One City, One Plan, One Water: How Los Angeles Is Transforming Water Management

Carollo Engineers unveils an ambitious plan to turn one of America’s most water-stressed cities into a model of sustainability and resiliency.

By Paul Flick and Inge Wiersema

Los Angeles rambles across nearly 500 square miles of coastal basin in Southern California, brandishing vast beaches, wooded hills, and some of the largest companies and industries in the nation. With a population topping 4 million, a reliable water supply is one of the keys to keeping the city growing and vibrant.

Yet California is now in its fifth year of a persistent and unforgiving drought, straining the city’s ability to effectively manage its various water supplies and sources to meet customer demands. On Oct. 14, 2014, Los Angeles Mayor Eric Garcetti issued Executive Directive Number 5 in response to the lack of rainfall and ongoing drought. From this directive was born the city’s “One Water LA 2040 Plan,” which is an integrated approach for combining water supply augmentation, wastewater treatment, and stormwater runoff capture and management into a $10- to $20-billion capital improvement program. The capital improvements will be part of the city’s ongoing efforts to expand local water supplies by more than 200,000 acre feet per year through recycled water, groundwater recharge, and stormwater (both dry and wet weather) capture and use.

Ultimately, the city hopes to be able to use the river not only as an ecological asset, but as a way to store water for either groundwater replenishment or an alternative to potable water for irrigation.

Once complete, this collaborative plan will both chart the course for managing the city’s future water needs for the next 25 years and answer Mayor Garcetti’s call to make the city’s water supply more resistant to the effects of drought and climate change.

A Model Plan

Carollo Engineers is partnering with the city of Los Angeles in developing and implementing the One Water LA Plan — an effort that is forging new collaborative relationships across the city and driving the development of new tools and technologies to meet the city’s project goals.

The actual One Water LA Plan began with a comprehensive, integrated water model that linked multiple water types and sources to create a water balance tool. This involved an innovative adaptation of Carollo’s Blue Plan-it™ model, which was configured to account for all of the city’s key water supply sources, including a dozen sewer sheds, four wastewater treatment plants, and hundreds of miles of storm drains and channels.

Once the Blue Plan-it modeling framework was in place, Carollo was able to help the city develop and evaluate multiple water supply scenarios against a series of specific criteria, including resiliency to climate change, distributed versus centralized infrastructure, and cost. In addition, the city was able to explore a number of sensitive scenarios to determine the overall robustness of potential solutions to various kinds of uncertainty. The results of these efforts will become detailed facility plans for the production and maximization of recycled water to augment local water supplies, the capture and infiltration of more than 100,000 acre feet per year of runoff to augment groundwater supplies, and the capture and targeted reuse of 85 percent of the stormwater traditionally lost to the ocean. Each of these plans will include triggers that establish clear guidelines for when the city proceeds with subsequent phases of facility construction.

“We reached some interesting conclusions during our modeling efforts,” notes Gil Crozes, Carollo’s One Water LA project director. “We determined that while some of the water management solutions could come from adapting current treatment and monitoring technologies, some of the things the city wants to do in the future will require new and innovative technologies developed by the water industry itself.”

One example of the need for new technologies is found in the city’s oldest waterway, the Los Angeles River. From the earliest days of Los Angeles, the LA River was a key water source for the pueblo and early city residents. However, a series of severe floods in the early 20th century resulted in several flood control measures that transformed the once untamed river into a series of concrete channels.

With growing interest in the LA River as both a water source and recreational area, Carollo is leading the Los Angeles River Flow Study as part of the One Water LA Plan. The study’s objective is to develop a consistent understanding of existing and future flows into the LA River and the water needs to meet the restoration objectives being completed by the U.S. Army Corps of Engineers. This will require new methods to monitor and evaluate the river’s hydrological conditions and sensitive habitats, as well as new ways to maintain existing ecosystems. Ultimately, the city hopes to be able to use the river not only as an ecological asset, but as a way to store water for either groundwater replenishment or an alternative to potable water for irrigation.

Communication As A Key To Success

Naturally, with any large-scale effort involving multiple departments, regulatory agencies, and a host of stakeholders across the city, communication and outreach is critical to project success. To effectively manage stakeholder participation, the city used a three-level framework (Inform — Involve — Collaborate) to better articulate where stakeholder input was going to be most sought. In addition, the city used four different groups to provide input: one-on-one meetings, an advisory group, special topic groups, and the general stakeholder group. Using this layered approach, the city has been able to more quickly and more effectively get the input needed. With Carollo’s support, the One Water LA program has held stakeholder outreach meetings and town hall events for more than 80 neighborhood councils, 15 council districts, and more than a dozen local, state, and federal agencies.

The results from the city of Los Angeles’ One Water LA will be some of the most collaborative and forward-thinking water management planning in the country. One Water LA is demonstrating the ability of a major metropolitan city to come together, cooperate both internally and externally, and make the significant capital planning decisions needed to secure a reliable and sustainable water supply for both new residents and future generations. For Los Angeles, the overall result will be greater public and business confidence which, in turn, will help with raising the funding necessary to implement the One Water LA program. While the lessons learned in Los Angeles will translate to similar cities across the country, until that happens, the One Water LA Plan will set the standard for integrated approaches to water management across a vast range of residential, commercial, and environmental demands.

About The Authors



Paul Flick is Carollo’s corporate communications manager and has 22 years of experience in the civil and environmental engineering industry. He has been with Carollo since 2005.



Inge Wiersema, PE, is Carollo’s project manager for the One Water LA 2040 Plan. She has more than 20 years of experience in water system planning and water resource development.