The Irvine Ranch Water District (IRWD) has grown from serving 300 customers in 1961 to over half a million people today, providing water and sewer services to a 181-square-mile service area in Orange County, California. In addition to ambitious water recycling and environmental protection programs, IRWD has also constructed 502 acres of groundwater recharge ponds that it uses to bank low-cost water underground for use in times of dearth. In this interview, IRWD General Manager Paul Cook speaks with Irrigation Leader about the district’s top priorities and also updates us on how the district is continuing its services amid the COVID19 pandemic. 

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Irrigation Leader: Please tell us about your background and how you came to be in your current position. 

Paul Cook: I started my career in the construction industry more than 30 years ago, after graduating from the University of the Pacific in Stockton, California, with an undergraduate degree in civil engineering. My construction experience took me from high-rise buildings to below-ground reservoirs, and while working with the latter, I became interested in all aspects of water treatment and conveyance systems. After 5 years of working in the private sector, I became an engineer at a local water agency near my home in Orange County. While experiencing all the different aspects of working at a full-service water district, I also completed a master of science in civil engineering at California State University, Long Beach. These experiences solidified my interest in a career based in the water industry coupled with local government service. 

Solar power infrastructure is installed at IRWD’s Baker Water Treatment Plant as part of the district’s energy and greenhouse gas master plan.

I went on to become the manager of engineering for the Central and West Basin Water Districts in Los Angeles County, where I oversaw a 5‑year, $350 million capital-improvement program. I joined IRWD in 2004 as the assistant general manager, which proved to be a great fit. This was an agency with plenty of opportunity to grow and apply innovative and sustainable solutions to serving our rapidly growing population, and it was part of my own community. I was appointed IRWD’s general manager in 2011. 

Irrigation Leader: Please tell us about the IRWD’s history and current services. 

Paul Cook: IRWD was established in 1961 to meet the increasing water needs of the region, which at the time was mostly agricultural and ranch land. Since then, the district has grown dramatically—from 300 customers to a daytime population of more than 600,000—and built infrastructure to provide quality drinking water, sewer, and recycled water services to our customers. Today, IRWD’s service area covers 181 square miles, stretching from the ocean to the foothills in central Orange County. It includes all of Irvine, plus portions of Tustin, Lake Forest, Newport Beach, Orange, Costa Mesa, and unincorporated communities. 

Irrigation Leader: Please give us a sense of IRWD’s water storage and delivery infrastructure. 

Paul Cook: IRWD’s drinking water infrastructure includes 1,900 miles of pipeline, 26 wells, 5 water treatment plants, and 36 storage reservoirs. We also have over 1,100 miles of sewer pipeline, 560 miles of recycled water pipeline, 19 recycled water reservoirs, and 2 recycled water treatment plants. Combined, all our pipeline systems could span from the point where IRWD abuts the Pacific Ocean in Newport Beach to the tip of Maine with a few hundred miles left over. It certainly keeps us busy. 

We care about the environment, too, and we have developed and operate 27 urban runoff treatment sites, including the San Joaquin Marsh, one of just two designated Wetlands of Distinction in California. We strive for resilience and sustainability in many ways. IRWD has developed a unique water banking program that safeguards customers from water supply shortages during critically dry years. Our energy and greenhouse gas master plan includes solar power, energy storage, and our brand-new biosolids and energy recovery facility. With these and other renewable resources, we are making a dent in the water-to-energy nexus that challenges our industry. 

Irrigation Leader: What are IRWD’s water sources? 

Paul Cook: Seventy-four percent of IRWD’s water comes from local wells, imported water, and local surface water sources. Recycled water—used for nondrinking purposes— makes up the other 26 percent of our water supply. IRWD began recycling water in 1967, dramatically offsetting our need for imported water, which makes up just 18 percent of our supply today, compared to 66 percent in 1990. 

Irrigation Leader: Please give us a sense of the groundwater situation in IRWD’s service area and how it affects the district. 

Paul Cook: IRWD has a network of 26 high-capacity wells and 3 groundwater treatment plants, which provides enough locally produced groundwater to meet half our total water demands. This has contributed significantly to the district’s resilience and has allowed us to keep our rates the lowest in Orange County.

Irrigation Leader: Please tell us about IRWD’s current and planned groundwater banking and recharge programs. 

Paul Cook: IRWD’s groundwater banking program is designed to provide emergency water supplies to our customers when access to imported water is reduced. To do this, IRWD developed 502 acres of groundwater recharge ponds in Kern County and entered into long-term agreements to capture low-cost water for underground storage during wet periods and recovery for use during dry periods or emergencies. We expect to bank enough water from these projects to meet about 15 percent of our customers’ needs during critically dry years. 

Irrigation Leader: What effects do you expect to see from IRWD’s groundwater storage and recharge programs? 

Paul Cook: Climate change and the state’s aging water system present unprecedented challenges to water districts throughout California. IRWD is addressing these evolving conditions with resilience measures such as diversifying our water sources, expanding recycled water use, and enhancing local water sources that include the water banking program. Water management today relies on a mix of smart and sustainable approaches to adapt to change.

IRWD’s water banking project in Kern County.

Irrigation Leader: What are the district’s other top issues today? 

Paul Cook: Like most organizations, we have had to adapt in response to COVID‑19. I’m proud that we’ve been able to stay healthy and provide uninterrupted service to our community by practicing social distancing, adjusting work schedules, providing proper personal protective equipment to our staff, and making it easy for customers to communicate with us via the Internet, e-mail, and phone. To accommodate customers whose financial situations have changed, we are working with them on payment options while discontinuing our normal practices for shutoffs. 

IRWD has a history of pioneering recycled water uses in the community. Nearly 85 percent of the landscaping in our community’s tree-lined medians, parks, schools, and golf courses is irrigated using recycled water. We also have a proactive program to promote recycled water in dual-plumbed buildings, which has now been implemented in more than 110 structures. IRWD recycled water is used in cooling towers, like those at the University of California, Irvine. We are proud to have partnered with Hyatt House Irvine to establish the first hotel in the United States to use recycled water to flush toilets in guest rooms. Recycled water is also used to make the ice at the Great Park Ice Arena in Irvine. Looking into the future, we are planning new recycled water delivery systems and facilities and an expanded storage reservoir to meet this growing need. We produce recycled water every day, but the community’s demand for it spikes in the summer. Additional storage will help us meet our current and future recycled water needs, even during periods of peak demand. 

Irrigation Leader: What is your vision for the future of IRWD? 

Paul Cook: My vision is to continue our 60-year legacy of sustainability and resilience by identifying and implementing new initiatives and policies in collaboration with the IRWD board, our staff, and stakeholders. We are already mapping out plans to further stretch our use of recycled water, expand our water banking capabilities, and integrate additional energy solutions into our everyday operations. 

IRWD understands that a diverse and sustainable water supply is vital to the health and livelihood of a community, and we are committed to that as we seek out and implement innovations and new technologies for even greater resilience for the future. 

Paul Cook is the general manager of the Irvine Ranch Water District. For more about IRWD, visit