hydrology Archives - Trail Scholar

Hike with a Forest Hydrologist

Views from the Table Rock Wilderness Trail

“All life depends on it.”

This was the response I got when I asked Jonas Parker, Bureau of Land Management hydrologist, why anyone should care about hydrology. A no brainer, right? Well, sort of—Jonas elaborated, “hydrology needs to be functional. It needs to be in balance with the ecosystem it flows through.”

A System in Balance

We don’t just depend on water to live, but we depend on the regulatory processes that sustain a healthy water system.

Consider the human body—we need to take in a certain amount of water to be healthy. Too little water and you risk dehydration. Too much water and you risk overwhelming your body tissues. Our body systems help keep the body in balance, even when our choices may not. Overwhelm or abuse these systems and the consequence is death.

In the case of an ecosystem, like a forest, the same principles hold true. Too much or too little water can be devastating for an ecosystem. Natural processes and cycles help stabilize and regulate the hydrological cycle. Overwhelm or abuse these systems and we could be looking at ecological and societal collapse.

In either case, it is the system that needs looking after, not just the water flowing through it.

Land Management

As a district hydrologist for the BLM, Jonas’ job is to look after hydrological systems on our public lands. One of these lands is the Table Rock Wilderness area—which is where I met up with Jonas for our hike.

Jonas begins his descent from the meadows near Rooster Rock.

The Hike

Trailhead: Table Rock Trailhead
Distance: 7+ miles
Elevation Gain: approx 2500 feet
Details: We hiked from the Table Rock Trailhead to Rooster Rock Trailhead. Roads to both trailheads are gravel but in decent condition. Road to Rooster Rock Trailhead is a bit rough; high clearance recommended. Ample parking available. Pit toilet available at the Table Rock Trailhead.

Views of a Patchwork Forests

Ironically, our wilderness hike started out on an old road that maybe 30 years ago was used to haul away timber. So, even though our intention was to experience wilderness, we found ourselves face-to-face with industrial timber production.

The Table Rock Wilderness is a 6,028-acre swath of mostly hundred-year-old uncut forested land. It was established in the 1980s as part of an effort to protect what little remained of unharvested forests in western Oregon. However, the Table Rock wilderness is almost completely surrounded by industrial timberlands, both public and private. Therefore, when views opened up along the trail, we found ourselves looking down on a patchwork pattern of forest in various stages of production.

Beyond the Horizon

Looking beyond the horizon, the patchwork of Oregon’s forests become even more complicated. Almost half of Oregon is forested. About a ⅓ of is owned by private forest owners, while the remaining ⅔ are public forests, managed by government agencies like the BLM and USFS. A majority of the timber harvest is done on private land, where economics is often the primary driving factor. While the remaining timber harvest on public lands works to meet multiple objectives.

The BLM’s Northwest Oregon District alone manages about 800,000 acres of land, much of it secondary growth from clear-cuts in the mid-1900s. A time period when timber production and economic gains was the priority. Now, our public lands are managed for multiple uses, including timber production, but with ecological and social considerations to balance. To accomplish these goals which may seem to be in conflict with one another, much of the land that the BLM manages are held in reserve, including the Table Rock Wilderness.

In other words, much of Oregon’s forests are the product of out-of-date forest management practices that don’t necessarily jive with our current goals.

Modifying the Land

Pretty quickly, Jonas and I made our way off the road and deep into the douglas-fir/western hemlock forest. “Look at this chunk of land,” said Jonas, “diversity of species and canopy layers, appropriate spacing and correct vegetation. It doesn’t need anything.” The hydrology of this forest is functional. However, “most of the lands [in western Oregon] don’t look like this.” Most of our forest lands have been modified at one point or another. And modification changes the hydrology.

Jonas explained—”Whatever and however you modify the landscape there are going to be consequences.” For example, when a forest is clearcut, the amount of water that trees transport from the soil to the air, a process called transpiration, will decrease, as there are fewer trees to do the work.

However, if that same area becomes overgrown with lots of shrubs, or is replanted at a high density with trees, transpiration will increase again.

Each of these modifications changes the amount of water in the system which may lead to problems. For example, too much water added to the system when transpiration decreases may result in more runoff, higher stream flows, and erosion. Too little water and you may be looking at a dry streambed.

“It’s this balance of modifying the landscape to accommodate different objectives,” said Jonas, which makes his work fun.

Looking toward the Table Rock Wilderness Area.

Quality and Quantity

So when we are talking about changing the hydrology, what does that really mean?

I asked Jonas how he defined hydrology. He said, “The grade school answer is it is the study of water.” But, he added, hydrology can really be “broken down into two measurements—water quality and water quantity.” If water quality and quantity are good, then you are looking at a healthy system. However, in a modified forest, maintaining water quality and quantity can be a challenge.

Clean, Clear Water

According to Jonas, when it comes to water quality in a modified forest ecosystem, there are two factors that should always be considered in order to ensure good water quality.

The first is turbidity. Turbidity is the cloudiness of the water. In most forested ecosystems, the turbidity should be low most of the time—that is the natural state of a forest stream unless there is a rainstorm or snowmelt which naturally induces erosion and thereby increases turbidity. However, any human activity that disturbs the soil, like building roads or harvesting timber, can also mobilize sediment so that it may enter a body of water. This is a huge problem especially for aquatic organisms— it can clog fish gills and smother eggs; reduces stream visibility; and it can absorb heat. It can also make drinking water treatment more difficult.

Second is the water temperature. Most rivers in Oregon are inhabited by cold-water adapted species. However, with climate change, early snowpack melt, and the removal of forest from along rivers or streams, high water temperatures are becoming a more frequent problem. High temperatures are problematic because they can reduce the amount of dissolved oxygen a stream can hold. Warm temperatures can also lead to the growth of algae. Algae can throw the ecosystem off balance by reducing oxygen concentration as they decompose, as well as producing cytotoxins.

Keeping it Clean

However, Jonas explained, proper management can help mitigate turbidity and temperature problems. For example, maintaining a vegetative corridor along rivers and streams can provide shade that prevents water from heating up, as well as help filter out sediments. According to Jonas, the primary shade zone is about 85 ft—this is where 95% of shading occurs. These “riparian areas or buffers” are prescribed by the fish biologists and hydrologists and, in the case of BLM land, a 120 feet buffer is maintained on perennial streams where stream temperature is a concern just to be on the safe side.

In addition, to reduce the risk of damage from road construction, road use, and road work, waterbars can be placed along logging roads at regular intervals. These redirect water and sediments into the forest where it can settle out, rather than allowing it to flow directly to the stream. Jonas pointed out one of these waterbars on the road we walked in on.

Too much or Too Little of a Good thing

On the water quantity side of things, the discharge, or rate, of freshwater flowing through an area is important. Or in the case of a lake, the volume of water. And since most of the water Oregonians consume comes from forested land, modifications to forestland that changes the amount of discharge of a stream is not acceptable.

Some of the mitigation measures used to reduce pollution can also help with efforts to protect water availability. For example, directing water flowing in ditches toward the forest (as opposed to directly into the stream) can help slow its flow. A good riparian area can do the same thing. However, much of BLM land has been managed since the 1930s with a goal of intensive timber production, so they are stocked at levels that may be too dense for balanced water quantity. Remember too many trees can mean less water available to the system.

Hard Decisions

As the focus of the BLM has shifted more towards a balance between resource protection and resource production in recent years, Jonas says, “The struggle is always there to balance the economic, the ecological, and the social.” Sometimes you have to make management decisions that aren’t popular, like thinning a riparian area, in order to reduce transpiration and bring the hydrology into balance. And though it would be nice to leave things alone and let cycles restore on their own, it takes a lot of time.

“We also have threatened and endangered species—fish, owls, you name it—and their survival depends on a healthy functional riparian area. The question I would ask is, ‘Can they wait two to three hundred years?’”

A Spring!

Early on in our hike, Jonas and I found ourselves startled by a rare find—a spring right in the middle of the trail! Coldwater was bubbling right up from the ground! Jonas pointed out that the geology around us is responsible for the formation of a spring.

Geology Brief

The Table Rock Wilderness has a volcanic geological history. The basement rock in the area is a volcanic rock called andesite, probably remnants of an old stratovolcano that existed 17-10 million years ago. Layered on top of the andesite, is a different type of volcanic rock called basalt. The basalt probably formed from lava that flowed into the area and cooled about 4 million years ago from a nearby Cascade volcanic eruption.

At one point during the hike, you skirt around basalt pillars—called columnar basalt—that makeup Table Rock’s summit. One of the many cool geological sights on the hike.

Columnar basalt on the base of Table Rock.

Hidden Water

All that being said, it is the volcanic nature of the Table Rock Wilderness that influences a part of hydrology that is often overlooked—groundwater. About ⅓ of water on Earth does not flow on the surface but exists underground. In comparison, surface water—lakes, rivers, etc—makes up only about 1% of all freshwater.

In the case of the Table Rock Wilderness, much of the water that lands in the forest will infiltrate into the ground and recharge “deep, deep basaltic aquifers”—huge groundwater storage zones.

Because basalts tend to fracture, Basalt rock aquifers tend to be very permeable and porous making them ideal for supplying water to springs and seeps.

“Springs regulate themselves and fluctuate very little,” said Jonas. The Table Rock Wilderness hydrological system is in balance in part because “water that enters the aquifer is equal to the water that leaves.” He went on, “Shallow aquifers are more prone to weather and drought. But that is not what we got here. Here we are 4,000 feet up on a basalt mountain! If there is that much water coming out of the ground, that amount is going to fluctuate very little throughout the year.”

Let it Snow

After a couple of miles of hiking in the woods, the trail opens up to views of Table Rock. It was here—while hiking through a rockfall that supposedly is inhabited with Pika—I saw a glimmer of white at the base of table rock. It was snow!

Water in its many solid forms makes up about 2/3rds of freshwater on the planet—by far the biggest chunk. O.K. so most of that is probably accounted for in the polar regions. But still, glaciers and snowpack are incredibly important water reservoirs in the Pacific Northwest.

According to Jonas, snow is still the largest reservoir of water in Oregon. And in the Table Rock Wilderness, this is also the case. Though most (well, basically all) of the snow had melted by the time we hit the trail, it was still working its way through the hydrological system underground, ultimately bubbling up to the surface through springs and seeps.

Looking out to my right from the base of Table Rock, I could also see Mount Hood in the distance. Similar to how Table Rock supplies water to its creeks, Mt. Hood and the rest of the Cascades, supply water to some of Oregon’s largest rivers and most populous areas. For example, the McKenzie River is a spring-fed system—supplied by a mountain snowpack that melted, infiltrated, and has been traveling underground for several years!

Table rock sitting just above a rock fall. Can you spot the snow?

Wondering about Watersheds

After returning to the woods and circling Table Rock, Jonas and I eventually hit the switchbacks that take you to the top of the rock. Though Jonas opted to hang back, I had heard the views were too spectacular to miss, so I made the ascent alone.

It was worth it! Looking out across the landscape at the mountains, ridges, and valleys, was spectacular. It also brought me back to discussion Jonas and I had earlier regarding watersheds.

Anytime you are standing on the planet Earth, you are standing in a watershed. A watershed is simply an area of land that drains to a common body of water. For the Table Rock Wilderness this common body of water is the Molalla River.

A Drop at the Top

As Jonas described it—if you take a drop of water and place it on the top of Table Rock it will travel a number of different ways—it might travel to Image Creek to the north or Bull Creek to the south—but ultimately it will end up in the Molalla River. That is because the Table Rock Wilderness sits in the middle of the Molalla River Watershed. The Mollala River and Table Rock Wilderness are connected, even though the river never flows within the wilderness boundaries. This connection extends to the Willamette River as well. The Molalla River is the largest undammed tributary to the Willamette River.

So standing on the top of Table Rock, I was standing in the Mollala River Watershed, the Willamette River Watershed, and the Columbia River Watershed, as well as probably one or two smaller watersheds nested within.

Though I didn’t spill any water at the top (other than sweat), it was still fun to trace the journey of a drop in my mind. A practice I recommend trying next time you are on a ridge.

One of many views from the top of Table Rock.

An Uncut Forest

After visiting the Table Rock summit, Jonas and I continued along the Saddle Trail and High Ridge Trail toward Rooster Rock. These trails led us back into the forest and through some gorgeous wildflower meadows.

Taking in all the unique features of the area, Mine and Jonas’ conversion came back to a topic we touched on earlier—change. Change is part of the cycle of a healthy functioning ecosystem. In fact, the Table Rock Wilderness formed following a forest fire about 100 years ago.

View of a wildflower meadow looking up at Rooster Rock.

Things are Changing

But, Jonas asked, “What will it look like in 100 years? 200 years?” With climate change creating hotter, dryer conditions, will we see a shift away from the Douglas-fir/ Hemlock forest to one filled with Pine and Madrone? As wildfires become more frequent and severe, how will that change the dynamics of the landscape? And, perhaps most importantly, should we step in?

Wilderness areas are for the most part “untouched,” but with global crises like climate change and biodiversity loss, we need to start considering our impact on these untouched places, and whether or not we should do anything in response. “We need to acknowledge no management is management,” said Jonas.

Neither Jonas nor I had the answer, but we need to keep asking the question—How do we best protect our public lands?

Sweat Worthy

After several hours of sweating it out on the trail, Jonas and I followed the Rooster Rock Trail down to the trailhead where we had staged our return vehicle.

Overall, the hike was long and challenging, but the scenery was worth every bead of sweat. I definitely recommend hiking the Table Rock Wilderness. Just make sure you pack enough water!

Jonas Parker is a Hydrologist for the BLM Northwest Oregon District. He received his B.S. in Fisheries and Aquatic Science at Utah State University and Masters in Natural Resources Management from the University of Idaho.

Hike with a Hydrologist

The Zigzag River flowing through the forest.

Flaming clouds of airborne gases, ash, and fine sediment rush down Mount Hood at 100 miles per hour, like an incinerator in flight. A slurry of hot water and sediment, in some cases 100 meters high, and the consistency of cement, follow—crashing down Mount Hood’s rivers and valleys; rocking and rolling between ridges; decimating everything.

This is Mount Hood 1,500 years ago. This is Mount Hood at various points during its geological history. Heck! As an active volcano, this is Mount Hood in the future.

Massive amounts of sediments were redistributed down the mountainside with each eruptive period. Sediments filled in valleys and creating an eerie lifeless landscape—in effect, a clean slate.

The Beginning

Which brings me to where our story begins…

I met up with hydrologist James (Dar) Crammond at the junction of Road 39 and Highway 26 to explore the Zigzag River Valleys.

Little Zigzag River and Big Zigzag River are fed by a glacier near the base of Mt. Hood’s crater, converging to become the Zigzag River further down the mountainside. They also sit precariously in the path of destruction described above.

However, despite this, Dar and I did not find ourselves hiking through a dry, flat moonscape, but a deep valley and forested oasis. The clean slate from 1,500 years ago was not clean anymore. It had been written upon by the very substance we had met up to talk about—water!

James “Dar” Crammond standing next to a logjam in the Zigzag River.

The Hike

Trailhead: Unmarked trailhead off of Road 39 at the gate for Forest Service Road 2639-021 where Paradise Park Trail Begins.
Distance: 2.5 miles
Details: Recreation Pass for US Forest Service Trails may be required. Limited parking and no parking at the trailhead. Little Zigzag Falls Trailhead is at the end of Road 39 and is a great add on to this hike.

A Giant Reset

Before we hit the trail, Dar took me to an overlook of Mount Hood a little further east up 26 from our meeting point. As I stood there marveling at Mount Hood, Oregon’s tallest and most well-known stratovolcano, Dar explained Mt. Hood’s recent eruptive history.

In addition to the eruptive event 1,500 years ago (the Timberline eruptive period), the Zigzag episode (500 years ago) and the “Old Maid” episode (200 years ago) also sent pyroclastic flows (airborne debris flows) and lahars (water and sediment flows) down Mount Hood. In fact, in 1804-05 Lewis and Clark observed the remnants of debris flows in rivers coming from the Mountain into the Columbia. Consequently, this is how the Sandy River got its name.

The Sequence

Dar also pointed to the horseshoe-shaped crater on Mount Hood with a tooth in the middle, called crater rock. He explained that each time an eruption would occur the dome would collapse leaving a crater, but then the dome would grow and the volcano would erupt again. Crater rock is a remnant of one of these collapsed domes. Hot spots around crater rock signify the potential for a new dome to build.

In addition, the heat energy from each eruption would liquefy all of the ice, snow, and glaciers on Mount Hood. The superheated water would flow down the mountain at high speed, collecting material along the way. This “mudflow” is what is known as a lahar. Unlike pyroclastic flows, which are airborne, lahars flow down the mountainsides a bit slower, but much farther. This is why Lewis and Clark were able to observe debris from Mount Hood in the Columbia River many years ago. There is even evidence that the Columbia was temporarily dammed by lahar debris at least once following an eruptive episode.

Dar called this whole sequence “a giant reset”— as it flattens the terrain with loose sandy material and rocks—setting the stage for a new force to come in and shape the landscape—water!

Loose Landscapes

Leaving the viewpoint, Dar and I headed back to our meeting spot and drove up Road 39. At the end of the road is a parking lot and trailhead, as well a section of old Route 26 that was decommissioned in the 1960s. However, that is not why we stopped here. Instead, Dar wanted to show me an exposure that would provide some insight into the aftermath of Mt. Hood’s eruptions.

The exposure was probably 25 to 30 meters high and made up of fine textured sand. Growing along the exposure were red alder trees. Dar said, “Alders love loose landscapes” When you see red alders in an area it suggests disturbance.

Dar explained that during the 1550 eruption that a big lahar, with a peak 30% to 50% higher than what we could see, dropped down into the area where it would have been constrained as it moved down the canyon, causing it to ricochet from cliff to cliff. Eventually, the slurry of water and sediment would meet a constriction point downstream where the Little and Big Zigzag meet– blocking sediment transport and causing loose sediment to pile up. Hence, the alder trees.

Sediment Stratigraphy

This exposure was one of many Dar and I observed, as we moved downstream along road 39 to begin our hike through the woods.

Another exposure that was particularly interesting was near the pinch point where the Zigzag River tributaries meet and the canyon narrows (just above the trailhead on road 39). Here you could see horizons, or layers, of sediment from different eruptive events.

Dar explained how scientists can use organic bits found in the horizons, like a fragment of charred wood, to date each layer.

He also explained how sediment size and mixing within a horizon, is evidence for the origin of each layer. Fine, consistently sized grains of sediments signal the normal hydrology of rain and snow. While jumbled sediments of variable size and shape are characteristic of lahar deposition.

Of course, even between different eruptive events, lahar depositional characteristics will differ depending on the stage of dome-building in which the eruption occurred. Fine material is more predominant in layers from early-stage eruptions, while large angular rocks are found in late-stage eruptions that follow dome-building.

Sediment stratigraphy near the confluence of Little Zigzag and Big Zigzag.

A Reckoning

Either way, we are talking about a lot of loose sediment! This is where hydrology comes into play, explained Dar. The powerful forces of big disasters often capture the imagination, but it is during the aftermath of these moments, where the real work begins. It is with the power of a raindrop and the force of a river that water reshapes the landscape—tearing down what plate tectonics builds up. In this case, a forested canyon just waiting to be explored.

A Giant Sandbox

When I was a kid I loved playing in the sand at the beach—digging holes, building sandcastles, and watching the waves wash it all away. Now that I have my own children—I am fascinated by how many hours they can spend playing in the sand.

For hydrologists, this fascination doesn’t stop at childhood. Hydrologists “play in the sand” all the time. In fact, many hydrologists work with small-scale “sandbox” models. Provided enough sediment and a continuous supply of water, these models help hydrologists better understand the large-scale ways water shapes the Earth.

The Zigzag River system is important to hydrologists because like a sandbox model, it too has a continuous supply of water and plenty of sediment—but it can be studied on a real-world scale. As Dar put it—it is a “giant sandbox.”

Let’s go play!

Hydrology Basics

Just a little past the confluence of Big Zigzag and Little Zigzag, Dar and I headed into the woods near the Paradise Park Trailhead. Here we followed the Zigzag River downstream along a lovely forested trail.

Stream morphology is influenced by a lot of different factors which makes interpreting a river’s path challenging for hydrologists. Unless you can directly observe the river as it takes shape, you must rely a lot on inferences.

However, according to Dar, there are still some basic principles and observations that offer a good starting point for understanding river dynamics.

Gradient

The first of these being steepness. Steep rivers tend to be more straight—water energy is directed downward resulting in deep, narrow channels. Flat rivers tend to meander or curve—water energy is directed unevenly, cutting one bank, while slowing and dropping sediment on the opposite bank.

Streamflow

The second principle involves streamflow. Streamflow or discharge is a measure of the volume of water flowing through a channel at a given point and at a given moment. Dar explained to understand streamflow you want to consider its velocity, or speed, as well as the cross-sectional area of the river. Knowing streamflow is important because, it not only tells you how much water is available, but it correlates with the kinetic energy of the stream. High flows will have a greater amount of energy, than low flows.

Streamflow is also dynamic. Thus, depending on how much the discharge fluctuates during a day or a year, the energy of the flow and the morphology of a stream may depend heavily on the time of day and/or seasonality. Even within a channel, streamflow can vary as water tends to follow the path of least resistance- resulting in more complex stream channels, with features like meanders, pools, gravel bars, etc.

Play Pooh Sticks

So next time you pass by a river or stream, take some mental measurements of all of that water rushing by—is the terrain steep? How much water is there? Throw a couple of leaves or sticks in the water and see how long it takes them to get from point A to point B. A quick game of “Pooh Sticks” and you can consider yourself an honorary hydrologist.

Riffle-riffle-riffle

Walking in the shade of the forest, we passed a turbulent section of the Zigzag River with impressive white water. While I was admiring it and snapping pictures, Dar explained what was going on.

“This is a riffle-riffle-riffle morphology,” he said. “It is fast because of the high gradient.” In a youthful stream, like the Zigzag River, water tends to follow the quickest path downhill. This generates a lot of erosive power and downcutting. Therefore, even though it was hard to see through all the white water, the loose sediment that makes up the Zigzag river bed was moving—transported downstream.

In contrast, streams with different flow regimes or sediment supplies have very different morphologies. For instance, if we were looking at a stream with no sediment load or an older stream where the stream bed was eroded to bedrock, we would be looking at a “pool-drop-pool-drop” morphology. Or if we were looking at the Zigzag River when the eruptions smoothed everything out, a single channel would have yet to be established. Instead many small, braided channels would make up the landscape.

Riffle-riffle-riffle morphology on the Zigzag River.

Wood is a Wildcard

As important as gradient, streamflow, and sediment supply are to the morphology of a river, there is another factor of often equal importance. Dar described it as “a wildcard” when it comes to morphology—and that is wood!

As we continued following the trail downstream, we began to notice places where wood had fallen in the Zigzag River and altered its morphology.

Small Jam

One of the first examples we took note of was a small log jam. One end of a log had fallen into the stream and was still sticking out of the water on the other end—what Dar called a subhorizontal arrangement.

“There are only four or five ways a tree can interact in the water,” explained Dar. It can stick straight up and down, stick out from the bank, create a perfect dam across, or be subhorizontal in the water. Each of these creates different eddy patterns that accelerate the water in some places, scouring away sediments; while slowing down water in others, allowing sediments to accumulate creating bars or other depositional features.

With our small log jam, it was easy to see this lopsided pattern of stream erosion and deposition—there was erosion on the bank nearest to us and deposition on the opposite bank. In fact, some of the small boulders on the depositional side had been sitting in place long enough for moss to grow.

Big Jam

As we walked further along the tree-lined trail, we saw more examples of how wood was altering the morphology of the Zigzag River, changing it from a narrow, straight channel to one with increasing complexity.

Eventually, we ran into what Dar described as a “classic logjam.” The logjam was elaborate with two piers produced from tree fall on each bank. These piers slowed the water upstream, allowing for some pooling and deposition especially during high flows. In addition, the piers constricted the current—sending it through the middle of the river. The energy from the constriction was enough to scour the bottom of the stream, removing sediment, and creating a large scoop pool in the middle of the jam.

Dar also explained how logjams—like the one in front of us—form and are naturally maintained. When trees growing along a bank are undercut, they will fall into the river where they will collect sediment. If enough sediment is collected, another tree may grow in the sediment and eventually fall. So it is the repeated falling in of trees that creates and perpetuates logjams in a river.

Restoration in Reverse

Of course, one might wonder why logjams even matter. According to Dar, “wood is critical” in the Pacific Northwest. Wood naturally alters forested streams and has been doing do so long before humans arrived on the scene. Fish and other aquatic life have evolved in these wood enhanced streams. Thus, complex stream systems are essential for the survival of many of our culturally and ecologically important species, like salmon.

Unfortunately, when Europeans arrived on the scene, rivers were seen as a resource for commerce and transport. So wood, which interfered with these goals, was cleared out. Dar talked about how rivers like the Alsea and Nestucca were once wood-choked. However, with the removal of wood, they lost their complexity and their gravel. Now they are armored streams with hard rock and boulder bottoms. Dar called it, “restoration in reverse.”

Now, we know better. And we have been trying to get wood back in the rivers to restore their lost functions. The Zigzag River serves as an important model for how a forested stream develops without human intervention; providing information for restoration work now and in the future.

Lost in Time

As the trail directed us away from the Zigzag River and back toward road 39, Dar’s and my conversation began to meander. I brought up a topic that seemed important to the Zigzag River story and hydrology in general—the concept of time.

“Time is the 4th dimension of hydrology,” Dar said, “it is as big a parameter as anything else.” Even 100s of years of stream data and observation only provides a snapshot of the “life of a stream.”

In hydrology, change is relatively slow. It takes time for rocks to weather and erosion to occur; for banks to undercut and trees to fall; and for sediment to accumulate. Even faster processes like streamflow are restricted by time-bound processes like snowmelt and groundwater flow. Just like it is difficult to deduce the plot of a movie from one scene, our understanding of hydrology is time-bound and limited.

As Dar and I ended our hike on the Zigzag River, I reflected on all of this.

In only a few hours, Dar shared with me a fascinating story of a river—a story fashioned from a science that is only about 100 years old. Yet it is a story that has been playing for literally thousands of years and will play for thousands more. We are just getting started.

James “Dar” Crammond is the director of the USGS Water Science Center in Portland, Oregon. He also worked as the Chief of the Water Research Branch for USFWS and began his career with the Bureau of Reclamation in 1997, where he was a water rights expert. Dar has a B.S. in hydrology and J.D. from the University of Arizona, and is a member of the Arizona and Oregon State Bar Associations.

Run Around the Alvord Desert: Let’s Playa

With the walls closing in at home, my family and I decided to head out to the Alvord Desert for some much needed solitude and wide-open space for a weekend in mid-May. The plan was to camp for a couple nights, and hike and explore during the day. The Alvord Desert is on BLM land and primitive camping is allowed. So, with the promise of room to roam, we packed up our vehicle with the necessary provisions, loaded up the car, and headed southeast.

Alive in the Alvord

The Alvord Desert is a playa located on the east side of Steens Mountain- a huge fault block mountain that runs for miles at the edge of Oregon’s Basin and Range region. Dry and expansive (about 11 miles long and 6 miles wide), with a cracked earthen floor. The Alvord Desert landscape feels alien- devoid of greenery and seemingly lifeless; a monotonous swath of dirt and dust. Much like what you would expect from a desert.

But then…

You watch the sun rise and fall, casting shadows and painting the sky intermittently between hours of moon and stars and wind. You roam the sagebrush boundary lands, hunting for lizards or other desert life. When the sun is high and the heat is too much, you swat away invertebrates while reading the book you brought on the trip, moving every once in a while in order to remain in the shade. On your early morning run, you discover large pools of water that make you reflect on what you know about hydrology (more on that later). And suddenly, you find yourself waxing poetic about this mysterious landscape called the Alvord Desert… Or maybe it is just me.

Arrival

After driving for countless miles, my family and I arrived in Alvord Desert late in the afternoon. It was finally cooling down for the night, when we found a spot to camp on the edge of the playa. There, we spent the evening watching our shadows grow long and once night hit, we counted stars and waited for the moon to rise. Eventually, one-by-one, we fell asleep to the sound of the desert winds, visions of wide-open-spaces dancing in our heads.

The Hike or Run

Trailhead: any place you can find your way back to (make sure you know your return coordinates)
Distance: any distance your energy level will allow
Elevation Gain: virtually none
Notes: Run or hike from virtually any point you would like. Bring plenty of water. Distances appear shorter in the desert, so plan accordingly. Make sure you know where you are starting from, so you can make it back safely.

A Glass Half Full

At first light, I was up and ready to explore. My plan from the get-go was to run the playa: so much space and nearly level ground- a distance runners dream, I thought. So I donned my running gear and started to move. The light of the early morning was magic, as I trotted along at my usual slow pace, soaking in the atmosphere. I followed the shrub-lined edge of the playa for most of the run. It was eerie and peaceful.

Eventually, I made it around to the opposite side from camp and figured I would cut across the playa when- splash- water! What I had thought was a desert mirage, was actually a thin lake of water that made crossing the playa at that point impossible.

Rerouting my run, questions began to soar through my mind about the wet encounter. I had read that the Alvord desert had a wet and dry season, but for some reason it didn’t fully register until that moment; until I ran smack into it.

Tired and a bit dehydrated from my run, I thought a lot about the hydrological cycle of the Alvord- about its cycles and seasons- and decided I needed to know more about this unique land of wet mud and dry dust.

Ready? Let’s Playa in the Alvord!

The Alvord Desert covered with a thin layer of water

In the Shadow

Lying within the rain shadow of Steens, the Alvord Desert is considered the driest place in the State of Oregon, receiving only about 7 inches of precipitation per year. As part of Oregon’s interior, not a lot of moisture makes it to this southeastern region. And what little does makes it into the region, is removed from the atmosphere as snowfall on Steens Mountain’s western flank. This process is known as the rain shadow effect. When moisture laden air travels up a mountainside (the windward side), it cools, condenses, and eventually falls as precipitation. The dry air then continues down the other side of the mountain (the leeward side), where it heats up, encouraging further drying through evaporation. The Alvord Desert is on the leeward side of Steens, so it not only gets little rainfall, but it experiences a lot of evaporation.

Dry and Cracked

Additionally, the Alvord basin, like most watershed in the Basin and Range of Oregon, is a closed-watershed system. Instead of taking a more traditional route to the Ocean, water in the Alvord doesn’t leave by surface or groundwater flowing to the Ocean. Instead, it stays in the basin until the hot sun evaporates it away. The result is another interesting features of the Alvord- cracks.

Alvord Desert’s surface is riddled with geometric shapes separated by cracks. Known as desiccation fractures, these cracks form as the surface of moist clay-rich sediments dry and shrink through sun and wind evaporation. Shrinking results in tensile stresses that radiate out in all directions on the surface that ultimately break, resulting in polygonal cracks- one of the Alvord Desert’s characteristic features.

Reflecting on a Thin Film of Water

O.K. so that explains why it is so very dry in the Alvord Desert, but it doesn’t explain why there is water there at all. Where does the water come from, if not from precipitation?

Perhaps not surprisingly, much of the water in the Alvord Desert comes from higher up- on Steens Mountain. Steens Mountain captures a lot of precipitation in the form of snow. Later in spring, the snowpack melts and feeds streams and groundwater systems that supply water to the basin below. Much like how water accumulates in the drain at the bottom of your sink, the Alvord Desert is one of several low points, separated by alluvial divides, that capture water draining from Steens above.

Shifting Waters

However, as a desert playa, the Alvord Desert also happens to be very large and very flat. In the spring, expansive areas fill with water but at a depth of only a few centimeters. It is the process of inundation that actually helps maintain the flatness of a playa- laying down sediments evenly throughout.

When visiting the Alvord Desert it is important to remember that these thin, but massive lakes of water may grow or shrink, and/or shift, making parts of the playa potentially impassable at times. During my morning run on the playa, it was just a matter of rerouting, but there is potential for getting stranded by these shifting waters. In the Spring, when water levels are wide, the risk of getting trapped by pooling water is particular high, so plan accordingly.

An Ancient Lake

However, even during its wettest season, the thin surface water of the Alvord is nothing compared to the amount of water it once held during its tumultuous past. From about 3.5 million years ago to 15,000 years ago, recurring ice ages increased rainfall in southeast Oregon that filled the large basins characteristic of the region. The Alvord Desert and surrounding sub-basins (as far south as Nevada) were all connected as one massive pluvial lake. Filled to the brim, Pleistocene Lake Alvord had a depth of nearly 200 feet at one point, and would often overflow.

Overflowing

During periods of overflow, water would travel via Crooked Creek to the Owyhee River. During one cataclysmic event, water burst through Big Sand Gap on the lake’s eastern rim, eroding it down about 12 m, and sending torrents of water into the much smaller Pluvial Lake Coyote, through Crooked Creek, and out to the Owyhee River. Today along Crooked Creek, you can observe the scabland terrain and boulder bars that serve as evidence of this event. Apparently, you can also hike out to Big Sand Gap from the Alvord Desert by following wild horse trails to see the breach up close- something I will have to try on my next trip.

It wasn’t until the last 10,000 years that the Earth warmed again and the Alvord became the desert you see today.

You Should Go Playa

Whether you explore on foot or otherwise, the Alvord Desert is a magical place to visit. It may look one-dimensional at first glance, but if you stay awhile, the dynamic nature of the landscape, with it’s subtle shifts and movement, begin to unfold. You should seriously go “playa” in the Alvord- you won’t be disappointing. Just don’t forget the moisturizer.

“Alvord Desert – The Oregon Encyclopedia.” 20 Mar. 2018, https://oregonencyclopedia.org/articles/alvord_desert/. Accessed 26 May. 2020.
“Playa | geology | Britannica.” https://www.britannica.com/science/playa. Accessed 26 May. 2020.
Tanner P.W.G. (1978) Desiccation structures (mud cracks, etc.). In: Middleton G.V., Church M.J., Coniglio M., Hardie L.A., Longstaffe F.J. (eds) Encyclopedia of Sediments and Sedimentary Rocks. Encyclopedia of Earth Sciences Series. Springer, Dordrecht.
O’Connor, Jim E., Rebecca J. Dorsey, and Ian Madin, eds. Volcanoes to vineyards: geologic field trips through the dynamic landscape of the Pacific Northwest. Vol. 15. Geological Society of America, 2009.
“Oregon: A Geologic History – Oregon Geologic Timeline.” https://www.oregongeology.org/pubs/ims/ims-028/timeline.htm. Accessed 26 May. 2020.