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The Dry Garden: Capturing the spirit of L.A.'s streams, even if they're gone

December 11, 2009 |  9:45 am

GreenStreamMap
When it snows in the mountains and rains in the basin, Jessica Hall thinks of the lost streams of Los Angeles. In fact, she thinks of them all the time. For the last nine years, the 41-year-old garden designer has been retracing the paths of the native creeks, streams and springs that once ran wild before they were filled in and paved for homes.

In the process, Hall has come to believe that the best town planning and landscape design principles for the future may lie in understanding the habits of the watercourses of the past.

Those who missed the profile of Hall last August by Times staff writer Hector Tobar have a treat in store reading about how Hall tracked down Sacatela Creek, a jewel of a waterway that once flowed from what is now the Shakespeare Bridge in Franklin Hills to the Ambassador Hotel in mid-Wilshire. If Los Angeles ever wakes up to the potential of “daylighting” lost waterways, Hall will have been part of the story.

But this column picks up where the Tobar article left off, in particular to ask: What has this Princeton architecture graduate learned chasing streams that may be applied to capturing storm water at home and making the good choices when designing a garden?

The first, most basic answer can be found in a study of the vast Ballona Creek watershed. Hall and three other students produced the study as she was earning a master's degree in landscape architecture at Cal Poly Pomona.

 “Seeking Streams” shows how rain and snow etched the landscape of Southern California before we arrived with earthmovers and asphalt. Snowmelt and rainwater cascading off the foothills deposited the characteristic soils, then shaped what grew.

Although those streams are largely gone above ground, their impact is alive and well below the soil line in underground waterways, Hall says.

So for Hall, one of the most basic steps in garden design is to revisit the basic plant communities that were first defined by streams.

GreenPlantCommunities
They are: coastal sage scrub, which occurred on drier, low-elevation sites; chaparral, on hillsides and north-facing slopes; coast live oak woodland in the upland areas, north slopes, foothill canyons, shaded ravines and canyon bottoms with well-drained soils; foothill riparian woodland; coastal riparian woodland; and freshwater marsh or cienega.

GreenClayHands Each of these plant communities had distinct soil profiles, which Hall’s group also studied and classified. Determining soil type, Hall says, requires one tool: your hand. “If you take it in your hand and it forms a sticky clump, you know you have clay soil. If it is crumbly, you have loam or sandy loam.”

As she considers how to plant a property, she looks at how water -- be it rain or from a hose -- will behave on the site. Smart landscape design will protect the home while harnessing the water, capturing it wherever possible.

For homes on steep hillsides, Hall urges care in water trapping. “Keeping water on your property is the appropriate thing to do when you have soil that will absorb it,” she says.

In Los Angeles, when it rains, it so often pours. No matter how many rain barrels we put out and percolation pits we dig, many homeowners can do only so much in compensating for the absorptive and cleansing power of lost streams. Because many sites cannot capture all the rain that falls on them or flows through them, Hall sees cleverly situated public water-catching projects as crucial companion pieces to the water gardens put in by homeowners.

Asked to point one out, Hall chose the Bimini Slough Ecology Park. Designed by city landscape architect and wastewater engineer Nishith Dhandha, this mere half-acre sandwiched next to the Breese Community Center in Koreatown acts as a giant filter by taking urban runoff from a full city block. First it captures the water, then passes it through grates to catch trash. From there, the storm water runs through a meandering marsh, where riparian plants do what they have always done: cleanse the water.

The urban storm-water filter doubles as a park.

Put these elements together – appropriate landscaping around homes and businesses, then public projects to trap and filter urban runoff – and Hall sees two simple, elegant landscape design solutions returning the lost benefits of streams to Los Angeles.

As our rainy season begins in earnest, explore landscape projects like these in more detail and follow L.A.’s stream seekers. Check out the website, L.A. Creek Freak, that Hall co-publishes with local artist Joe Linton. Also consider bookmarking the California Department of Conservation Watershed Program, the Los Angeles and San Gabriel Rivers Watershed Council, Friends of Ballona Wetlands and the Malibu Creek Watershed Council. For more information about Cal Poly Pomona's 606 Studio program, which promotes the preservation and restoration of sensitive ecological systems, click here.

-- Emily Green

Green's column on sustainable gardening appears here weekly. She also blogs on water issues at www.chanceofrain.com.

Watershed map and plant communities illustration from "Seeking Streams" by Brian Braa, Jessica Hall, Chiung-Chen Lian and Greg McCollum; clay hands photo by Emily Green.

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