“Across the arid west, we’re facing depleted or threatened water supplies for millions of people,” said Noah Garrison, NRDC water program attorney. “We need to be smarter with our water use. Low impact development maximizes water and energy savings while reducing global warming pollution. Water can easily be collected and used on-site instead of being dumped into local waterways, where it’s not only wasted, but contributes to unnecessary water pollution.”
The report, A Clear Blue Future: How Greening California Cities Can Address Water Resources and Climate Challenges in the 21st Century, highlights low impact development, or LID, as a land planning and engineering design approach for stormwater management. LID enables cities, states, and individuals to increase access to safe and reliable sources of water while reducing the amount of energy consumed and global warming pollution generated when delivering water to residents.
The study found that implementing LID practices that emphasize capture and infiltration at new and redeveloped residential and commercial properties in the urbanized areas of Southern California and portions of the San Francisco Bay Area has the potential to increase local water supplies by up to 405,000 acre-feet of water per year by 2030—an amount roughly equivalent to two-thirds of the water used by the entire City of Los Angeles each year.
“Our analysis found that significant opportunities exist to improve local water supply reliability in both southern and northern California by capturing rainwater for beneficial use,” said Dr. Robert Wilkinson, co-author, UCSB. “While LID is only part of the answer to our water supply needs in the state, the energy, climate, water supply, and pollution prevention benefits of LID applications is an opportunity to be tapped.”
Overall, the collection, distribution, treatment, and safe disposal of drinking water and wastewater consume tremendous amounts of energy nationwide and release approximately 116 billion pounds of carbon dioxide (CO2) per year—as much global warming pollution each year as 10 million cars. The report found that 1,225,500 megawatt hours of electricity savings can be achieved each year through use of LID practices in California, representing enough energy to power more than 102,000 single-family homes for one full year.
The LID report found that reducing imported water from location inefficient sources in Northern California or from energy intensive sources such as ocean desalination could prevent as much as 535,500 metric tons of CO2 from entering the atmosphere annually, the equivalent of taking more than 97,000 cars off the road each year.
“Low impact development practices represent the state of the art in stormwater management today for the protection of water quality and aquatic ecosystems,” said Dr. Richard Horner, co-author, University of Washington. “These key benefits can be added to the very important additional advantage of contributing to the supply of water to California citizens and reducing or even removing the threat of future deficits now facing the state. All communities throughout California can contribute to this solution by harnessing the resource given by the skies above, instead of quickly sending it uselessly downstream only to cause environmental and flooding problems.”
More than 100 million acres of land have been developed in the United States, and with development and sprawl increasing with population growth, the risks to water supply and quality are growing. LID is a simple and cost-effective green development strategy that can help cities, states, and even individuals meet the water supply challenge, clean up our existing water resources, and, in many places in the West, curb global warming pollution by reducing the amount of electricity used to supply water.
As global warming threatens our water resources, communities are faced with a need to respond quickly and economically to water supply shortfalls. Both the snowpack and surface runoff that form a critical supply of potable water for western states are being affected by higher temperatures. Infiltration or local capture and use of rainwater provides a cost-effective option to enhance water supplies.
LID uses smarter city design such as permeable pavement to infiltrate rainwater into the earth and recharge groundwater supplies. It also uses cisterns (large water tanks) and rain barrels to capture rainwater for use where it falls. This reduces the runoff that contaminates waterways, while at the same time collecting clean water that can be used to meet our water supply needs.