"Spring" Arrives in California's Great Valley

Now that I've got your attention, let's get to the post (explanation below)

In the great Central Valley of California there are only two seasons -- spring and summer. The spring begins with the first rainstorm, which usually falls in November. In a few months the wonderful flowery vegetation is in full bloom, and by the end of May it is dead and dry and crisp, as if every plant had been roasted in an oven.

John Muir, My First Summer in the Sierra

It's true, really. Winter doesn't exactly happen in the Great Valley (called by some the lowly Central Valley). While much of the country lies buried beneath snowdrifts, and people wait longingly for the first signs of spring somewhere around March, we watch the grass growing. Sure, we have some deciduous trees that turn bright colors and drop their leaves (still waiting for that to happen, by the way), but many of our oaks are evergreens. As Muir noted, the spring begins with the first rainstorm. He mentioned November, but our storms came a few weeks early. And like magic the parched valley is already turning green again.

For various reasons, it's been about two weeks since I've walked our nice little river trail where the Tuolumne River leaves the Sierra Nevada and flows into the Great Valley. The last time I was there, the landscape was parched. It had been nearly six months since any rain had fallen in the area, and it showed. There were weeds and dry grass everywhere, and every step raised a puff of dust. Then "the storm" happened, a record-setting late October storm that dropped two inches of rain in two days. A few days later, the green grass was sprouting everywhere. There is an entirely different feel to the Parkway Trail now.

I lived in an area that had winter seasons once, spending two years in Reno, Nevada, at 4,500 feet. I recall driving from Reno into the Central Valley at Christmas, struggling through a snowstorm on Donner Summit. When we reached the valley floor, it was warm (!), and I could smell the chlorophyll in the air. The greenery was stunning after what had been a month or more of snow storms. And that's what central California is like for most of the winter. It's the reason that Arctic birds like the Sandhill Cranes and Snow Geese like to spend the winter on the valley floor. They have access to food throughout the winter.

The storms of course had a huge effect on the river flows in the Sierra Nevada. Last weekend, we saw the effects of the rain in Yosemite Valley. The runoff of the Merced River resembled flows in early spring (at least for a few days). The Tuolumne River was less changed. The flow of the river is controlled by the turbines of Don Pedro Reservoir, a huge dam about 20 miles upstream. The river flows through a number of pools, and the reflections of the sky were beautiful. This was the spot where I saw some River Otters a few weeks ago (you can be sure that I'm always watching for them).

The water was so calm and peaceful. Occasionally a Hyacinth floated by, which explains the picture at the top of the post (turn the picture upside down and it will make more sense). The Hyacinth is actually a scourge throughout the rivers of the Great Valley. It is an introduced species that grows rapidly and chokes river channels. It causes oxygen levels in the river to plummet and many animal and plant species can't compete with the weed. The drought exacerbated the problem, as the rivers were not able to flush out the channels of the weed. Luckily, this year there was a bit of extra water, allowing higher surge flows that seemed to clear some of the channels. There is certainly less hyacinth along my stretch of the river.

It was nice to be home for a few days! We'll enjoy our "spring" for a while. When spring arrives for most other people, we'll be sliding into the dry summer season, and then I'll be jealous of you...

Fall in the Sierra Foothills

It's California, so the season "fall" doesn't always have the same panache that it might in the northeastern states or northern Rocky Mountains. It also comes a lot later. Except for the (somewhat) unusual inch of rain we had last week, these days would be largely indistinguishable from summer. Dry, dusty, and only a little bit cooler (highs in the eighties are expected this week).

Still, it did rain last week, so the air was cooler today, and there was a freshness we haven't felt in months. We took a little picnic this afternoon up the Tuolumne River into the Sierra Nevada foothills. We stopped at Old Basso Bridge, a river crossing that was once the focus of some rather intense gold dredging. Numerous ponds from the mining days dot the landscape, filled with groundwater. Today they provide habitat for wildlife, and a nice recreational area for fishing and wildlife photography.

The old Basso Bridge was replaced with a sleek modern concrete edifice that dominates the view from the boat ramp, but a short walk provides a view downstream towards the old bridge (which is closed to autos, but available for pedestrian use).

The old dredge ponds provide a surprising sight for this time of year: lots of flowers. There were hundreds of what looked like Brown-Eyed Susans.

The other interesting sight at the park are the boulders they've used for rip rap to reinforce the base of the bridge. They are chunks of a deeply oxidized conglomerate that is found locally in a layer called the Ione formation. It formed in Paleogene time as rivers flowed over the not-quite risen Sierra Nevada. The rivers had their source in central Nevada or more distant regions, and flowed through a landscape much different than that of today.

The rivers ended in an estuary/delta complex along the Pacific Ocean (the Central Valley was a shallow sea at the time), and in a series of swamplands that later produced lignite coal that was utilized during the settlement of California after the Gold Rush. Fossils of palms and other warm weather vegetation indicate tropical conditions.

The conglomerates also contained significant amounts of gold (hence the local dredging activity). There were a couple of guys panning gold today, and they actually had come up with 20 or 30 pinhead-sized flakes.

Fall is just beginning. I'm looking forward to some color (of the leafy kind) in the next few weeks!