Low Impact Development Will Help California and the Arid West Retain Rainfall

The good news is that in June, water use in Los Angeles fell to a 32 year low for the time of year, a remarkable savings considering the steady population growth the region has seen over that period.  The bad news is that the reductions were spurred on by drought conditions that are gripping California for the third year in a row, and that drought, and the effects of global warming we are only just beginning to feel, severely threaten our remaining water supplies.  Thankfully, an emerging land use planning and stormwater management design approach called Low Impact Development, or "LID," may hold the key to increasing the local, stable, supply of water in California, while at the same time reducing global warming pollution and the effects of climate change in the state.  Even better, LID can provide these benefits at bargain prices.

Californians have a curious relationship with water.  When it rains, which despite the semi-arid climate present throughout much of California it does in great rushes, we take the water and channel it into concrete and metal pipes and dispose of it as fast as we can - directing it from the unending hardscape we've paved over the ground with into gutters and storm drains to wash it, and a flood of pollutants it picks up along the way, down to the ocean or nearest water body, never to be seen again.  Then, to make sure we can enjoy a cold drink or water our lawns, we take water from hundreds of miles away, pump it through deserts and over mountain ranges, and direct it to our taps and sprinklers without a second thought as to where it came from. 

This paradigm of water management causes a host of problems, from polluting the waterways where our rainfall runoff, or stormwater, ends up being dumped, to contributing to global warming pollution, because pumping water over long distances uses tremendous amounts of electricity (which then further threatens our water supplies by reducing snowfall and surface flows of freshwater we rely on for our drinking water supplies).  Which is where LID comes in:  LID involves cost-effective land use practices that effectively mimic nature's own hydrologic features - instead of channeling rainfall away from where it lands, LID seeks to collect the water onsite to be used later, either by letting it soak into the ground to recharge local groundwater supplies, or by capturing it in rain barrels or cisterns so it can be used to water lawns, flush toilets, or for other non-drinking water applications. 

Because the rainwater, and the pollutants it would otherwise pick up as it flows over paved surfaces never leave the site, the benefit of LID is that it prevents pollution from flowing to our beaches and other waters. But a second benefit is that LID gives us a stable, local supply of water, especially important as we face a continuing drought, and a source of water that is a lot more energy efficient and climate friendly than pumping water from across the state.  It takes a lot less energy to supply water from a tank 10 feet from your house or office, or to pump it from 100 feet down in the ground, than it does to supply it from hundreds of miles away.     

Building on this principle, NRDC recently completed a report, titled "A Clear, Blue Future, How Greening Cities in California Can Address Water Resources and Climate Challenges in the 21st Century." The report concluded that if every new development or redevelopment project at a commercial or residential site in urbanized Southern California and portions of the San Francisco Bay area were built using LID practices over the next 20 years, channeling water into rain barrels, cisterns, or the ground instead of into pipes and gutters, by 2030 we could supply enough water for some 800,000 families in California every year, or roughly two-thirds of the water used by the entire City of Los Angeles.  In fact, every time it rains, up to 10 billion gallons of water pass through Los Angeles' storm drain system alone, enough water in one day to supply more than 60,000 families for a whole year.  By supplying water locally, through nearby groundwater pumping or onsite capture and use, LID practices could also save more than 1.2 million Megawatt-hours of electricity, enough to power more than 100,000 homes each year.  That's the equivalent of preventing more than 535,000 metric tons of CO2 from entering the atmosphere, the same amount emitted by nearly 100,000 cars on the road. 

So the bad news is that drought and climate change will continue to pose a significant challenge to our ability to ensure the safe, reliable supply of water in California.  But the good news is there's a clear, sustainable source of water right outside our doors and windows, falling on our roofs and driveways.  All we have to do is reach out and catch it.