BILL O'BRIEN

Meanwhile, not coincidentally, growing numbers of citizens are getting to know their local creeks and watching over the shoulders of those who seek and issue permits that can either destroy or protect them. First, however, they must find their creeks.

CHRISTOPHER RICHARD, JANET SOWERS, AND I are searching for a creek. But we're not, as you might expect, scrambling over boulders, slogging through the mud, or negotiating our way through dense underbrush. Instead, we're cruising along on Interstate 580 just a few miles south of Oakland toward the city of Castro Valley. We exit onto busy Redwood Road, turn left onto Fourth Street, then drive through a neighborhood of one- and two-story homes, past Lucky Cleaners and Quart House Liquors, and onto Sparks Way, a cul-de-sac.
What we're looking for is a very small stream, a tributary of Castro Valley Creek, itself an offshoot of San Lorenzo Creek, which flows from the East Bay hills to San Francisco Bay. This creek could be dried up in some places, barely flowing in others. Richard and Sowers are putting the finishing touches on a project for the Oakland Museum of California, a map depicting the creeks and watersheds of Hayward and San Leandro. Most of the work has been done, but Richard, the museum's curator of aquatic biology, and Sowers, a geologist consultant, are filling in the fine print--or in this case, a very slender blue line on the final map.
Sowers has studied this area pretty thoroughly, using maps from the U.S. Geological Survey (USGS) and the San Francisco Estuary Institute, among others. The maps seem to indicate that there is a creek here, but the section we're looking for has been encased in a culvert, or routed into an open concrete channel. Sowers, however, has a hunch that at least part of the stream might still be in a more or less natural state.
We're still not sure exactly where the creek is, however. As we turn onto the side street, Sowers stares intently at a topo-graphic map and tells Richard, "If there's a dip in the road, then this is the right place." Sure enough, there is, so we stop the car, get out, and head for a storm drain. The two researchers cock their ears to the grate and hear a faint trickle of water. We peer over a nearby fence into someone's backyard, where Richard spots trees and undergrowth typical of a riparian habitat. "There's a creek down there," he says. What shape it's in, though, we can't tell.
We wander up and down the street. No one seems to be home. We stretch tall to see over the fences, but the water is just too far away. Sowers sighs. "This is where the difficulty comes in when you're mapping urban creeks," she says. "It's always tough when you can't get access to see things." Gazing over fences into people's backyards can make neighbors suspicious. "Sometimes I take a hard hat with me," she says with a chuckle. "It makes me look kind of official."
Just down the street is a small park, but we still can't get close enough to complete our inspection. "It's a creek, anyway," Sowers says. "Whether it's in concrete or not, I don't know." As we ponder what to do next, a car pulls into the driveway of one of the homes bordering the creek. Richard goes up to the house and explains our mission.
"Want to go down and look at it?" a friendly gent asks, then leads us back around the house. In a moment we are scrambling through bushes, over boulders, and around the tall eucalyptus trees that line the muddy creekbed. We pass the remnants of some ancient machinery--a pump perhaps--next to a rustic-looking barn-red dilapidated shed.
There's hardly any water in the creek now, but our host says that in the winter this trickle quickly swells. Though no nearby homes have been damaged by the creek, he tells us, "It can get really crazy down here." The stream, he adds, is called Deer Creek. Deer regularly browse on the thick vegetation.
We reach a point where the creek disappears into a tangle of blackberry brambles that have grown over sand washed down and deposited here. It's nearly impossible to continue, so we head back to the street, thank our host, and move on. "We lucked out," Sowers says, then turns to Richard: "Well, Chris, I think I'm going to have to change something." The final draft of the map will show a solid blue line for Deer Creek, indicating that it is above ground and unchanneled here. The line will replace a series of dots that had been penciled in to indicate an underground culvert.
The Hayward/San Leandro map is the second in a series by the Oakland Museum. The first, showing creeks in Oakland and Berkeley, was issued in 1993 and updated last year. Work on a map of Fremont is under way. The mapping project grew out of a desire to reach beyond the museum walls with ideas that originated in the Aquatic California Gallery. Richard had overseen the creation of that project, which features a large wall chart showing the entire creek system of the East Bay. The printed maps are much more detailed, with creeks overlaid on a street grid and bands of color to show different watersheds. Sowers's firm drew the maps for the museum. Financial support has come from the Alameda County Flood Control District, which saw the maps as tools for public education and to help meet federal water quality requirements for control of nonpoint source pollution.
Among those using the maps are teachers and people involved in creek restoration. "We take them to all our meetings," says Brenda Chatfield, education program coordinator for the San Francisco Estuary Institute, who has helped to set up watershed awareness programs in Oakland and San Leandro. "We have used them to describe what a watershed is and where a watershed is." Learning about their creeks and watersheds "gives people a connection with the environment other than just their streets," she explains. That in turn can lead them to realize that dumping oil down a storm drain or spraying their garden with a heavy dose of pesticide has far-reaching repercussions. "That's a big plus in trying to reduce urban runoff pollution." Looking at the maps, some people have discovered that they're living right near a creek, Chatfield says. "Then they say to themselves, 'Maybe that's where the raccoons cutting through my backyard are coming from.'"
The researchers used many tools in creating the urban creek maps, including USGS maps, city and county flood control maps, aerial photographs, and historical maps.
In the hills, it's generally pretty obvious where a stream is, or at least was. On a topographic map, too, a creek seeker can see: "There's a hill here, there's a hill there, so there must have been a creek in between," Sowers says. Down in the flatlands it's a more complex task--researchers must find clues on the maps, such as small ridges that indicate traces of natural levees on the alluvial fan. Richard notes that slow-flowing flatland creeks sometimes actually build up their own sedimentary ridges, then shift their courses to nearby lower ground as a result of earthquakes, flooding, or some other occurrence.
Determining watershed boundaries can also be difficult. In addition to studying the ridgelines on the topo maps, they've found the storm drain maps kept by local flood control agencies to be particularly useful. Storm drains generally flow into creeks, and by studying the maps a person can determine which way water is flowing. But the accuracy of the maps Richard and Sowers used in their project could never be taken for granted. That's one reason they do what they call "ground truthing": going to different sites to see what's really there. "I visit as many open sections of creeks as I can," Sowers says. "Then I sit down with my colored pencil, trying to make sure everything connects."
The East Bay is crisscrossed by hundreds of creeks, and there are uncounted numbers of streams flowing through, or under, San Francisco, Los Angeles, and virtually every other city on the California coast. City dwellers only see the tiny bits of a creek that haven't been encased in concrete, says Sowers, so it's very difficult for them to envision a whole stream from its source to its mouth, and even harder for them to picture an entire watershed.
"With the maps, people can see there is a whole stream system. If you can find your house on a map you can tell what watershed you live in."

Bill O'Brien, a freelance writer, lives in Berkeley.
A revised version of the Guide to East Bay Creeks, published as a companion to the map series, is now available. The book, edited by Richard, contains chapters about the ecology and history of urban waterways, five "walking tours," and a resource list for people interested in creek preservation and restoration. See www.museumca.org/creeks.