4R / One Water
When you turn on the tap or flush the toilet, you probably don’t think much about where that water comes from—or where it goes. But in Los Angeles, managing water is anything but simple.
Unlike many places, LA County’s water systems are uniquely fragmented. Our region is home to a complex web of over 200 public and private water agencies serving 4,083 square miles and divided among 89 jurisdictions (cities plus unincorporated areas).
To make things more complicated, these agencies have historically treated different “types” of water—drinking water, stormwater, and wastewater—as separate resources, each with their own sets of policies, often with little to no thought about how these systems could work together to be more sustainable. Or how water systems planning could work synergistically with other types of development (i.e., homes, roads, etc.) to reduce the negative environmental impacts of urban development overall.
While this set-up worked well enough to ensure water security for the region for more than a century, climate change is pushing it to the breaking point. Longer droughts and heavier storms are becoming more common, and our traditional sources of water like mountain snowpack and the Colorado River are drying up, making it more important than ever to make the most of every drop of water we have.
This is where the One Water approach comes in—a way to rethink water management by treating it as a shared, interconnected resource. By breaking down silos and managing water holistically, this approach offers a smarter, more sustainable path forward in the face of a changing climate.
The Problem with LA’s Current Water System
When the city of Los Angeles was founded in 1781, its water needs were modest, and our local water sources were able to meet them. Water flowed through a simple system of crude dams, water wheels, and open-air ditches.
But as the city rapidly expanded into one of the largest in the United States, local sources could no longer keep up with demand. At the same time, LA was facing flooding issues, having built up industries and homes far too close to our rivers and creeks. Rather than addressing these problems holistically, however, the city decided to pursue two separate solutions: importing water from other regions like the Owens Valley, and later the Colorado River and Northern California Bay-Delta, while simultaneously turning the LA River into a giant storm drain, sending its rainwater as quickly as possible straight into the Pacific Ocean.
While this infrastructure was critical in shaping LA into the city it is today, it also came at a tremendous cost: environmental degradation, the displacement of communities, and the beginning of LA’s long dependency on imported water. Today, LA County’s 10+ million residents rely on more than 60% of their water coming from far flung places that can no longer reliably deliver that water, while the vast majority of that imported water ends up getting discharged into the ocean through our wastewater or storm drain systems. By focusing on single-problem, single-solution fixes, we built a fragmented water system that is inherently unsustainable.
What is One Water?
The "One Water" approach, also known as Integrated Water Management (IWM), is a forward-thinking sustainability strategy that views all water—whether it’s groundwater, stormwater, wastewater, or drinking water—as a single, interconnected resource.
While One Water programs can look very different depending on the specific needs of a community, there are a few best practices that most successful programs support:
Capturing Rainwater and Stormwater: Instead of letting stormwater run-off into streets or the ocean, it’s collected and stored for beneficial uses.
Treating Wastewater as a Resource: Wastewater isn’t just disposed of—it’s purified and repurposed for uses like irrigation or even drinking water.
Prioritizing Nature-Based Solutions: Green infrastructure, like wetlands or rain gardens, are used to naturally filter water, recharge groundwater supplies, and support ecosystems.
Integrating Water Resilience into Urban Planning: Water-smart design is embedded into everything we build—homes, businesses, schools, parks, roads, and transit systems. Strategies like Low Impact Development (LID), green streets and alleys, bioswales, and native green spaces help capture, treat, and infiltrate water, reducing runoff and improving water quality.
Cross-Sector Collaboration: Municipalities, water agencies, businesses, and communities work together to align goals and share resources.
What Does One Water Look Like In Los Angeles?
The 4-R Approach
At LA Waterkeeper, we’ve long advocated for what we call the “4-R” approach to urban water management. By Reducing water waste, Reusing urban and stormwater runoff, Recycling purified wastewater, and Restoring contaminated groundwater, we can modernize our water infrastructure and build a local, climate-resilient, and affordable water portfolio.
Thankfully, many of our public agencies have been working on 4R/OneWater solutions for years, launching several major programs to tackle LA’s water challenges, including:
The Los Angeles Department of Water and Power (LADWP) and LA Sanitation (LASAN)’s Pure Water Los Angeles program, which is slated to upgrade the Hyperion Water Reclamation Plant for wastewater recycling, with plans to incorporate up to 210 million gallons a day of this recycled water into the city’s drinking water system.
The Metropolitan Water District’s Climate Adaptation Master Plan for Water (CAMP4W), which is helping guide investments in climate-resilient water supplies, including their Pure Water Southern California recycling project in partnership with the LA County Sanitation Districts, slated to produce up to 150 million gallons of water a day.
LA County’s Safe Clean Water Program, which is funding stormwater capture projects to improve water quality, increase local supplies, and provide community benefits like parks.
Where We’re Falling Short
While such efforts are certainly a step forward, there are still many proposed or ongoing water projects that remain stuck in the old “single problem, single solution” thinking.
Take ocean desalination, for example. While such initiatives sound promising—after all, we have such a large ocean right at our doorsteps—they’re also incredibly energy-intensive and environmentally harmful. In 2019, LA Waterkeeper filed a lawsuit to stop the West Basin Municipal Water District’s plans for a $500 million desalination plant in El Segundo, which would have produced 27–44 thousand tons of carbon emissions annually and discharged millions of gallons of brine and other toxins into sensitive marine habitats. (Thanks to the efforts of LA Waterkeeper, our partners in the SmarterWaterLA coalition, and a key voice on the West Basin board, the agency voted to terminate the project in 2021.)
Another example is the Delta Conveyance Project and related Sites Reservoir Project—a plan to build a massive tunnel to transport water from the Bay-Delta in Northern California to Southern California. Not only would the projects cost more than $20 billion, but they would also further degrade fragile salmon and smelt ecosystems in the Delta and San Francisco Bay and impact local communities, including sensitive Indigenous sites. Finally, for all these costs, the projects fail to account for the reality of a changing climate—will the water they depend on even be there when the project is completed in 2055?
Where We Go from Here
LA Waterkeeper has been a strong advocate for holistic urban water management, promoting policies and projects that enhance water sustainability, resilience, and efficiency.
We played a key role in developing, campaigning for, and now implementing the Safe Clean Water Program (SCWP), established by Measure W in 2018. This program provides $280 million annually to enhance local water supplies, improve water quality, and protect public health through expanded stormwater capture.
As the leading NGO advocate at MWD, we are driving progress on CAMP4W, while also securing funding and approvals for groundwater cleanup projects, such as those in the San Fernando Valley and West Basin. Through the Infrastructure Justice for LA coalition, we also lead advocacy for integrating water and greenspace into housing and transportation projects to create a more sustainable urban landscape.
Finally, we continue to push for strong state wastewater recycling standards, to advance wastewater purification projects, to work to secure hundreds of millions in state and federal funding for wastewater recycling infrastructure.
To adapt to a changing climate, we must prioritize smart investments in solutions that deliver multiple benefits, rather than wasting limited time and resources on narrowly focused projects with more limited or uncertain benefits.
The One Water approach provides a framework for this kind of forward-thinking problem-solving. By prioritizing projects with the greatest overall impact—financially, environmentally, and socially—we can create a resilient, sustainable, and equitable water system that maximizes every drop while protecting livelihoods and ecosystems now and for generations to come.