Thursday, September 27, 2007

#60 The Old and New in Fluvanna County

In August, while the dam at the Woolen Mills was being torn down, there were also pretty dramatic changes taking place downriver in Palmyra. On a day that I am spending in Fluvanna, I retrun via the new Route 15 bridge over the Rivanna and see that the demolition of the old bridge is well underway. Just like at the Woolen Mills site, I am drawn to watch so I park at the river launch just upriver.

A workman is using a high speed grinder to flatten the rivet heads flush so that the segments they pin together can be removed. Behind him follows another with a cutting torch, severing the trusses one by one from the structure. Below, along the river bank, chunks of concrete skewerd by twisted lengths of re-rod lie stranded like the wrappings after a wild Christmas morning. A dump truck is receiving loads of debris and carrying it away.

The dust mingles with the moist air, giving the scene an vintage Virginia red-clay wash. It is still dreadfully hot and the river below the bridges gives no releif to workers in heavy overalls and hardhats. I hear the shrill back-up warning beeps from large equipment and the clash of steel buckets and hammers on concrete. My body registers vibrations from the impact of the foundations of bridge piers being ripped from the river bed.

From where I am standing, I can see the bridge being removed and beyond it, the new bridge, where workers are dodging the traffic to lay down the traffic lines. Below is the fine stonework of the old mill and lock which will soon become centerpiece to Palmyra Mill Park in the floodplain below the new bridge. And when I turn my head 180 degrees and look upriver, I see the small island that marks one of the five bridge piers remaining from another, earlier bridge, a covered one built in 1823, rebuilt in 1884, burned in 1931 to make way for the steel bridge I am watching being demolished. It’s hard to stand and watch in the heat, so I head up Route 53 to catch the Tuesday afternoon farmer’s market at Pleasant Grove.

Entering the wide gates, I am still not sure what century I am in – and perhaps that’s the whole point of the development of the Pleasant Grove complex. Wide mowed fields give way to horse fences that mark the equestrian portion of this County Park system, the athletic fields beyond the line of trees. Vendors are parked in a neat tline, their pickups backed up to small tents to shade the early pumpkins, raspberry jelly, and cut flowers being sold. Further in sits the Pleasant Grove House and its dependency, the outdoor, or Summer, Kitchen – which now houses exhibits on transportation and local history which have been installed by the Fluvanna Heritage Trail Foundation. This site marks the western trailhead of the system of trails that flanks the Rivanna between Pleasant Grove and the village of Palmyra. Here, the morticed timbers, sloping floors, and massive stone and brick chimney anchor the structure in time and place.

There is a lot changing in Fluvanna, and I wonder if at times it is dizzying for folks to travel back and forth in time, protecting the past, making way for the new. The fruits of the efforts of some very dedicated folks are being borne out at the Pleasant Grove Complex in Fluvanna.

The next two weekends bring opportunities to explore this public section of Fluvanna that’s right on the river. There’s a 10k run this Saturday, followed by the ceremonial opening of the Summer Kitchen. The following weekend brings the annual fall event, Old Farm Day on October 6. For those of us who tend to forget what’s downstream on the river below Charlottesville, just a short ride out of town, there’s a whole lot to explore.

Thursday, September 20, 2007

#59 The Chubs of Ballinger Creek

On a recent weekday in August, I was tromping down a section of Ballinger Creek in Fluvanna County helping StreamWatch put some numbers to the shape and stability of the banks and bottom as part of a watershed wide study. The low water level had the benefit of exposing much of the river bottom to view and making it somewhat easier to walk in the creek. The bedrock outcrops provided firm ground, but were coated in a thin slime of algae that foiled the grip of my river sandals. With each step, I made a careful and studied calculation of the bottom lest I end up on my butt or with a twisted ankle.

And so it was I became acquainted with the nests of the genus Nocomis – those flattened mounds of rocks that dotted the shallow bottom that I had casually and unknowingly trampled. Three of the seven species of Nocomis make the Rivanna their home – the river, bull, and bluehead chubs – and they are fairly common. Once I learned what I was looking for, I saw them everywhere in the creek.

Each spring, males of the Nocomis species get to work, first excavating a pit on the bottom and then building a gravel mound on top of it. Only 4 to 6 inches long, these comely looking fish push, shove, and carry in their mouths small, carefully selected rocks from the surrounding river bed. Piled onto a mound, the nest looks like a small child had whiled away her time making a rock castle in the creek, but indeed it takes the male chub up to 30 daylight hours of hard work collecting the stones of his castle. Then the male chub crafts a small trough in the top -- and sets to work attracting his mate, announcing his readiness by a swelled head, horny bumps on his forehead and often a change in color. The name of the bluehead chub is derived from its nuptial coloration, while the river chub turns a bright pink. This takes place in late spring and early summer – each species wired to the spawn by the lengthening days and resulting rise in water temperature.

Once spawning has occurred, the male covers the trough, and the eggs settle into the spaces between rocks where they develop within the safety of the structure. The male chub defends his nest against males of his own species – and other fish such as suckers who would eat the eggs. Like a coral reef in the ocean, chub nests are a hub of activity and play an important role in stream ecology, for the male actually shares his nest with other species such as dace and shiners, who also use it for spawning. Many of these associated species turn brilliant red, transforming the nest into an underwater neighborhood brightly lit like a hot night in the city. All the activity attracts other, larger fish who have their own dinner in mind.

Now in late August, all that’s left is the pile of rubble and my curiosity about these enterprising, engineering fish. Some chub are known to build nests of over a thousand stones – and can carry rocks that are almost half their size. Why do they do it? Besides the safety from predators, the chub males are providing an environment for developing eggs above the river bottom where they might be smothered by sediment. While other fish species use the oxygenated waters of small riffles in which to lay their eggs, chub create their own oxygen rich environment with their nests above the sand and sediment of the bottom.

A Cherokee legend describes the Ugunsteli (or "horned fish") and his brightly attired band of attendants, holding court under the cold waters of mountain streams, a story which accurately describes the relationship between chub and the species who share the nests. The presence of nest-building chubs indicates that desirable conditions exist – and, in creating their own centers of life, the chub are contributing to the aquatic health of the stream. But Ballinger Creek’s drains an 18 square mile watershed is downstream from Zion Crossroads. Under intense development in Fluvanna County, it’s a good watch for signs of degradation, and like a male chub tending its nest, a good one to watch over.

Thursday, September 13, 2007

#58 Rebuilding the Rivanna at Bentivar

Originally Aired on April 19, 2007 (the week of the VT tragedy)

It’s another cool spring day, faint sun intermittently lighting up the pale greens and golds of emerging leaves. I am walking down a rough road from Bentivar Farm onto a vast floodplain. Sretched out before me are acres of lowland and wetlands that reach toward the point where the North and South Forks of the Rivanna meet. I know the banks from the river, having paddled both forks many a time, but today I’ve come to see restoration taking place in the flesh of the land itself.

My guide is Carolyn Browder, a restoration specialist for The Nature Conservancy, under whose care this bottomland has been for the last couple of years. She meets me by a small, unassuming stream at the bottom of the hill. It is here that, over a year and a half ago, the work commenced. The work of redefining the course of water flowing down from the surrounding hills so that it can do so without hauling loads of sediment and stormwater runoff with it.

Carolyn tells me parts of the story as we walk along stream, barely six feet across, and still running full from the rain of the last couple of days. Bubbling across a stretch of cobble, the water drops a foot over a large piece of cut rock, which has been placed strategically where an elevation decrease must be achieved without sacrificing the integrity of the channel. This channel has been purposefully rerouted to follow its historical course. Walking the moist ground, we can see where the rains had forced the water over the banks, the ryegrass bent like a comb-over and still mashed flat in downhill direction.

For decades, this rich bottomland was farmed, but it required work to drain the water from the floodplain enough to make planting corn even possible. This was accomplished by digging ditches to drain the water, and by using tile drains, terra cotta pipe sliced lengthwise and planted open side down, cupping the earth, while capillary action pulled the water along its course and towards the river. Meanwhile, the original stream coming down a crease in the hills above was routed so that it no longer bisected the fields and instead was tucked up against the hills lest it impede the work of farming this swatch of floodplain.

Land alternation had been heavy and significant long before this ditch and drain method was ever used. We know that earliest settlers set to work to clear the land, transforming forest into field, changing the relationship between the river and its floodplain forever. On the North Fork and the South Fork, indeed all along the Rivanna, you can see today the steep banks caused by the incessant erosional forces of mud-laden water washing off cleared land. In fact, the floodplain here sits some twenty feet higher than the river. This meant that the engineers designing a more natural stream channel had to build in a series of drops and slopes that would bring the watercourse into the river at a shallow and benign angle.

Carolyn’s job has been to oversee the work and continue to monitor its success as a restoration – making sure that the new stream reaches an equilibrium with its newly created banks and plateaus. That the disturbed land is kept clear of invasives such as Johnson grass. That high energy storms, such as those resulting from Katrina and Rita in the fall of 2005, don’t wash out the new stream as it’s settling in. That the right time to plant trees to form a protective buffer on either side is chosen wisely.

As we cross the stream, at another ledge of rock placed to create a drop and small pool that is now home to diversity of life, I start to gain an appreciation for the scale of the project. Looking back, I can see the sinuous curves, etched by clumps of grass and sedge that paint the landscape in subtle hues of green. A plover twitters across thirty feet in front of us towards the stream, disappearing into a camouflage of sandy soil and clumping grass. Every pool and every curve that is reinforced with boulders was conceived, then built, to give water a chance to be a stream in a channel that’s been designed s close as one can get to “natural.”

My boots are covered in muddy soil and there is a wide and open sky above. In a week that has been draped in horror and sadness so close to home, it feels particularly to good be walking a landscape that is surely in the process of change and healing.

Thursday, September 06, 2007

September 7, 2007

#57: The Right (River) Shoes for the Job:
Geomorphology at Preddy Creek

Today is my third day of walking streams, not a bad way to spend a hot and humid summer morning – and I have finally mastered the footwear problem. The first two days, I wore my Chaco water sandals. No problem getting them wet, of course, but every step was an opportunity for pea-sized gravel to become wedged between the sole of my foot and the sandal, resulting in a pointedly painful step that reduced my progress to an awkward hobble until rectified – and just as soon as I had dislodged the offending rock, another would take its place. But now, I’ve discovered that an old pair of cheap canvas hiking boots not only keeps the gravel out but provides support and traction on the slippery rock outcroppings of Preddy Creek where today, I am working as a volunteer on a river morphology study with StreamWatch.

Getting up close and personal with the sand and gravel is exactly what this work is all about. We are here to classify the stream according to a system devised by Dave Rosgen that will help scientists and managers in our watershed understand better how the tributary streams are performing as streams – in other words: can the creek efficiently move its collected waters downstream? Are its banks relatively stable, or are they eroding in such a way as to alter the channel’s form? Is the stream in some state of equilibrium with its floodplain?

The analytic tools used to answer these questions include the Rosgen classification method – and this in turn requires that we measure the shape and curviness of the channel, the width of the floodplain, the slope of descent, and the distribution of the size of particles– the sand, gravel, cobble, boulders, and bedrock that make the channel what it is, in this moment of time. From these measurements, a host of ratios are derived – and finally a classification.

Today, we’re taking measurements along the stretch of Preddy Creek immediately upstream of the StreamWatch biological monitoring stations – as are all the sites selected for this geomorphic study. Tributary to the North Fork of the Rivanna, Peddy Creek originates in the rolling hills on either side of Route 29 where Albemarle and Greene Counties meet. Though the stream seems to adequately support aquatic life, downstream stretches have been designated as impaired by the Virginia DEQ due to excess bacteria. For a lot of reasons, it’s an area to keep an eye on.

Turning onto Route 670 at the big red dome of the Sheetz gas station, we have a front row view of acres of land cleared and graded, the contours draped with rows of truck-sized boulders lined up to check the flow of runoff during the construction of the retail and residential buildings that are on their way. Branching roads named Hickory, Fir and Willow, feed into the subdivision’s main road, Preddy Creek Drive. Access to the creek is in down the gas-line right-of-of way, a grassy swale that is mowed to the edge of the creek. We clamber down the bank into the rough cobble laid to protect the pipeline and start upstream to take our measurements, soon finding ourselves in the shaded cover of trees. My boots gush expelling water with each step and I am grateful for their heavy protection, even as I sink to my knees from time to time in small pools.

We work with measuring tape, stadia rod, and transit – gathering the data which in turn will be compiled with other data, such as land use, impervious surfaces cover, and habitat assessments, to see what correlations can be made between the health of Rivanna’s creeks and streams and the way the surrounding land is being used and changed.

River morphology is defined as a tool for diagnosis – for understanding how the life history of a river and its watershed has influenced – and is influencing the conditions we currently find. Webster’s goes further, saying that the science seeks a genetic interpretation of land and water features. This intersection of terminology between the science of rocks and the dynamic world of flowing water affirms for me, once again, that the river does have a life of its own, a purpose and a role – to collect and convey water and materials downstream. To be the instrument of erosion, collaborating with gravity and weather, to work the land into new shape and form.

I suppose this is what we’re trying to replicate with our earth-moving equipment and engineered stormwater management. Like naming our streets for trees and our subdivisions for creeks, we often fall terribly short of the real thing. Even giving Preddy Creek a stream-type classification, which will be the result of today’s work, will only go so far in understanding what the stream is all about. Perhaps that small piece of rock that was worrying my foot is another, equally important way to know a river.