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

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.

 
Comments () | Archives (9)

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Absolutely fascinating! I'm off to see the Koreatown water utilization feature
Emily Green describes. I am a total fan of everything she writes. Go, Emily!

This is awesome!!! I wish her next project would be the 150 sq. mile watershed that drains into Newport's Upper Back Bay a little further South - very similar issues. The wetlands all this water dumps into are some of the very last remaining estuaries in Southern California - vital to the migratory bird path and many native species. The channeling of the water has caused many issues like sediment deposit, chemical pollutants, trash, etc. disrupting an already fragile system. It would be fascinating to retrace the paths and tributaries of the Santa Ana River and plan landscaping accordingly, especially where developers are concerned...

Great article! As I sit here listening to rain drops hitting my roof, I realize that we should be doing more as individuals and communities to capture and utilize the natural flow of water that would otherwise flow through storm drains and out to the ocean. This is becoming an increasingly critical issue and we need to start acting now.

Thanks to Jessica, another public water-catching project/park may be built in the Ballona Watershed. In November, the Los Angeles City Council included Expo Greenway among several "best management" concepts to help meet federal Clean Water Act standards for Ballona Creek. (http://ExpoGreenway.org; http://www.lastormwater.org/Siteorg/program/TMDLs/tmdl_ballona_bacteria.htm)

Good reporting of a topic that readers can actually use to make a difference. Soil classification is not new knowledge but it seems not very many people know about it or know how to use it. Rain falls freely, most landscape irrigation is costly. When are we going to stop wasting our water? -- It good to know Hall'a group at CalPoly is pursuing water issues. Please continue publishing what you learn. Thank you for the links.

Great article, Emily, and great work, Jessica. One of things that concerns me about many landscape projects that seek to capture rainwater is the concept of burying large plastic cisterns. Does Nishith's Bimini project include this or is it just boulders and grading?

Also, Jessica, what about grasslands in the flat parts of So Cal? Maybe needle grasses with a few sages but not quite sagescrub? Just wondering.

Thanks for writing this article! I'm really impressed by the visionary work of Jessica and others working on stream restoration in LA and am excited about the possiblity of people transforming their front and back yards into restored habitats.

I have to agree with these comments. I also think that the single greatest improvement to any SoCal neighborhood would be a meandering streambed full of trees, paths and wildlife. We fence them off from the public here in Huntington Beach. There is a plan to divert the urban runoff into a marsh, but it is going nowhere.

Hi everyone and thanks for the comments and kind words!

Re: Newport Back Bay, I believe there's lots of planning going on to treat the runoff. It may take a while but it's a protected waterbody under the Clean Water Act so we'll be seeing improvements over time. In fact, the upstream Irvine Ranch Water District was one of the first in our area to create a treatment wetland-the San Joaquin Marsh - taking water out of San Diego Creek to clean it up using microbes and the natural filtration of plants and soil. IRWD has plans to increase treatment all up the creek.

These solutions are great for the dry-weather flows. But our So Cal storms are flashy - a big rain is difficult to treat. And as we all know, we lose most of what could be plumping our aquifers to the stormdrains and oceans - one of the reasons I'm a fan of pulling up paving wherever it makes sense, keeping roads and parking lots to a minimum and - to go out on a limb - re-establish functioning floodplains. These actions increase percolation to our groundwater, reduce pollutants, and in the latter case, increase habitat and open space.

Nishith reported back that plastic cisterns are not used at the Bimini project, and I like the idea, Barbara, of re-establishing our native grasslands, especially the needlegrasses and other historically local species. The wildflowers that associated with these grasslands were incredible! I don't think the answer is to create wetlands or fake streams everywhere - that's a disneyland approach to our landscape - what I find enriching is the idea that our basin is made up of unique and varied habitats, and our soils tell us some of the story of this, and we can work appropriately with those habitats to achieve our stormwater management & water supply goals. Historical ecologists such as the folks out of the San Francisco Estuary Institute, Shawna Dark at CSUN, Travis Longcore at USC and Erik Stein out of the Southern California Coastal Waters Research Project are uncovering amazing descriptions of the flora that was Los Angeles - and that can serve as a template to reconnect us with a sense of place that goes back centuries.

But back to the grasslands - they are not only an endangered habitat, but their deep root-systems create pathways to aid in infiltration, as do the roots of many of our chaparral and coastal sage scrub communities. I learned that their are clumps of needlegrass in the central valley that are over 100 years old! What an amazing plant we paved over.

OK, folks, I've been long-winded here but I am happy to keep the discussion going.


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