ContentsPutah and Cache: UC Davis

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To Establish a Home

Daniel Leroy

Uprooting

1872-1873

Where the old creek channel swings north there stood a tree on the south levee. Half of its roots were reaching up the slope and half of them were reaching down toward the creek. It was a big oak tree—a valley oak—big enough that Peņa's cattle used to hide under it when the sun was hot.

In heavy rain years water would ride up along the bank, right underneath that tree, before swinging north, toward Davisville. In wet years Putah Creek would overtop its banks and flood the town. After passing Davisville, the old creek dipped south again, toward the Carey ranch, and vanished into the "Sink of Putah," where the levees tailed off and the water spread out into the tules.

It was one of those heavy rain years, in 1872 or 1873, when the water scoured out the soil around the roots of the old tree so that the tree fell in and took the levee with it. The water punched through, sending the uprooted tree down along a cow trail, straight away east toward the railroad tracks, the whole time cutting a new channel across the Peņa property.

According to Davisville farmer John Charles Wilson, no human had a hand in turning the creek out of the old channel. "It turned itself out," he told a court in 1928, all on account of that tree. But after the break the ranchers south of Davisville, their ranches flooding, banded together that winter to dig out the new channel. Dragging "Fresno Scrapers" behind horses, they dug the new "South Fork" channel as straight as they could along the section line, from the cattle trail clear on out to the tule. To contain the water, they built levees out of the soil they dug up.

For the first couple of years after the break the old channel was deeper than the new one and the creek continued to follow its old path. But as the break deepened it gradually became the main channel of the creek. In 1875, ranchers along the north channel tried to prevent the water from following its new course by fashioning a bulkhead out of wooden planks where the tree used to be. The bulkhead washed out a year later. From then on, the South Fork was the main channel of Putah Creek.

1998-present

Many of the ecological problems facing Lower Putah Creek, are representative of the pressures facing all riparian lands in California. These pressures include dams, diversions, channelization and clearing of vegetation for agricultural and urban development.

Dams

Completed in 1957, Monticello Dam effectively separates the upper and lower Putah Creek watersheds into two isolated systems, blocking the passage of fish and other aquatic life, and preventing the movement of sediments downstream. Sediment deposits following flood events are critical to the establishment of early-succession riparian plant species such as cottonwood, alder and willow. Trapping of sediment behind the dam has also contributed to channel incision by preventing the build-up of new sediments in the streambed downstream from the dam. The dam also dramatically alters the creek's flow regimes by altering the frequency, timing, and magnitude of flood events.

Diversions

The creation of the Solano Diversion Dam in 1959 resulted in diversion of water from Lower Putah Creek to Solano County for municipal, industrial, military and agricultural uses. As would be expected, the greatest impact of the project on riparian ecosystems in the lower watershed has been its dramatic effect on flow regimes. According to a 1992 study, average flow rates dropped 78%, from 375,000 acre feet per year before the project to 82,500 afterwards. Lower volume in the creek elevates stream temperatures, which has been shown to be detrimental to native fish. Lower flows also limit the frequency and magnitude of flooding, reducing soil inundation and groundwater recharge, both of which are important to riparian plants.

In addition to an overall decrease in annual flows, the change in the timing of flood events has significantly altered both the aquatic and riparian systems downstream from the diversion dam. Before the diversion, flows in the creek would drop dramatically between spring and summer, from 750 cubic feet per second (cfs) to 13 cfs, resulting in a water level drop of several feet. Post-project flows, typically fluctuate only from 46 to 33 cfs seasonally, which would correspond to a drop of only four inches. High winter and spring flows are necessary to scour out streambanks—exposing the bare soil by removing branches, leaf litter and other organic matter—and to deposit fresh alluvial material; peak flow events thus prepare the banks for cottonwoods, willows and other pioneer species to germinate. High-water events are also important for populations of anadromous fish, which are adapted to historic peak flow conditions.

Channelization

In the 1940's the US Army Corps of Engineers constructed levees along parts of Lower Putah Creek including the created South Fork channel. Constructed from compacted earth excavated from the creek channel itself, these levees are 20 feet wide at the crown and 80 feet wide at the base. They vary from 3 to 12 feet above the surrounding floodplain. Along with gravel mining, these levees have led to a deeper, straighter channel, which has had dramatic consequences on the surrounding riparian ecosystem. Levees, like dams and diversions, prevent important geomorphological processes like stream meandering and flood events. Meanders enable the creek to scour out old vegetation on the outside curve, where the flows are fastest, and to form gravel bars on the inside where the stream velocity is slower. Both processes create conditions suitable for early-succession plant species and the wildlife they support.

High levees with deeply incised channels also separate a creek from its floodplain. The floodplain surrounding Putah Creek has always depended on periodic flood events to replenish its groundwater supply. Lack of flooding due to the levees has contributed to a dramatic decline of the water table around the creek. This, accompanied by excessive groundwater pumping for crop irrigation, has significantly depressed the water table in the lower watershed. In one study, researchers estimated that today's water table may be as much as 13 feet below levels at the time of European settlement. Not only does this make water less available to riparian plants but it dramatically affects the creek's ability to maintain itself throughout dry periods. Historically, during the dry season some reaches of the creek would periodically dry up, but groundwater from the surrounding floodplain would flow back into the creek, maintaining pools. These pools were critical to the maintenance of both aquatic and riparian ecosystems during the summer months.

Vegetation Clearing

Excessive clearing of vegetation for agriculture and flood control has drastically changed the once vast riparian ecosystem along lower Putah Creek. Estimates of the expanse of this historic ecosystem range between 22,000 and 65,000 acres. The lower of these numbers would have meant a continuous strip of riparian vegetation 1.5 miles wide along the full distance of the creek. This strip, with its multi-layered, biologically diverse mix of trees, shrubs, vines, grasses, rushes and sedges, provided critical habitat for the watershed's terrestrial wildlife. Studies indicate that the width of the riparian zone along that same stretch today varies between 400 and 1000 feet. Clearing of riparian vegetation has also had severe impacts on the aquatic ecosystem in the creek itself. Removing riparian vegetation lowers shade levels, elevating stream temperatures. It also reduces the input of detritus, which constitutes the foundation of the aquatic food chain, and reduces snags, overhangs and rootmasses, which provide cover for fish against predators and create the slow flows and pools necessary for breeding.

The disturbance created by removal of riparian vegetation also makes the land highly vulnerable to invasion by non-native plants. Aggressive agricultural and rangeland weeds, like yellow star-thistle (Centaurea solstitialis), milk thistle (Silybum marianum), and exotic annual and perennial grasses often require open conditions with ample light for seed germination. Removing the large shade-trees in the riparian zone creates ideal habitat for these invasive species. Restoring the riparian ecosystem, once significantly invaded, is a difficult—perhaps impossible—task.

Envisioning

This is your new home:

A boxy ranch-style house on a block of boxy ranch-style houses, identical but for their different shades of off-white and their trim and their shutters. This is your home, a network of concrete avenues, drives and cul-de-sacs, closely-cropped lawns and fruit trees and brush piles. Your home, under the terraced clouds you can only see well from beyond the subdivisions. The low western range in a cloud of haze and the megalith to the east, invisible—but always the awareness of the megalith—and the overwhelming sense of flat between.

And this also is your home: between Cobb Mountain and the Yolo Basin, and between this narrow band of leafless willows and this levee. Beside the single spreading tree among the skeletons of last year's thistle speckled white with seed chaff. Among the valley oaks, invisible—but always the awareness of valley oaks.

And the awareness of a one-time forest along this creek, also your home. Complex and multi-storied, with trees above shrubs, shrubs above grasses, and wild grapevines threading the seams. Beside the water, white alder, black, red and sandbar willows, box elder, cottonwood, Oregon ash, blue elderberry and blackberry. Bushy clumps of Barber's sedge, expanses of creeping wild-rye and pipevine. Up the slope, coffeeberry, coyote bush, wild rose, live oak, mugwort, bunch grasses, valley oak and the showy-colored lupine and poppy. This place too, alive only in your imagination, is your home.

You like to play God, or Gaia, with your bundles of yellow flags, determining the fate of other creatures. You'd like to think you're different from those that made this place the way you see it—took its timber, soil, and gravels, choked its flow, cut its channel—but you are the same. Your values are different but your act is the same, driven by the same hubris.

But perhaps you've justified this, because while you are doing, you are also undoing. Undoing 156 years of violent acts committed against this place by your kind, you're transforming your new home into the home it once was for the green or furry or scaly creatures, and everything else that might have been before. This is what you tell yourself to comfort yourself. You call it restoration, rehabilitation, enhancement, creation, reconciliation—but the act is the same: it is the enforcement of your vision for the land, however informed, inspired or enlightened you think it is.

Your first task to materialize this vision is establishment. The yellow star-thistle, milk thistle and other introduced annuals require open sky to out-compete the native trees, shrubs and grasses. Riparian lands are realms of deep shade. You need to hold back the invasive annuals that strip the soil of moisture and cover every inch of ground, and put the natives in—trees, shrubs, sedges, grasses. Get their roots down to the water table. Let their bark harden up. Let them make their own seed and spread out. You need to let the trees grow tall enough for perches and nesting sites, the shrubs grow dense and scraggly enough for cover. Let them produce berries for birds, bark for beetles, leaves for aphids, and then let it all wither and die in its own time, and decompose, and become the substrate for new life. Establish it, then let it become itself, dark and uninvasible.

Your home is loose and flexible depending on the scale, a nested hierarchy corresponding to a series of geographical locations contained within one another. What you call home depends on where you are in relation to it. When you're abroad, your home is your country. When you're in your country, it becomes a particular state or region. When you're in your "hometown," your home becomes your actual house, or the turf it sits upon. In the political hierarchy, your home is 95616: in the city of Davis, in the state California, in the United States of America. It is both recognized and claimed by all levels of government. It is represented by boundaries, nested rings on a map.

Bioregionally, your home is substantially different, but no less relative and hierarchical: it is in the watershed of Putah Creek, in the Putah-Cache bioregion, in the Shasta nation, on Turtle Island. Adopting the bioregional sense of home gives you "an imagination of citizenship in a place." You live in a community defined by natural features, inclusive of humans, and also of birds and bugs and bunchgrasses and sedges and shrubs.

Ecosystems, too, are considered by most ecologists to be a hierarchy of nested sub-systems. The boundaries of each sub-system are delineated according to their degree of "connectance," based on the number and degree of interactions between system components. At the largest scale, interactions are weak and infrequent, but they become stronger and more frequent as the scale decreases. This concept of an ecosystem corresponds to the bioregionalist view of community. At some point in the shrinking of circles, connectance officially becomes strong enough to be "local," and "community" may happen.

Whatever the scale, your notion of home is flimsy and flexible. By virtue of your movement and migration, it unravels into conceptual strands. The physical location of "home" changes depending on the circumstances. Examples of these strands might include:

The Practical Home

Definition: This is where you live and work. It is where you are now, if you're not on vacation. It is where you sleep at night, and store your stuff.

Hints for how to find it: Look for the place you would write on your tax form or voter registration card. If you own a car, look at your license plate. Look for your pajamas and toothbrush.

The Rational Home

Definition: This is the home you need a formula to figure out. It may be where you have lived the longest, where you have the most friends or family, or where you spent your "formative years." Which formula you use is irrelevant. The point is that you must have some rational justification for calling that place home.

Hints for how to find it: Think of the place you tell people when they ask you where you're from, provided they leave you enough time to calculate.

The Ecological Home

Definition: This is the home that has shaped your ideas about nature. It is the non-human world you are most familiar with, the place you imagine stepping out into. It is the unkept forces at the edges of your lawn or street. You know it without ever consciously thinking about it. It is the imaginative mud off your galoshes, the arc of the sun and the rhythm of seasons throughout the year. It is the home you cannot claim; it claims you.

Hints for how to find it: Think bird or tree: what kind of bird or tree is it? Where is its native range? Think stream: what does it look like? When does it flood or freeze? What is in it, and to where does it flow?

The Emotional Home

Definition: The feeling of home here defies all formulas and practical realities of where you are. It is illogical, irrational, and best expressed through metaphor. It is best experienced in smells and dreams.

Hints for how to find it: Where is the place in your imagination that corresponds to "going back?" Where is the inspiration for your nostalgia? Where is the place you couldn't stand to see change?

There are still people in the world making in one place a home that encompasses every sense of the word. There were once many more of them. They are called indigenous, sometimes inhabitory.

There are others out there too, the re-inhabitory. These are struggling to find footing, trying to make home mean something again, streamlining home into one place. And you are among them.

You are standing on the levee looking down at some version of your new home. But however many times you tell yourself "this is my home," you are unsatisfied. You want more. You want to be rooted here, a member of a community inclusive of all creatures. Standing here, with your rusted flags and dusty vision, you are suddenly aware that you want to feel home here in the deepest, richest way. And driven by some holy, optimistic faith in this act as a remedy for uprootedness, this is why you have come.

Restoring

In the fall of 1998, I helped initiate a restoration project along the South Fork of Putah Creek near Davis, California, in part as a case study of the community-based approach. I wanted to investigate the ecological effects of the project on the riparian habitat, as well as the social effects on the volunteer participants. The project, which was later named "Restoria" by a consensus of volunteers, tested various technical restoration strategies and volunteer workday approaches in order to investigate how the process of community-based restoration might strengthen human communities and redefine the relationship between humans and the non-human, natural world.

Given the severity of the threats facing riparian ecosystems in the lower Putah Creek watershed, one might question the feasibility of successful restoration projects here, especially considering that the constraints on riparian ecosystem function-flood control, irrigation, agriculture, hydroelectric power, and reservoirs—are highly valued by the community. Unless some or all of these pressures are removed, thus restoring the hydrogeomorphic processes on which riparian systems depend, human stewardship will probably always be needed to maintain healthy riparian habitat. Restoration of riparian systems along Lower Putah Creek is further complicated by the fact that these particular areas have been so thoroughly altered that few healthy remnants remain to serve as models. Restorationists are therefore forced to base their projects on historic records, which are largely unreliable and incomplete, and sites elsewhere, which may not be appropriate locally.

Recognizing these challenges, as well as my limited timeframe, I chose to focus on the process rather than the product of our restoration efforts at Restoria. A process-oriented approach considers more than just the ecological success of the restoration. These other considerations might include the social, cultural, performative, political, aesthetic, or moral aspects of the project. It is my hope that, with this approach, Restoria has benefited and will continue to benefit the ecosystem along Lower Putah Creek, the science and practice of restoration ecology, and the volunteers themselves.

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