs Formation along the Tuolumne River

There is some interesting geology on the lower river. The cliffs we passed had outcrops of white or tan-colored volcanic ash called the Valley Springs Formation. The ash was the result of gigantic eruptions of rhyolitic magma at calderas located in central Nevada! Given the media fascination with Yellowstone "super-volcanoes", people might be surprised to find that similar calderas erupted all across the American West between 20 and 30 million years ago.

A bit further downstream there are exposures of the Mehrten Formation. It originated from volcanic mudflows related to the Cascades-style stratovolcanoes that once existed near the present day summit of the Sierra Nevada around 10 million years ago. Sediments within the unit have yielded an array of fossils including ancient camels and horses, giant tortoises, and strange 8 foot long saber-toothed salmon! Younger rocks above the Mehrten have given up Mammoths, Mastodons, Saber-tooth Cats, American Lions, Short-faced Bears, and Giant Ground Sloths, along with many other ice age species.

The lower reaches of the Tuolumne River cannot be mistaken for a world class whitewater rafting locale (you have to go upstream for that), but it can present unique challenges to amateur canoeists like myself. There are thickets of willow and cottonwood trees along the banks, and sudden turns in the river course can drive boats into a maze of branches. We had half a dozen swampings that usually happened when both canoeists ducked in the same direction as they went into the thickets. No one was hurt, but it can be momentarily terrifying.

In some places the river was constricted to where it was only a few feet wide, and the water flowed very fast. If you look at the canoe above, you can see how fast it's plowing through the water as the people oared furiously to avoid the thicket just below. The water whipped them in a circle into a back eddy.

There were also hazards caused by fallen trees. Some of them reached almost across the river, and the one above occurred just after a fast-moving chute. Being short (which I'm not!) has advantages in such situations. The Trust folks put a premium on safety. You can see that everyone had a personal flotation device, and leaders were stationed at critical points in the difficult passages to help guide boats through.

We've abused our rivers. Gold dredges did incalculable damage to this stretch of the river by ripping out the riparian vegetation and destroying the soils along the river floodplain. Miles of river habitat were destroyed by the search for a few suitcases of gold, but money seems to trump all. Over the decades the river has started to recover, but it will be many more years before the river can be truly healthy for salmon and all the other life forms that historically lived along the river (I looked for River Otters today, but unfortunately didn't see any). There are many other challenges, like the invasive hyacinth, a water plant that clogs river channels, pollution (why do we use rivers as a dumping ground?), and low flows related to the continuing drought in California (the water is warmer than it should be).

It was a marvelous day spent with people who are working hard to protect and rehabilitate this precious resource. Rivers are truly a gift, and they need to be cherished and protected. What rivers are near you, and what can you do to help?

2.0% of the Tuolumne River Story, Courtesy of the Tuolumne River Trust. And 8-foot-long Saber-toothed Salmon!

Standing on the Dana Fork, close to the headwaters of the Tuolumne River in January of 2012 (when no snow had yet fallen)

Rivers often get used as a metaphor for life. Writers might compare the exuberance of youth with the dancing streams and waterfalls at the headwaters of rivers, and the calm deep waters of the big rivers denote adulthood. And of course, there is the "Old Man River". In a way, geologists once did the same thing, designating different stages of river erosion as "youth", "maturity" and "old age". On a planet that is so active, rivers rarely follow the script of such simplicity. Rivers undergo constant change, and some parts of river systems can be older than other parts. The watersheds can be altered by mountain-building events, lava flows, landslides, and other dramatic changes in a landscape. The Tuolumne River certainly fits that bill.

The Tuolumne River flows through the flat valley of Tuolumne Meadows, the location of a 2,000 foot deep ice sheet during the ice ages. The longest glaciers of the Sierra Nevada, 40 miles long, originated here.

The river seems "normal" enough. It has headwaters high in the Sierra Nevada in Yosemite National Park, it has carved a deep canyon along the middle stretches, it flows onto the plains of the Great Valley of California, joins up with other rivers, most notably the San Joaquin (although the San Joaquin hasn't contributed significant water to the system in many decades), and finally ends in the delta complex at the head of San Francisco Bay.

But there are significant deviations. In the high country of the Sierra Nevada, the river flows across a mostly horizontal landscape for a number of miles. Tuolumne Meadows could almost be described as a swampy stretch of river, especially during the spring runoff in wet years. Then the river plunges headlong into a deep gorge, complete with waterfalls and cascades that would be more characteristic of the headwaters.

Into the river at LaGrange Bridge

Along the ridges and slopes high above the present day river, there are stretches of river gravels from a long-gone ancestral Tuolumne River, one that may have had its origin in central Nevada. Other ancestral Tuolumne Rivers lie within the sediments of the Mehrten Formation that form bluffs around the present-day river in the foothills. These mudflow deposits (and occasional lava flows) record a time when volcanoes erupted near the Sierra Nevada crest only 9-10 million years ago.

I had a marvelous opportunity to explore 2% of the river last week, courtesy of the Tuolumne River Trust. The trip was a three mile long canoeing expedition (the river is 149 miles long, thus 2% of the river), from the Old LaGrange Bridge to the Old Basso Bridge. It was a yearly event, the "Paddle with the Salmon" trip. This part of the river flows among the lowest foothills of the Sierra Nevada, just a few miles upstream from where the river emerges onto the floor of the Great Valley at Waterford.

2% of a river doesn't sound like all that much, but there is a lot of geological history wrapped up in those couple of miles of river. Old LaGrange Bridge was built in a spot where the granitic and metamorphic rocks of the river disappear beneath sedimentary layers. There are three named formations in this part of the Sierra Nevada foothills: the Ione, Valley Springs, and Mehrten formations. They encompass around 40 million years of geologic history.

Around fifty million years ago, the region was very different. The Sierra Nevada, which had been an Andean-sized mountain range throughout most of the Mesozoic Era (the age of the dinosaurs), had been deeply eroded to what amounted to low hills (in many interpretations anyway; the issue is "under discussion" in research circles). Large rivers with a source at least as far east as central Nevada flowed across what would later become the crest of the present-day Sierra Nevada. These rivers flowed into a tropical coastal complex that included swampy estuaries and extensive sandy beaches. The resulting Ione formation has been mined for low-grade coal called lignite, for clay (used in ceramics), and the beach sand has been mined for glass-making (you can tour one of the old mines at Black Diamond Mines Regional Preserve near Antioch). We drove past exposures of the Ione where we got onto the river.

The river sediments, called the Auriferous Gravels were also mined, much to the detriment of the riparian habitat of the Tuolumne River. "Auriferous" means gold-bearing (Au is the chemical symbol of gold). Miners turned the river upside down in their search for the elusive metal. They used pans and other placering methods at first, but by the early 1900s they were using large floating barges called dredges. The dredges would be floated in a newly dug pond (filled by seepage from the high water table), and giant shovels ate away at one edge of the pond. They processed the sediments for the gold on the barge itself, and then used a conveyor belt to dump the waste rock at the other end. In other words, the dredges were sailing across the landscape, carrying their ponds with them.

The biggest terrifying rapid of the day! When one of the canoes got hung up on a rock, the trip leader hopped out of her raft, walked over the canoe, and moved it along. Yeah, the river was kind of low...

The dredges remained active through the early 1970s. The dilapidated remains of an abandoned dredge can be seen just a couple of miles from our section of the river, off LaGrange Road. The remains of a dredge maintenance camp can be seen on a bluff above the river at Old Basso Bridge. One of the old dredge fields has been preserved as a county park called the Joe Domecq Wilderness.

Many of the efforts of the Tuolumne River Trust involve the rehabilitation of the riparian habitat along the river, to assist in the recovery of the population of Chinook Salmon and other native species. There is a lot of work to do. The dredges were terribly efficient, with the emphasis on "terribly". The heritage of the mining efforts are barren fields of boulders. The fertile soils are long gone.

Near the end of the rafting trip we passed buff-colored exposures of the Valley Springs formation. The layers contain volcanic ash and tuff from gigantic eruptions of rhyolite calderas (so-called "supervolcanoes"). Incredibly, the eruptions took place in central Nevada. These ash layers traveled hundreds of miles! There were Native American grinding stone holes in some of the exposures.

In the hills above us we could see ledges and cliffs of the Mehrten formation. From about 11 million to 7 million years ago, eruptions from andesite volcanoes near the crest of the present-day Sierra Nevada produced huge lahars, or volcanic mudflows that choked old channels of the ancestral Tuolumne River. The river would shift in response to the disruption and establish new channels. The rivers flowed across low plains populated by various species of camels, horses, antelope, and mastodons. There were also large Galapagos Tortoise-sized turtles, and strangest of all, 8 foot long salmon with large teeth variably described as tusks or saber-teeth. Despite the fearsome teeth, they probably fed on small prey. If you would like to learn more about the salmon and the turtles, check out the new exhibit at the Great Valley Museum at Modesto Junior College.

We only saw a few salmon during our float trip, but that was okay. We know they're out there. What we did see was 40 million years of Sierra Nevada history exposed along just 2% of the river's length. What a marvelous adventure in the past (and in the present day as well)! I deeply appreciate the kindness of the Tuolumne River Trust for allowing me to join in on their journey.