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Syphon Reservoir Improvement Project

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An Investment in Our Community's Future

The Syphon Reservoir Improvement Project is an investment to increase the capacity of the existing Syphon Reservoir, which is part of Irvine Ranch Water District’s recycled water system. The project will allow IRWD to store more recycled water to meet seasonal and future needs. By making more recycled water available, IRWD will reduce its dependence on costly imported water, making the community’s water supply more self-sufficient and protecting against future droughts.

The proposed project has undergone a thorough California Environmental Quality Act review process that included opportunities for public input and stakeholder engagement. A Final Environmental Impact Report (EIR) for the project was approved by the IRWD Board of Directors on July 26, 2021.

  Download Project Information

Value of Recycled Water 

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Project FAQ

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Project Fact Sheet

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Korean - 한국어


  Project Overview

Syphon Reservoir Improvement Project: Investing in Our Future
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The Syphon Reservoir Improvement Project is an investment to increase the current Syphon Reservoir storage capacity from 578 acre-feet to 5,000 acre-feet (from 188.3 million gallons to 1.6 billion gallons). By doing so, we can store more recycled water to meet seasonal and future needs. By making more recycled water available, we will reduce our dependence on costly imported water and make our community more self-sufficient.

Project Benefits

The Syphon Reservoir Improvement Project will help IRWD meet the community’s need for increased recycled water storage. By increasing our ability to store more recycled water, the project:

  • • Prepares us for the future by storing more drought-proof water.
  • • Enables IRWD to use nearly 100% of the recycled water it produces.
  • • Keeps our community green and beautiful.
  • • Provides water to fight wildfires throughout the region.
  • • Saves IRWD $100 million over 50 years and preserves low customer rates.


Final design for the project is expected to be completed in January 2025. Construction is anticipated to begin in spring 2025 and is expected to take about five years to complete.


  How the Recycled Water System Works


Meeting Community Water Needs

Recycled water is an abundant, affordable and reliable part of Irvine Ranch Water District’s diverse water supply portfolio. We have one of the most robust and technologically advanced recycled water systems in the nation, which helps us meet the water needs of our community, while responsibly preparing for the future.

To learn more about IRWD’s innovative recycled water system, visit our recycled water webpage.


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 Why Lose It When We Can Use It?

Drinking water is limited, especially here in Southern California. So how does Irvine Ranch Water District keep our communities so green and beautiful without depleting the drinking water we depend on in our homes and businesses?

The answer is recycled water—an abundant, affordable and drought-proof source of water ideal for many uses. Just not for drinking. Every gallon of recycled water we use for these purposes saves a gallon of drinking water. And that adds up to 28 million gallons a day.


How Important Is Recycled Water?

Recycled water is a crucial, reliable source in our diverse water supply portfolio and a forward-thinking solution for the future of our community. It’s all about using the right water for the right purpose.

Recycled water fast facts:

  • • 27% of our water supply is recycled water.
  • • 60% of all recycled water is used for landscape irrigation, 30% goes toward business and industrial uses and 10% is used for agriculture.
  • • 85% of all common areas throughout the IRWD community are irrigated with recycled water.

The Water Balancing Act

Managing our water supply is a balancing act. Recycled water is produced and used every day, but the community’s need for it grows during the dry months of summer. In the wet winter months, when demand is low, our recycled water reservoirs fill up, and excess recycled water goes to waste. Without more room to store recycled water for times of high demand, we will have to use expensive imported water to meet our future needs.

Always Our Top Priority

At Irvine Ranch Water District, safety is always our top priority. For more than 60 years, we have safely owned, operated, and maintained reservoirs and dams for the benefit of our community. We are committed to providing our customers and the community with excellent service, along with peace of mind. Our state-of-the-art Dam Safety Program and our safety-first approach to operations help to ensure that when it comes to safety Irvine Ranch Water District has your back.

The Syphon Reservoir Improvement Project will modernize and upgrade the existing recycled water reservoir so it continues to meet or exceed the latest federal and state safety standards. The proposed project will be peer reviewed through a rigorous process overseen by a technical advisory group made up of respected engineers and safety experts.

To learn more about IRWD’s Dam Safety Program or how our engineers and dam safety experts are working to ensure that the Syphon Reservoir Improvement Project will be built safely and responsibly, please visit our Dam and Reservoir Safety webpage.

Safety Links

• Current and proposed Inundation Maps for Syphon Reservoir.

Final Technical Memorandum on inundation modeling for the Syphon project.

Emergency Action Plans for all IRWD dams.  

  Independent Design & Safety Review Panel


IRWD has established an Independent Design & Safety Review Panel of nationally recognized dam industry experts. The Review Panel will provide an objective, third-party peer review of the design, engineering and safety of IRWD’s Syphon Reservoir Improvement Project. This independent panel of experienced professionals will confirm that state and federal design standards have been met and that the project meets IRWD’s high standards for quality and community safety.

Independent Design & Safety Review Panelists

Lelio Mejia, PhD, PE, NAE – Senior Principal Engineer, GeoSyntec Consultants, Oakland
(Geotechnical, Seismic, Geology, Dam Design)

More than 40 years of experience in geotechnical and earthquake engineering for 25+ large earth dams. Design and construction of more than 15 major dam projects worldwide. Contributor to advancing the state of practice for seismic analysis and earthquake loading criteria for the safe design of dams throughout the US, including consultation for the state Division of Safety of Dams. Chair of the United States Society on Dams (USSD) Earthquakes Committee; Member of the International Commission on Large Dams  Committee on Seismic Aspects of Dam Design; Member of the National Research Council (NRC) Committee for the State of the Art and Practice in Earthquake Induced Soil Liquefaction Assessment. Ph.D., Geotechnical Earthquake Engineering, University of California, Berkeley; M.S., Geotechnical Engineering, University of California, Berkeley; B.S., Civil Engineering, Universidad Javeriana, Bogota, Colombia.

Faiz Makdisi, PhD, PE, D.GE – Senior Consultant, Gannett Fleming, Sacramento
(Geotechnical, Seismic, Geology)
Forty-five years of experience in geotechnical and civil engineering. Directly involved in applied research and analysis of foundation/earthquake engineering and safety evaluations of earth-fill and rock-fill dams.  Member of the U.S. Bureau of Reclamation Board of Consultants for Conconully and El Vado Dams. Performed Federal Energy Regulatory Commission (FERC) safety inspections and facilitated safety inspections for more than 80 dams. Facilitated dam risk and safety workshops for more than 40 dams. Ph.D., Geotechnical and Geoenvironmental Engineering, University of California, Berkeley; M.S., Geotechnical and Geoenvironmental Engineering, University of California, Berkeley; B.E., Civil Engineering, American University of Beirut, Lebanon.

Dan Hertel, PE – Co-Founder, Engineering Solutions, Denver
(Construction/Cost Estimating)
More than 37 years of experience in the construction of dams, pipelines and tunnels. Expertise encompasses risk assessments, constructability analysis and review, and construction sequencing for safe and proper execution of large dams. Member of Association of State Dam Safety Officials and past President of USSD. B.S., Construction Engineering, Montana State University.

John Trojanowski, PE – Trojanowski Dam Engineering, Denver
(Hydraulic Structures, Risk-Informed Decision-Making, USBR- Retired)
More than 42 years of engineering experience related to dams and waterways. 37 years with the Bureau of Reclamation’s Dam Safety Program and Retired Manager of the Waterways and Concrete Dam Group. Facilitated and participated in numerous risk analyses and dam safety advisory groups for the Bureau of Reclamation, U.S. Army Corps of Engineers, California Department of Water Resources, and other agencies. B.S., Civil Engineering, University of Colorado at Boulder.

Brett Sanders, PhD – Professor, Civil and Environmental Engineering, University of California, Irvine
(Civil, Downstream Hydrology/Flooding)
Researcher specializing in information technologies to create more accurate and efficient simulation tools, flooding and erosion hazards and urban flooding. Expert in surface water quality, low-impact development impacts on hydrology, dam-break flooding, aerial and terrestrial lidar scanning and geographical information systems. Interim Associate Dean for Undergraduate Student Affairs. Ph.D. Civil Engineering, University of Michigan; M.S. Civil Engineering, University of Michigan; B.S., Civil Engineering, University of California, Berkeley.

  Environmental Review

Final EIR - Full Document

Draft EIR - Executive Summary 


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Korean - 한국어

Draft EIR - Notice of Availability 


Draft EIR - Full Document



  Local Resources Program Funding


LRP Estimator (.xls download)

  Project Supporters


  • • Asian Business Association Orange County
  • • Asian Industry B2B
  • • Asian Women Entrepreneurs
  • • Black Chamber of Orange County
  • • Chinese American Mutual Assistance Association
  • • Diversity Business Network
  • • Filipino American Chamber of Commerce of Orange County
  • • Greater Irvine Chamber of Commerce
  • • I Love Irvine
  • • Nightingale Technology
  • • Orange County REALTORS Association
  • • Orange County Business Council
  • • Orange County Hispanic Chamber of Commerce
  • • Shadetree Partnership
  • • South Coast Chinese Cultural Association
  • • South Orange County Economic Coalition
  • • Vietnamese American Chamber of Commerce
  • • A.G. Kawamura
  • • Alice Lei
  • • Diana Zuniga
  • • Gloria Rull
  • • Jeannie Luong
  • • Jennifer S. Wang
  • • Jerry Chang
  • • Linda Nguyen
  • • Robert (Bobby) McDonald
  • • Tim Cheng
  • • Tom Nguyen
  • • Wendy Yoo
  • • Zhihai Li
  Get Involved
IRWD is Committed to Transparency and Community Engagement

IRWD has a longstanding and ongoing commitment to transparency. It welcomes neighbors and community members to share their questions and comments about the project. IRWD will keep the community informed about the project, public meetings and comment periods through a variety of communications including advertising, direct mail, open houses, website, e-newsletter, social media and a speakers’ bureau.

Send an email to to sign up for updates on the project

Scoping Meeting Information Packet -- Aug. 21, 2019