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After the Lawn: Transitioning to an Integrated Rain Garden

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Roads as Rivers
Here a schematic of our test case street (minus trees) shows the original basic compliment of lawn and pavement across Southern California. Under this system, lawn is watered by imported potable water while gutters, driveways, streets, and stormdrains discharge local rain into the Pacific.

California has been told by Governor Brown to reduce its water use by 25%. The Mayor of Los Angeles wants the largest city in the state to cut imports of freshwater by 50% in the next nine years. We can expect a lot of these cuts to be made in garden irrigation supplies because, to paraphrase Willie Sutton, "that's where the water is."

The good news? We have local water to replace at least some, if not all, of the irrigation that will be lost. As calculated in Part Seven of this series, even in this light rain year, a conventionally designed 1,200-square-foot house on a 5,000-square-foot lot would have shed enough fresh water to the street to meet the average use for an Angeleno for three months.

Southern California, behold our new irrigation supply. The trick is capturing it.

Part Six of this series illustrated how a single rain barrel and hose might capture the run-off from the front roof of our case study home. Add barrels to downspouts for the side and back roofs and garage, and the imaginary house would have drained almost 8,000 gallons of fresh water to the garden, in even this 9-inch rain year. Break up the sidewalk and add simple infiltration galleries to the driveway, and there's another 4,000 or so gallons to be caught that might have otherwise run off the lot's concrete driveway and front walk. To ensure that all this water then percolates into the ground, which is where it does the most good, the next step is creating what has become known as a "rain garden."

Simply defined, a rain garden is a landscape that has been altered to stop outflow of rain to the street. If you attend this year's Mar Vista's Green Garden Showcase or went to the Theodore Payne Foundation tour in March, you will see (or have seen) basic models. Parts of the yard, usually the front, are reshaped to function like a miniature watershed from the mountain peak (roof) to terminal lake (the trough you've dug) maybe 20 or 30 feet away in the front yard. Typically sweet and simple ones consist of ribbons of river rock set in troughs fed by a gutter downspout. Rain gardens can be sharply modern or rustic, concealed or integrated into the design, however all of them have one thing in common. The water enters at a grade higher than where it settles with an over-flow outlet to the street to prevent back-up near structures.

Not every site is suitable. My first rain garden, inspired by the Garden/Garden prototype in Santa Monica and built in 2004 by the then-UC Berkeley landscape architecture masters candidate Marco Barrantes, was on a relatively flat central Los Angeles lot. Constructed out of a mix of concrete salvaged from removal of a redundant driveway and front walk, Barrantes created a mock arroyo worthy of Lummis House that drained roof water to street trees. The system that Marco built now supports three coast live oaks that shade pedestrians and cars in afternoons along with a lazy splay of manzanita and native lilac. It should require supplemental water only in the dog days of August, September and October.

My second water-catching system could never evolve into a pure rain garden. Set high in the foothills near the Angeles National Forest, site soil of fast-draining sandy loam meant that concentrated infiltration of water into the ground anywhere near the house might compromise an aging retaining wall and even flood the downslope neighbor's basement. After paying a string of experts to be told what I didn't want to hear, I settled for barrels. To see whether or not your site is suitable to infiltrate rain, TreePeople offers excellent resources and classes. The City of Los Angeles has a very good guide and, perhaps best of all, be sure to read the free online rainwater harvesting handbook by Washington State University.

Pasadena Rain Garden
This stand alone rain garden in Pasadena bristled with admirers on the Theodore Payne Foundation tour several years ago. Imagine if every house on the block produced the same splay of flowers and supported healthy street trees using little more than smart infiltration of seasonal rain.

And so to cost. Unlike a barrel-and-hose set-up, rain gardens are not necessarily cheap or easy to install. After checking with the city where any utility lines serving the property might be buried, as described in Part Seven, anyone attempting curb cuts needs to get permits to access street water. Then there are consultation fees with a landscape architect to set safe grading and drainage specifications. More checks will be required to pay the arborist who should direct work around any mature tree. The team doing the concrete work won't be free. By the time the truck from the landscape supply house pulls up with river rock and mulch, you would be getting away cheaply for a grand for a simple rain garden. Go for the pavement breaking and land-shaping suggested in the drawings and, including new plants, the cost would swiftly rise to closer to three or four thousand dollars.

And that's only installation. Where water flows over unpaved land, seasonal weeds will follow. Only weekly patrolling in rainy season by a keen home gardener or skilled maintenance team would keep it looking good. You can't mow an arroyo.

Driveway Pebbles
The Mar Vista Green Garden Showcase and Los Angeles Beautification Team advocate cutting infiltration galleries in concrete driveways then filling them with pebbles to slow run-off of seasonal rains and refresh groundwater to serve gardens. | Photo by Emily Green

Myself, I'm in, but many people don't do much more in their front gardens than pass by it as they go to their car. It's no mystery why so many Southern Californians are simply calling Turf Terminators and having their front lawns turned into gravel yards with a smattering of notionally xeric plants stranded among the rock. But, before Turf Terminators, which is advised by former executives of the Metropolitan Water District, which in turn administrates the Southland's rebate program, banks your cash-for-grass check, please ask yourself a few questions: Who benefits from what the company describes as a "free" job? What exactly are you killing? Your lawn or your property value? What will a sudden conversion from lawn to gravel look like? What about radiant heat from the rock? What will your air conditioning bill be? What happens when weeds recur in the rock, which they will, even over weed cloth? What about irrigation to street trees? What about our Los Angeles suddenly feeling like Las Vegas? Answer those questions and putting three or four grand toward a rain garden can suddenly sound cheap.

But before you do this, look up and down the block again, then ask, "What about a rain street?" Rain gardens applied on a block-by-block level offer both economy of scale and wildly enhanced beauty. Behold green streets such as the TreePeople-Council for Watershed Health collaboration on the Elmer Avenue Project in Sun Valley, or whole green blocks such as Seattle's Broadview Green Grid and the potential is stirring. The $2.7 million price tag, alas, can leave you shaken, not stirred. However, watershed council programs director Mike Antos warns that the Elmer Avenue budget includes a lot of things that weren't rain-related such as solar street lights. He's working with USC to "unpack" the costs to give the city baseline estimates for stormwater street retrofitting.

By way of new legislation that might encourage whole block conversions, Antos points to revised stormwater management guidelines now moving through committee at the Los Angeles City Council. If passed, these could require often dysfunctional city agencies such as sanitation and transportation to include rain capture in any road work for the City of Los Angeles. Read the federal Environmental Protection Agency's "Stormwater to Street Trees" and it becomes clear that no street work in any American city should go forward without stormwater being diverted to urban canopies.

This schematic shows the test case house from this series evolved over an estimated five years from a lawn and lavender mix to fully-fledged rain garden.
This schematic shows the test case house from this series evolved over an estimated five years from a lawn and lavender mix to fully-fledged rain garden.

In a perfect world, every community would have a local equivalent of the Los Angeles Beautification Team, a non-profit working in Hollywood and the San Fernando Valley, that will move in and help homeowners, schools and communities devise and install affordable, doable rain gardens. In this world, for those outside of LABT's service area, my advice is this: Save water smartly and plan for the future. Allow your turf to become dormant or put in the simple kind of rebate gardens as described in Parts Two through Six of this series.

Concentrate what water you are allowed through ordinances and can capture through rain barrels to irrigate high value street trees. As you do this, go to your neighbors or block club. Find out who else might be interested in a watershed approach for your block. Generate drawings. KCET is publishing my drawings not because they're professional-looking but precisely because they're the work of a rank amateur. If a 59-year-old lady who hasn't taken an art class since the 9th grade can do them, chances are good you can too. Go to a non-profit such as TreePeople for classes and the Theodore Payne Foundation for advice on what kind of plants could eventually be expected to flourish on a rain garden budget in your area. Once you have a plan, march it into your council district field office or, if you're in an unincorporated city, take it to a County Supervisor. Ask for money. If you don't get that, ask for goods-in-kind and free labor from the Conservation Corps and UC Master Gardener Program. Go to your water company and ask for a special rebate.

Drought doesn't have to mean dismal when there are rivers running right past our front yards. Most rain years, there is clearly adequate local water falling on our roofs and rolling down our streets to supply our front yards. It's up to us if we will catch it.

Next installment: Grey(water) Gardens. In praise of outdoor showers and other diversions of inside water to irrigate backyards.

Follow the entire After the Lawn series:
After the Lawn: Part I
Designing Your New Garden
Caring For Your Turf
How to Remove Your Lawn
Planning Your New Garden
How to Design Your New Garden
Managing the Parkway

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