Lessons water managers have learned developing local supplies for Los Angeles could help influence the future of urban water management throughout the West, writes research engineer Erik Porse.

Los Angeles is a grand American urban experiment. It brings emerging ideas into the mainstream, sometimes for better, and sometimes for worse. In the early 20th century, it seemed fanciful to build a metropolis in a region receiving limited seasonal rainfall. But L.A. adopted the ideas of the time at grand scales. It built pipelines over hundreds of miles of rugged terrain to import water from the Owens Valley (1913), Colorado River (1939) and Northern California (1972). In a quest for growth, L.A. has always adopted new ideas to keep ahead.

The myth of L.A. as a desert city persists, but belies local conditions. Los Angeles has always used local water supplies, often preferentially. The region has significant groundwater resources, and in the surrounding mountains, up to 40 inches of rain can fall annually, waiting to be captured. As early as the 1930s, L.A. communities began managing groundwater, limiting pumping and building large spreading basins to recharge runoff from storms. Today, L.A. captures and recharges 200,000 acre-feet annually on average, much more in wet years. Regional agencies also have built “purple pipe” infrastructure for water recycling, which helps recharge groundwater and irrigate landscapes. An additional 40,000–60,000 acre-feet of recycled water is recharged in local basins each year.

If L.A. is an urban laboratory for contemporary ideas, what can it tell us about the future of urban water management in California? Contrary to lore of a thirsty desert city, L.A. demonstrates some well-tested lessons for California’s continually growing cities.

Stormwater Is Already a Resource in California

L.A. County has operated a network of spreading basins for decades with the explicit purpose of groundwater recharge. In past decades, cheap imported water supplemented local stormwater runoff and infiltration.

In recent years, regional agencies have improved systems to capture more runoff and recharge recycled water. The largest annual volume of managed recharge in L.A. County was 630,000 acre-feet (2005–2006). Managed stormwater capture in L.A. was largely developed and funded as part of developing groundwater adjudications.

Throughout Southern California, too, the 2010 Metropolitan Water District Integrated Water Resources Plan reported an additional 400,000 acre-feet of active recharge in other southern counties. The challenge for future stormwater management is to combine centralized and distributed infrastructure to promote recharge and meet water quality regulations without increasing groundwater pollution.

Technology Is Important, but Government Processes Are Critical

New water reuse technologies offer cheaper and more efficient options for water supply and wastewater management. These will be important. But in the end, agency interactions are critical to regional success.

Metropolitan areas often have complex and “polycentric” governance, with duties dispersed across many agencies. In mid-20th-century L.A., the myriad of public and private parties involved in L.A. groundwater basins had to work out collaborative governance structures. They created new entities that served as models for locally driven governance.

Today, the agencies in L.A. responsible for capturing stormwater to recharge groundwater basins are not the agencies that pump the groundwater for water supply. Costs and benefits of projects are mismatched. Multi-benefit projects are often impeded by the difficulties of assembling collaborations with complicated accounting. Some regional progress is underway. For instance, the city of Los Angeles, through its OneWater initiative, is moving toward better integration across water agencies.

The ‘Sticker Price’ of Water Is Misleading

Future projects must examine the long-term costs of alternative water sources when evaluating investments. In urban areas of California, the increasing costs of imported water will likely promote more use of local sources, including stormwater and water reuse.

Today, imported water looks and is cost-effective. But its costs in Southern California have steadily increased, making local alternatives equally attractive over the long term. With or without statewide infrastructure improvements, the increased costs of imported water to Southern California cities, along with desires for regional self-reliance, are driving local agencies to invest in local sources.

No Single Agency Has the Answer

Regional strategies for local water supply enhancement in L.A. necessarily involve many agencies. The regional water importer, Metropolitan Water District, is examining investments in large-scale recycled water from water treatment plants.

Local agencies such as the L.A. Department of Water and Power and the Water Replenishment District of Southern California are investing in ways to promote additional stormwater capture and better estimate natural recharge.

The L.A. County Department of Public Works led a detailed analysis of opportunities to re-operate regional flood control infrastructure and retrofit urban landscapes, with the goal of maximizing stormwater capture and infiltration. Ultimately, the agencies will have to configure collaborative projects that align funding streams with desired regional outcomes.

As a city at the edge, or a canary in the coal mine, Los Angeles provides rich case studies for understanding the future of urban water management in the West.

This story first appeared on California Water Blog, published by the University of California, Davis Center for Watershed Sciences.

The views expressed in this article belong to the author and do not necessarily reflect the editorial policy of Water Deeply.