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KIP EVANS |
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all photos: CHRISTOPHER RICHARD
A walk through Dimond Park in Oakland invites contemplation of our heritage. This is the first place where ancient redwood trees were clear-cut, from the years after the Gold Rush through the rebuilding of San Francisco after the 1906 earthquake and fire. These trees have sprouted from the burl surrounding the stump of a felled giant. They are the oldest second-growth redwoods anywhere. Compare their size with that of the stump remnant to get a sense of how long it takes a redwood tree to grow. Sausal Creek flows freely through this park.
Leaving Dimond Park, Sausal Creek again disappears into a culvert. Here at the Fruitvale Avenue Bridge it enters the Oakland Estuary and its waters mix with those of San Francisco Bay.
Here Berkeley's Strawberry Creek emerges from underground, freed by the efforts of creek activists in 1984. "This was the first victory for the daylighting movement in California," says Christopher Richard.
TOM STELLER Richard immersed in his work, painting a rock to make a mold for an exhibit. |
WHEREVER YOU ARE ON EARTH, you are in a watershed. Practically
speaking, the watershed is the most useful unit for land use management
and conservation actions of all sorts: it follows the way nature organizes
and divides the landscape. Beyond that, finding your watershed, even in
an urban environment, seems to be a very good pathway to deeper understanding
of your place in the world and where it is you call home. The more you
study watersheds, the more you see the many ways that life and the land
are related.
 Just what is a watershed? It's
the portion of a landscape that drains to a particular stream, river, or
other body of water. If rain falls on saturated soil, it will "run off"
downhill. Runoff from all the hillsides in a watershed eventually will
reach the stream or river for which the watershed is named. For example,
the American River watershed is the area between the western ridge of the
Lake Tahoe basin and Sacramento; any rainfall will run off into the American
River. Across the ridge to the north of this watershed is the Yuba River
watershed; across the ridge to the south is the Cosumnes River watershed.
Of course, just as the American River is a tributary of the Sacramento
River, the American River watershed is part of the Sacramento River watershed.
Most watersheds are part of a larger watershed and, in turn, can be subdivided
into smaller watersheds. The boundaries between watersheds are called divides,
and generally follow ridge crests. The Great Divide, along the crest of
the Rocky Mountains, separates waters flowing to the Atlantic Ocean from
those that flow to the Pacific.
If you live in a city or an
urbanized area, you may need to think like a detective to discover your
local watershed. Many creeks have been confined to underground culverts
beneath streets and buildings. Although many bigger creeks remain open,
they may run in concrete flood control channels that bear little resemblance
to natural creeks. Still, these altered creeks define your watershed.
The best tool for discovering
your local watershed, and your place in it, is the umbrella. On a rainy
day, start on your front steps, follow the rainwater down across the sidewalk
and into the gutter. Which way is the water running? Follow it. Soon you
will come to a storm drain. This is where the game gets interesting. Maybe
the water just flows back out of a storm drain across the intersection,
or maybe it falls into a culvert. Watch out for traffic, and peek down
the drain with a flashlight; which way does the water run? Look around;
is there an apparent downhill? That is probably the direction the culvert
runs, typically under a street. Follow it and listen at each storm drain
for the sound of water. Follow the sound. Remember that you are following
a storm drain, not a sanitary sewer. Look for manhole covers that say "storm
drain," not "sewer"--unless you are in San Francisco, or parts of Sacramento,
where the two are combined. With skill, and some luck, you will find the
point where the storm drain spills into a creek. The creek's name is frequently
stenciled on the bridge where the road crosses it. The name of that creek
is the name of your watershed.
In hilly areas, simply walking
downhill is a reliable way to find your local creek--the creeks are in
the bottoms of the canyons or valleys. But if you live in a flatter area,
such as the flatlands of Berkeley or along the floors of the San Fernando
and San Gabriel Valleys, you may get fooled. In these areas the creeks
have built natural levees and actually run across the high points on the
landscape.
Now find the divide surrounding
your watershed. It will be a high point, although in flatlands the difference
in elevation may be barely visible. Back at the gutter, walk upstream from
your house. Eventually you will come to a spot where the water pools in
the gutter. Farther still, the water in the gutter begins to flow in the
opposite direction; there, you've crossed your watershed boundary.
Now you will understand where
you are in relation to the land and water immediately around you. It's
only the first step, for your little watershed is part of a bigger watershed,
and so on. But at this point you may understand a few things that may have
mystified you earlier: why water flows through a neighbor's basement every
winter, for instance. That neighbor's house may be standing over a culverted
creek, or just uphill from one, in the path of groundwater flowing toward
the former creek. Ironically, an open creek might have drained this groundwater--the
culvert may be preventing that drainage.
The umbrella is the best tool
in your watershed quest, but it's by no means the only one. Look for a
line of trees--in Spanish, an alameda. Alameda County was named
for the rows of trees that followed the creeks from the East Bay hills,
proceeding across the flatlands and down to San Francisco Bay. Many of
these rows of trees still cut across the urban landscape, even where the
creeks are today buried in culverts. In northern California these trees
are frequently maples, redwoods, eucalyptus, and willows; in southern California
look for sycamores, cottonwoods, and willows.
There are other clues you can
look for. Traveling along many large suburban boulevards, you may be crossing
creeks, or the flood control channels they have become, without ever noticing,
for the crossings do not look much like bridges. But if you see short stretches
of matching high-security fencing on opposite sides of the street, that's
a clue. Such fencing is frequently erected to discourage junior hydrologists
from chasing water striders in what remains of the creek flowing under
the road.
Maps are a great help, of course.
Several types are useful. California State Automobile Association maps
do a good job of showing remaining urban creeks in northern California,
but sadly, the same is not true in southern California. Even the northern
California maps are not without oddities, such as creeks and roads "rerouted"
around the map legend or street index. The U.S. Geological Survey topographic
maps are great, especially in less developed areas. Creeks are clearly
marked, as are the ridgecrest divides between watersheds. But topo maps
are often out of date because, typically, the urban landscape has been
altered since the map was produced. Take a blue marker and highlight the
fine blue lines that represent creeks on the map showing your neighborhood.
Then walk around double-checking what they show. You'll probably find lots
of differences.
If the map you are using shows
few actual creeks, still other clues await you. A street that wiggles across
the map with little alignment to the local street grid may be built over
or alongside a culvert laid in a creek. Glendale Boulevard, Laurel Canyon,
and the Pasadena Freeway in the Los Angeles area are all good examples,
as is 14th Avenue in Oakland.
To get a detailed picture of
the storm drain and creek system in a region, you need the storm drain
maps from city and county public works departments. These maps show block-by-block
detail of storm drains, and usually the creeks as well. However, even if
your local agency has done a good job of mapping, the maps may be incomplete.
Most agencies record only culverts they build themselves or for which they
issue permits to contractors. Culverts built without permits seldom appear
on these maps. Sometimes culverts that were not built show up on the map
because a permit was issued. Where creeks are the border between counties,
culverts may not be recorded by either county.
Another great resource is old
maps. They often show the creeks before your neighborhood was built. Central
libraries and university libraries often have map rooms or history rooms
with maps of the Spanish land grants, government survey maps from the 1850s,
or real estate maps from the turn of the century. Aerial photos may be
available as well. These are all treasure troves, rich sources of further
information to help you understand your watershed.
Locating your creek and watershed
in an urban environment can be a challenging task, but it can be eye opening.
If you're lucky, you may live in an area where someone has published detailed
creek and watershed maps. These are great tools for your quest, but they
are no substitute for actually going out with your umbrella to follow your
runoff. You will see how this water, hidden and confined, still nourishes
plants and wildlife, and come to appreciate the direct connection between
your home and the natural world.
Christopher M. Richard is curator of aquatic biology at the Oakland Museum of California. Janet M. Sowers is a geologist at Lettis & Associates, a consulting firm in Walnut Creek. |
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