Archive for the ‘oakland water’ Category

After Oakland’s Big One, expect a rush of water

8 September 2014

In the days since the South Napa earthquake of 24 August, the people and press appear to be astonished as the local streams have filled with water. The Chronicle published a good summary yesterday. But this always happens with a decent-sized earthquake. It will happen here. You can expect to see this stretch of Lion Creek, in the middle of Hegenberger Expressway, full of freshly released groundwater.

hegenstream

There were widespread reports of this kind in 1857, after the the great Fort Tejon earthquake of 9 January:

On a range of hills, about fifteen miles from the coast, in the district of San Fernando, we understand that a surveying party have discovered quite a large stream making out of the mountain and down a cañon, where, to their knowledge and complete satisfaction, not to say to their sorrow, no water was running or could be found previous to the earthquake. By the letter from Tejón, it will be seen that a similar circumstance occurred in that vicinity. Los Angeles Star, 17 January 1857

Just back of my camp was the dry bed of a stream, where in heavy rains water had at one time run; in this bed two weeks before I had sunk a well some 20 feet hoping to find water, but at that depth the earth was so dry I gave it up as fruitless. Two days after the first or heavy shock a little stream of muddy water was running by my camp which continued to increase each day, until when we moved was quite a little rivulet: no doubt the result of some new fissure in the mountain. Letter of W. E. Greenwell, U.S. Coast Survey, 24 February 1857

The effect upon some of the artesian wells in this neighborhood was remarkable: for a moment the water ceased to flow from the pipes, and then gushed out in greater volume and with more power than usual; we have heard that the channels of other wells, which had become obstructed, and ceased to discharge water, have become re-opened and the subterranean current is now flowing out from the orifice. San Jose Telegraph, 13 January 1857

The water goes away after a few weeks. UCB geologist Michael Manga explained the phenomenon in a talk I attended in May of last year: The shaking settles the bedrock, which in turn forces the groundwater it contains upward. In effect, the rock’s permeability in the vertical direction increases as a result of basement consolidation. This is the same basic mechanism that creates quicksand. Studies after the 1999 Taiwan (Chi-Chi) earthquake showed that this water would be replaced in about 140 years—which is coincidentally the average interval between large quakes on the Hayward fault in the last thousand years. The effect takes place within a rupture length of the fault—that accounts for the response of wells in San Jose to a Southern California earthquake whose rupture ran about 360 kilometers, from Parkfield to Cajon Pass.

Oakland’s droughtproof lake

5 September 2014

I’ve been walking around town a lot this year, and our perennial streams still have running water even in the third year of severe drought. If we still had any natural lakes, I think they’d be suffering, just like our reservoirs. But we don’t. Whatever else happens, we have Lake Merritt.

lakemerritt

Lake Merritt isn’t like other lakes: it’s an arm of the Bay. So let’s relish our luck and make the most of our inexhaustible, droughtproof “lake.”

Mine creek at Twitter Court

17 August 2014

I’ve shown you the ugly orange streambed just below the old McDonell pyrite mine. Farther downstream, the creek (which I’ll name Mine creek) emerges from private backyards next to Mountain Boulevard at Twitter Court.

mine-creek-at-twitter

It’s still pretty orange here, from extremely small (colloidal) particles of iron oxide minerals that form as the acid drainage from the mine is neutralized. The creek enters a culvert here and disappears. Somewhere under the Warren Freeway, it joins Lion Creek on its way to the bay. Lion Creek appears next as Lake Aliso on the Mills College campus, and unless the lakebed is all orange too, the pollution has been fully neutralized by that point. As I’ve said before, the pollution looks awful, but without chemical tests we can’t tell if it’s poisonous. Iron oxides by themselves are not a great hazard.

Courtland Creek cut

19 July 2014

Courtland Creek runs just south of High Street; presumably the valley was a footpath long before High Street was laid out in the 1800s. It has the peculiarity of crossing the old alluvial fan without cutting out a floodplain, as shown here in the geologic map.

courtlandcreekgeo

I visited it a few weeks ago. As you go upstream along Courtland Avenue, this dirt road appears. Dirt roads are always interesting in this city.

courtlandcreekrow

It’s the old right of way for the Key Route line, and it leads to Courtland Creek Park, a cool streamside strip with some understated concrete work meant to evoke the history of the area. At one point there’s some unusually elaborate rockwork leading down to the creek itself.

courtlandcreekrockwork

Farther upsteam, too, is a cut into the side of the Maxwell Park hill; this view is looking back west.

courtlandcreekwall

And at the upper end of the park is one of those excellent mosaic trashcans that make this city so special.

courtlandcreekcan

As I’ve mentioned before, the topography of this part of Oakland, in the Allendale flat, suggests to me that the drainage has switched between streams at various times. It will be fun to poke around here some more.

BTW please see the Q&A page for an announcement.

Casting pond, upper Lion Creek

26 June 2014

One of Oakland’s most beautiful places is tucked in the woods next to the Warren Freeway at Carson Street: the casting pond complex of McCrea Memorial Park, along Lion Creek. Entering the park took my breath away the first time I visited.

castingponds

Lion Creek leaves the grounds of Holy Names University and runs in a steep gorge behind Elinora Avenue, evading the freeway for a short stretch that includes the park. Horseshoe Creek joins it at the south end, and the combined stream enters a culvert beneath the freeway running to the Mills College campus.

This part of the streambed is highly engineered. The 1947 topo map shows an ordinary stream valley here with an intermittent stream indicated, so the wide glade for the ponds was built and the stream shunted aside. Farther downstream are some empty ponds whose purpose I don’t know; perhaps one of you does.

lion-creek-at-mccrea-park

The woods have made the area their own. This was once part of Leona Heights Park, which was cut in half by the freeway, and a pedestrian bridge that may be Oakland’s least-used one connects the two sides.

Lion Creek restoration

5 June 2014

Down at the mouth of Lion Creek, at what most of us still think of as Coliseum Gardens, the authorities have undone a bit of historic damage to the habitat. A rehabilitation project dug a new channel next to the existing culvert and installed water gates at both ends to manage the flow—brackish tidal water at the Bay end and floodwater at the hill end. After four years, it’s looking the way it was intended. Here’s the view downstream from the Lion Way overcrossing, with the Coliseum in back and the Lion Creek Crossings community all around.

coli-gardens-creek

Here’s the map view. The airphoto is kinda old, but it shows you the plan.

coli-gardens-map

The ground where I was standing is mapped at about 8 feet elevation. The other end of the park is approximately where the historic coastal marsh started, so they’re doing the right thing for this location. The culvert is still there to handle floods, but a real creek bed evolves to coexist with floods. So what we have now is sort of a zoo creek. I’ll take it over what was there before.

Cost estimates vary from $4 to $5 million to create this acre and a half of habitat. Looked at another way, that’s what it costs to lose a plain old natural creek bed, doing what it does best.

More from the City of Oakland

Alameda County calls it a “natural channel”

Alameda County Flood Control district calls it “a natural bypass creek”

Arroyo Viejo emerges

13 April 2014

Quietly, at the edge of the Coliseum station parking lot, Arroyo Viejo comes out of hiding from beneath Hegenberger Expressway. It runs under the walkway to the Coliseum and joins Lion Creek just short of the bay.

arroyoviejomouth

Even in its coffinlike culvert, the stream wants to curve, laying a gravelly point bar on its left bank and trying in vain to erode the angle of the culvert’s course into a nice meander. Sorry, old creek.


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