Archive for the ‘oakland water’ Category

Drains to bay, an Earth Day message

22 April 2010

earth day

Some things are as obvious as gravity: Here’s the drain. There’s the bay. The geologist knows this so well that it never needs to be stated. The earliest thinkers of modern geology, as far back as Nicolas Steno in the 1600s at least, recognized that rocks arise from the everyday process of mud washing downstream to the sea. The signs are obvious in the petrified ripple and current marks, the fossilized sea creatures and the sandstones as clean as the stuff of beaches. “Drains to bay” might as well be written on the geologist’s coat of arms.

The rest of us need occasional reminders. Many of us never gave it a moment’s thought, probably those same Oaklanders who think that bears live in the woods up on Skyline. Earth Day is for them, the ignorant. Ignorant people are not bad people. Indeed, they’re only selectively ignorant, in that they don’t know something I consider important. Surely I’m just as ignorant in terms of what they care about. Anyway, “drains to bay” is a good start and it needs to be pointed out everywhere, even here where it’s obvious on Embarcadero East at the mouth of 14th Street Creek.

Earth Day, too, should always point out the basics. The rest of the year is for learning more and for putting knowledge into daily action—for Earth Life.

“Drains to bay” means that what we throw away doesn’t go away, any more than the ancient ripples and prehistoric creatures are totally lost.

Creek mouths

7 February 2010

Down at the Martin Luther King Shoreline Regional Park, three creeks debouch into San Leandro Bay. I already talked about San Leandro Creek; the other two are Lion Creek, below (more about it here and here), and Elmhurst Creek, bottom.

lion creek

elmhurst creek

Maybe with all our recent rain, they carried some sediment down to the bay, but probably not. Today both creeks are culverted to within an inch of their lives.

Old-fashioned water filtration

16 January 2010

On the path up to Chabot Dam, you pass this row of big tanks (click for big version).

water filtration

They were used to filter the water from Lake Chabot reservoir, and they’re still filled with fine sand plus, I suppose, the decades’ worth of slime and crap they kept out of Oaklanders’ stomachs and food.

This is roughly the same purification method we rely on when we use well water. The fine pores between mineral grains purify groundwater in two ways. First, of course, they physically trap the crap. Second, the minerals themselves chemically attach to many dissolved contaminants. Clay minerals are especially important for that.

The days are long gone when Oakland was served by wells. The water table has been pulled down all over the city by human intervention. The headwaters of Lion Creek were once called Laundry Canyon because there was so much good water coming down. Fruitvale irrigated orchards for many years. The rains we get here can’t keep up, so now we pipe our water in from the Sierra.

One important feature of the new state water compact, if they can ever get it nailed down, will be a new, wide-scale program of monitoring groundwater. We need that to get a handle on the whole resource. Everyone knows, except the statutes, that surface water and groundwater are intimately connected. Western water law is an ass.

Lake Chabot

20 December 2009

Lake Chabot is a reservoir, but geologists still agree with laypeople that it qualifies as a lake.

lake chabot

That said, reservoirs differ from most lakes. They have steep banks and deep middles. This gives them a greater variety of habitats. They have jagged planforms on the map because they intrude up every little tributary valley instead of developing a nice rounded shape. And, of course, they’re temporary by any geological measure.

Around here, most lakes form as a result of tectonic activity or landslides. Lake Temescal started out as a sag pond on the Hayward fault. Clear Lake, farther north, formed when a landslide dammed a fork of the Russian River. It rose until it spilled eastward down Cache Creek, which has captured the watershed. Lake Chabot is about 50 feet short of that level; if Anthony Chabot had built his dam higher, the lake would now spill south into Castro Valley.

The valley of San Leandro Creek is so steep and its walls so high that I can easily picture it collapsing regularly, especially during big earthquakes, to have made ancient Lake Chabots in the past. So today’s lake isn’t so unusual for the region.

San Leandro Creek (2)

16 November 2009

San Leandro Creek is Oakland’s largest watercourse. Before Anthony Chabot dammed its upper reaches and the Bay shore was filled in, the creek was navigable up to East 14th Street. Where you enter the M. L. King Regional Shoreline at Hegenberger Road, San Leandro Creek looks quite capacious.

san leandro creek

Today the creek no longer has a lazy, sinuous course but instead runs down a straight ditch to its mouth near the Coliseum. The water looks wholesome, there’s wildlife all around, and the fishing seems to be good. Today’s paper showed men pulling sardines out of the bay here.

san leandro creek

An elaborate observation tower offers a view of San Leandro Bay, an unsung body of water between Alameda Island, Bay Farm Island and the mainland. My visit was near high tide; the map shows it as almost all mudflats.

san leandro bay

The spear of grassy marshland is Arrowhead Marsh. One story has it that the marsh was created in 1879 when Chabot’s dam construction, accomplished with hydraulic hoses, washed an enormous quantity of sediment down to the Bay. If so, that would be just another item in the long list of damages done to California during early statehood. But just as likely is that it was always there, along with 2000 more acres of marsh stretching across today’s airport and in a wide fringe around San Leandro Bay.

Here’s a view of the creek’s course across the East Oakland flats.

San Leandro Creek (1)

8 July 2009

san leandro creek

San Leandro Creek isn’t the only stream crossing Oakland’s flatlands, but it stands out more than others. First, it’s the trees. Second, the flats are more extensive in southernmost Oakland. In north and central Oakland, the big Pleistocene alluvial fan sticks out from the hills leaving only a narrow lowland strip.

Arroyo Viejo and Temescal, Sausal and Peralta Creeks have tree trails too. But those streams have been extensively culverted and covered, whereas nearly all of San Leandro Creek is in daylight. You really see the creek as you ride BART south of the Coliseum. But all of the creeks are landmarks once you start to notice them.

This view is from Dunsmuir Ridge. See the creek’s mouth here.

Merritt Slough

3 July 2009

merritt slough

When Oakland was first settled, a large wetland extended inland from the tidal channels east of Alameda Island. Samuel Merritt took it upon himself to improve the marsh with a dam, and the resulting brackish water body was named Lake Merritt. Today the lake is closely regulated with a water gate beneath 7th Street, and this creek runs both ways depending on the tide. Not even the Oakland watershed map gives this stream a name, so I’ll call it Merritt Slough. Click the photo for a 800×700 version.

The bank on the right side is the south bank, or the left bank. It’s nearly in its natural state, whereas the other bank is part of an area of made land a couple hundred meters wide. I’m standing just off E. 10th Street, next to the Civic Auditorium.


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