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Sun Valley, a community in the San Fernando Valley, is one of the many suburbs in the city of Los Angeles. Like the rest of Southern California, it lies in a semi-arid climate zone, where the average rainfall is only about 12 inches a year. Water has always been an issue in this region.
Sun Valley was established in the 1800s; it lies at the base of the Verdugo Mountains. It is prone to flash floods, and, for reasons that I can’t seem to explain, the city was built without storm drains. It has long suffered serious flooding problems.
As the city grew, streets and roadways were paved and before you knew it, hard pavement covered much of the community. Unfortunately, whenever it rained, the rainwater had no place to go. It just ran down the streets, picking up debris along the way. By the time it finally got to a storm drain, the rainwater was completely contaminated and the debris that came with it would clog what few storm drains there were.
To give you an idea of how bad it was, anytime TV news crews needed to shoot footage of flooded intersections, they headed straight to Sun Valley.
The Sun Valley Watershed Stakeholders Group examined the chronic flooding and developed a plan: to solve the local flooding problem while retaining all stormwater runoff from the watershed; to increase water conservation, recreational opportunities, and wildlife habitat while reducing stormwater pollution. The devised sustainable solutions are all a part of the Sun Valley Watershed Management Project.
With the help of the TreePeople organization in Beverly Hills, California, working in partnership with the Los Angeles County Department of Public Works, the city of Los Angeles and other local stakeholders, they created and implemented green solutions to harvest rain and floodwater, while addressing an antiquated infrastructure.
What makes the project unique is that it offers a single integrated plan that addresses flood protection, water quality and water conservation in its 2,700-acre watershed.
The Sun Valley Project includes rain gardens, sunken areas in the landscapes to capture rainwater from roofs and other impervious surfaces. Also included are vegetated bioswales—creek-like, constructed wetlands that create a wildlife habitats while cleaning stormwater runoff via natural processes, and trees planted with mulched root zones, so that the water runoff is filtered and infiltrated into the aquifer.
Moderate-sized rain tanks were installed around homes, as well as giant underground cisterns under schoolyards, parks and wildlife areas. These new, sustainable features enable the community to treat stormwater and redirect it to two large infiltration basins where the water is naturally filtered before ultimately recharging the aquifer.
The large basins do their work silently, out of sight, while soccer and softball players play on the fields above. Streets have been retrofitted with a variety of rainwater harvesting techniques that filter water back into the ground. Infiltration galleries beneath the street are designed to provide 16 acre-feet of groundwater recharge annually. This is about the same amount of water that is used by 30 households annually.
Rainwater harvesting utilizes a collection system to gather rainwater and use it for outdoor purposes.
It’s also good for the environment, because it places less pressure on the water distribution system, particularly where water supplies are tight.
Instead of installing storm drains to channel rainwater to the ocean, one city block now catches, cleans, and reuses rain and stormwater from a 40-acre area upstream.
The project also increases wildlife habitat and community access to green space. Community enhancements, like new sidewalks and solar-powered street lights, were installed to make the neighborhood safer and more conducive to walking. Educational signage was another important feature of the multiuse project.
“The residents are now the watershed managers,” says Rebecca Drayse, former director of TreePeople’s Natural Urban Systems Group. “Their properties and the street are literally interconnected, mimicking the natural hydrology of the Los Angeles River Watershed, which has been so greatly impacted by development for the past century.”
An unexpected outcome from the project is that the residents have experienced an increased sense of community and place as they’ve gathered to plant trees and care for their new landscape.
But probably the most innovative component of the plan involves its advanced water capture system, which uses both natural and engineered technologies that mimic and even improve on the original watershed.
Fortunately, the city no longer allows rainwater to escape, flooding intersections and rushing down streets. The new neighborhood brings value to its environment and community by capturing the water, cleaning the air, healing the soil, and reducing its impact on the surrounding land and the ocean. It’s a neighborhood that can better adapt to climate change, be resilient to droughts and flooding, and offer a healthier and more beautiful place to live.
Could the methods of Sun Valley be expanded to serve other cities? Absolutely. Drier regions, especially areas that are in arid or semi-arid areas, such as Texas, Arizona and California, can’t afford to waste one more drop. The need is clear; the technology is available and the potential impact will be significant.
If we can learn to effectively harvest and recycle the drops that fall to the earth when it rains, and use that rain to help water the landscape, we can cut down on our use of potable water.
Harvesting rainwater could be the first step toward making a difference between a water-starved state and a water-sufficient one. We have the power to alleviate some of our cities’ water problems with a resource most states currently squander and be eco-green in the process.
We can no longer ignore the current data, which clearly points to our water sources being threatened and finite. It’s in our best interest to start finding sustainable, eco-green solutions to address this looming problem.
So, the next time it rains…look up and be thankful.