rivers

At the very end of the day today, I had an opportunity to take a short walk through the redwoods along the Eel River. I hadn't expected to be able to get very close to the river itself, we've had a fair amount of rain the past couple of days and this morning when I went over Fernbridge the river was toward the high end of winter "normal."

But where the trail I'd picked pretty much at random approached the river , there was a large gravel bar, and the water had receded quite a bit since this morning. So I was able to walk down onto the gravel for a while.

One of the things I had to adjust to when I moved west was the different behavior of rivers here. In the Midwest, I was accustomed to rivers that had been channelized, straightened, which of course increases the gradient, and they usually had downcut. Even some fairly large rivers had done this.

Here, rivers like the Eel flow through mountainous terrain with steep slopes. The Franciscan formation often includes unstable material, easily eroded, and landslides are common. This of course has been tremendously aggravated by human activity; where forests were cleared, erosion increased. This peaked in the 1950s and 1960s, when large-scale mechanized logging became common. During the big storms of 1955 and 1964, entire clearcut mountainsides collapsed into streams.

Clearcutting was common in the Eel River Valley until very recently. With the bankruptcy of Palco and the gentler hand of the new owners, things seem to be moving in the right direction. But it can take decades for sediment to move through a system, especially when that sediment consists partly of cobble and gravel. I'm told by old timers that the Eel is now wider and shallower than it once was, and that deep pools are less frequent now. Although I've not made an effort to measure, it's a fair assumption that interstitial spaces (the openings between boulder and cobble in a clean stream) have been choked with finer sediments, sands and silts. These interstitial spaces are important, because they are used for winter refugia by young steelhead and other salmonids. Clean gravel substrate is also important for Pacific lamprey, which once were common enough to give the Eel River it's misnomer, courtesy of some taxonomy-challenged early settler.

The photo above is interesting, because it shows various successional stages. The gravel bar in the foreground of course is active riverbed during winter high flow events; although it's not really visible without a close in-person look, there was plentiful evidence that it had been under shallow water only hours before I stood on it, and there was fresh fine sediment deposition in some of the low depressions. At summer low flow, the river here is shallow enough to wade without getting much more than ones ankles wet, in fact there is a trail crossing at this location.

On the far shoreline is, first, a narrow band of willows right at the water line. Behind these, red alder grow, a pioneer species which is common on slightly higher parts of the floodplain. Redwoods rise above and behind the alder, on a higher floodplain terrace which floods only very infrequently. Eventually, up the slope and out of the frame, these will transition to Douglas fir.

Behind me as I took the photo, on the sunnier west-facing bank, the riparian band was much wider and included, besides the willows and alder, some fairly large bigleaf maple.

The photo was taken in the heart of 60,000+ acre Humboldt Redwoods State Park, so much of the riverbank is protected for a considerable distance upstream. Still, the Eel has challenges. An important one is the diversion, at the Potter Valley Dam, of most summer flow south into the Russian River Valley to feed the vineyards and cities of Sonoma County, and to in turn replace water diverted from that river. Water allocation in California is something of a shell game, and the ecological consequences are profound.

There is also continuing sediment input from private lands and National Forest lands in the upper watershed. The brown water is plainly visible in the photo, even with receding post-storm flows, the sediment load remains high.

Once, in the big storms of 1986, I stood on a small bridge in Mendocino County where Elder Creek enters the South Fork of the Eel. The entire watershed of Elder Creek is within old-growth forest on protected lands. I looked down into deep aqua blue water, nearly free of silt even as I heard boulders banging off one another below the bridge in the high flow. A few hundred feet more, and that clean water entered the raging brown waters of the Eel.

Perhaps one place to advance the restoration process is in those tributary watersheds. Few remain that are even mostly old-growth, but given enough time forests regenerate. Once they do, the steelhead and coho and chinook that fight their way up the Eel will have good quality streams to spawn. The Pacific giant salamanders, torrent salamanders, and tailed frogs I've seen in high-gradient tributaries of the Eel will persist.

The river itself is a bigger challenge, and there are some major battles yet to be fought. It is too large a system to attack in a physical sense, except in a few key places. But if human induced impacts can be reined in to a sustainable level, the river will eventually, over decades, begin to heal itself.