Syphon Reservoir Improvement Project

Syphon Reservoir Improvement Project

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Improvements to the Syphon Reservoir will allow IRWD to maximize the use of recycled water throughout its service area, reducing dependence on imported water supplies.


Irvine Ranch Water District owns and operates one of the largest, most technologically advanced recycled water systems in the nation. Recycled water dramatically reduces demand for drinking water and currently makes up more than one-fourth of the District's entire water supply. It is a high-quality, drought-resilient source of water that keeps parks, medians, golf courses and HOAs green.

The Syphon Reservoir Improvement Project, a $75 - $95 million investment, proposes to expand the existing recycled water storage reservoir and dam, upgrade the reservoir to a modern design that will meet state and federal safety standards, and increase seasonal storage capacity to benefit all IRWD customers.

Project Overview+

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Meeting Local Water Supply Needs

Recycled water is a vital, reliable and economic source of water in the District's diverse water supply portfolio that is used for:

- Landscape Irrigation
- Crop Irrigation
- Business Uses
- Industrial Uses

 Project Benefits

The Syphon Reservoir Improvement Project will help IRWD meet the community’s need for increased recycled water storage. It will:

- Provide an enhanced drought-resilient source of water
- Reduce the District’s dependence on imported water
- Enable IRWD to use nearly 100% of the recycled water it produces
- Keep parks, medians, school athletic fields, public and community landscaping, and golf courses green and beautiful
- Provide recycled water for agricultural uses that produce locally grown foods
- Support commercial and industrial needs such as dual-plumbed buildings and cooling towers
- Free up drinking water for use in homes and businesses, rather than for irrigation
- Save money and preserve low customer rates

A Commitment to Transparency

IRWD has carefully analyzed various project alternatives to consider all water-supply, environmental and financial considerations. The project will be subject to rigorous state and federal environmental review processes, including extensive opportunities for public input and stakeholder engagement.

 Fact Sheet: Syphon Reservoir Improvement Project

Water Supply Benefits+

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A Recycled Water Storage Solution

The Syphon Reservoir Improvement Project is an investment to expand the existing recycled water storage reservoir to increase storage capacity for use throughout the service area, which will benefit all Irvine Ranch Water District customers.

Serving Our Community

The Syphon Reservoir Improvement Project will keep landscaping in the community green and beautiful, supply the local economy’s commercial and industrial needs, and support fertile agricultural areas.

IRWD provides recycled wherever possible for watering parks, medians, school grounds, golf courses, freeway landscaping, and common areas managed by many homeowners associations throughout the district.
Commercially, recycled water is utilized in various dual-plumbed office buildings, concrete production, cooling towers, and construction-related activities.
The majority of agricultural irrigation within the District is also from recycled water, which reduces demand on the drinking water supply.

Leading the Way

IRWD operates one of the largest and most technologically-advanced recycled water systems in the nation:

- Approximately 9.7 billion gallons of recycled water delivered per year
- 545 miles of recycled water pipelines
- 4 recycled water storage reservoirs
- 5,700+ metered recycled water connections

What Customers are Saying

- 77% of customers are aware that IRWD uses recycled water for medians, parks and other green spaces.
- 90% of customers support IRWD using recycled water for medians, parks and other green spaces.

A Seasonal Storage Solution

Since recycled water is most commonly used for irrigation, the need for it fluctuates considerably based on wet- and dry-season weather patterns. The proposed reservoir improvement will allow IRWD to store more recycled water during wet seasons for reuse when the weather is dry.

Investing in the Future

IRWD depends on a diverse portfolio of water sources. By expanding its stored supply of recycled water and making more available for use, the Syphon Reservoir Improvement Project will help IRWD become more self-sufficient and reduce its dependence on costly imported water.


Safety First+

Reservoir Experts

Irvine Ranch Water District is an experienced reservoir operator with an exemplary record of construction, performance and dam safety. The District is committed to keeping its critical infrastructure safe and operational for the benefit of the entire community.

Strong Safety Record

IRWD operates five earthen embankment dams. All of them meet a “satisfactory condition” rating — the highest level of safety assigned by the California Department of Water Resources, Division of Safety of Dams (DSOD). Dams classified under this rating have no existing or potential safety deficiencies identified.

Going Above and Beyond for Safety

Safety is IRWD’s top priority. In addition to the state-mandated inspections mentioned above, the District invests in making sure its existing infrastructure and facilities are well-maintained and safe.

- Retains dam safety experts to inspect its dams annually
- Visually inspects its dams daily
- Measures and analyzes drain flows, monitoring wells, groundwater, and other fluid pressure monthly

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 Case in Point: San Joaquin Reservoir

The San Joaquin Reservoir – built by IRWD in 1966 – has stood the test of time and was retrofitted in the 1990s to store recycled water. The support expressed by the community in response to the project’s completion is a testament to IRWD’s inclusive and transparent stakeholder engagement process.


Strong Track Record+

Trusted Agency. Strong Track Record.

Established in 1961, Irvine Ranch Water District is part of the fabric of Central Orange County, serving more than 403,000 residents and a robust business community. The District provides high-quality drinking water, groundbreaking recycled water programs, environmentally sound urban runoff treatment, and reliable sewage collection and treatment system.

 A Legacy of Successful Projects

For nearly 60 years, IRWD has safely built and operated water infrastructure projects to benefit the community. Safety is always the top priority, and the District has a proven ability to complete complex capital improvement projects while minimizing construction impacts on the surrounding community.

 Building and Operating Best-in-Class Facilities

IRWD’s infrastructure and facilities are well-maintained with an excellent safety and performance record:

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Michelson Water Recycling Plant

This plant, shown above, converts an about 20 million gallons of sewage each day into recycled water that is used for landscape irrigation, industry, and toilet-flushing in dual-plumbed buildings. Built in 1961 and significantly expanded in 2014, it is IRWD's primary source of recycled water.


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San Joaquin Reservoir and Dam

This reservoir in Newport Coast was built by IRWD in 1966 to store drinking water. After a law was passed prohibiting drinking water storage in open reservoirs, IRWD converted it in 2005 to store a billion gallons of recycled water for nondrinking uses such as irrigation, cooling towers and other commercial and industrial processes.


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Irvine Desalter Project

High-salinity groundwater is pumped from five wells located near the I-5 Freeway in Irvine and sent to this treatment facility, which removes the elevated levels of salt — establishing a previously untapped source of local groundwater. The result is 1.7 billion gallons per year of purified drinking water, enough for 50,000 people.


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Natural Treatment System

The District's Natural Treatment System features a series of 35 man-made wetlands placed strategically throughout the IRWD service area. It is a cost-effective, environmentally sound method for treating dry-weather runoff before it reaches the Upper Newport Bay. NTS is modeled after the successful system of natural treatment ponds that remove nitrogen, phosphorus, and bacteria from water entering IRWD’s San Joaquin Marsh.


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Baker Water Treatment Plant

A joint project of IRWD and four South Orange County water districts, this facility in Lake Forest provides 28.1 million gallons of drinking water per day to the five districts. The plant, which opened in 2017 and is operated by IRWD, ensures a reliable water supply by increasing local water treatment capability from multiple sources.


Wells 21 & 22 Water Treatment Plant

This facility recovers and treats impaired local groundwater for use as drinking water, helping to satisfy increased demand. It produces about 800 million gallons per year for the IRWD service area.


Get Involved+

Seeking Meaningful Community Engagement

IRWD welcomes members of the community to share their questions and comments and provide feedback about the project.

To begin that dialogue, please provide your comments at


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