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Innovative ideas for Southern California: Practical projects and techniques show how stormwater and ‘urban slobber’ can be a valuable resource for our region

Posted by: Maven on September 15, 2008 at 6:28 am

“It never rains in California” is just a line in a song, for anyone who has lived in Southern California for a while knows that while you won’t have to scrape your windshield on a frosty morning and you can wear shorts and sandals to do your Christmas shopping, you will need an umbrella occasionally as well. And while a rainstorm might be good news for air quality and perhaps even give you a free car wash, stormwater and urban “slobber” – that steady stream of water that accumulates in the storm drains due to over-irrigation of landscapes and whatever else – represents a significant source of water pollution in Southern California.

Municipal codes in the past have directed that developed areas direct storm water and urban runoff into storm drains, which were designed to drain areas quickly and prevent flooding by directing the runoff to the nearest stream or river and eventually the ocean. Water directed into these drains picks up trash, pesticides, fertilizers, heavy metals, bacteria and construction waste on its way downstream, where it is eventually dumped, untreated, into the ocean. This polluted urban runoff contaminates local waterways and closes beaches for days in its wake.

It has been estimated that in Southern California, over 500,000 acre-feet per year of rain water and urban runoff flows out to the ocean. Stormwater and urban runoff is a major problem, but what if that water could be put to good use?

Studies have shown that in an undeveloped area, half of the rainfall will seep into aquifers with as little as 10 percent making its way to local waterways. However, as more impervious surface is added by development, about 55% of the water will end up in local waterways, while the amount that percolates into the aquifer to replenish it is reduced to as little as 5%.

Just one inch of rain falling over a paved area one acre in size produces 27,000 gallons of water. By finding ways to retain this water and allow it to infiltrate into local aquifers, a ‘new’ source of water can be developed and utilized.

“Low Impact Development” methods work to infiltrate, filter and store storm water by creating bioretention facilities both on the property and within the community. These are areas of soil, grasses, shrubs and small trees where runoff from impervious surfaces is collected and allowed to undergo natural treatment and to percolate into the local aquifers. This also creates an opportunity to create valuable wildlife habitats while simultaneously preventing downstream pollution of waterways and beaches. Permeable pavement, cisterns, green roofs, and vegetated swales can also be used to reduce urban runoff and increase groundwater infiltration.

For more information on Low Impact Development:

But what about existing developed areas? Even though much of Southern California is intensely developed, with nearly all the storm drains and rivers now paved concrete conduits flowing straight to the ocean, innovative projects such as the Augustus Hawkins Nature Park and the Tujunga Wash Greenway project are redirecting storm water and urban runoff into created natural areas that recharge local aquifers and reduce the amount of water dumped into local waterways. They also serve as valuable wildlife habitat as well as creating park-like areas the local communities can enjoy.

The Tujunga Wash Greenway project, pictured at the right, is a joint project between the County of Los Angeles and the Santa Monica Mountains Conservancy. During an average year of rainfall, as much as 325,000 gallons a day will flow through the mile-long artificially-created streambed, which will provide enough groundwater recharge to supply 760 families of 4 with drinking water for an entire year. Benches and interpretive plaques line the pathway, providing open-space and a recreational amenity to the local community.

“The Tujunga Wash Greenway and Stream Restoration Project provides an innovative solution to regional water quality and supply challenges, while restoring natural habitat and bringing
parkland to the urban core. It is a model that can be replicated throughout Southern California,” said Joseph T. Edmiston, executive director of the Santa Monica Mountains Conservancy.

The Los Angeles and San Gabriel Rivers Watershed Council said in its 2005 Report: “On average, over 500,000 acre-feet of runoff flow to the ocean from the Los Angeles County basin each year. If some portion of this water can be captured for reuse, the pressure on supplies in northern and central California may be moderated”.

For more information:

Another group, TreePeople, long ago saw the misuse and loss of resources in the conventional management of cities; however, in 1994 when they launched their project, the government agencies were not practicing integrated urban watershed management, and multipurpose projects to better manage and utilize stormwater resources were considered neither feasible or necessary. Instead of conducting studies to try to influence them, TreePeople instead constructed projects that demonstrated the practicality and benefits of controlling urban runoff, allowing agency staff, policymakers and the public to see them in action and imagine them implemented on a city-wide scale.

Through strategically planting trees, capturing and retaining stormwater on site, groundwater sources are replenished and downstream pollution is reduced. To date, the organization has successfully implemented a number of projects which demonstrate alternative stormwater management approaches and practices. In the report, Rainwater as a Resource, they detail three of their projects: one single-family home project and two projects implemented at Los Angeles area schools.

The TreePeople continue to innovate and refine their ideas and projects while continuing to advocate for their adoption with local agencies. “The opportunity exists for us to reduce water importation significantly, prevent water pollution and flooding through increased onsite retention, reduce landfill volumes considerably and create employment opportunities – all while improving the quality of life of our communities and ecosystems.” (Rainwater as a Resource)

For more information on TreePeople:

September 15, 2008 · Filed Under Water Quality

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