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April 24, 2024 3:22PM
April 24, 2024 15:22PM

customer care

Dam and Reservoir Safety

Full video with subtitles:  English       中文字幕       한국어 자막 


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 operate five reservoirs in and around our service area: Rattlesnake, San Joaquin, Sand Canyon, Syphon, and Irvine Lake.

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.

Video Part 1: History of ownership
Subtitled:  English       中文字幕       한국어 자막 

  Dam Safety Program


Safety drives everything we do at Irvine Ranch Water District. We continually monitor, inspect and maintain our dams and reservoirs. But that’s not all. Our engineers and dam safety experts are implementing a state-of-the-art Dam Safety Program that will exceed all current state standards, and even provide a roadmap for other agencies to follow. This new program combines the traditional tried and true safety standards with a modern Risk-Informed Decision-Making process, known as RIDM.

RIDM is a rigorous, systematic and thorough approach to dam safety that identifies and reduces any risks. Incorporating RIDM will create one of the most robust dam safety and reservoir management programs in the nation. Irvine Ranch Water District’s Dam Safety Program builds on industry best practices to ensure that our dams and reservoirs will always be safe.

Video Part 2: Dam safety program
Subtitled:  English       中文字幕       한국어 자막 

  Safe Operation and Management


Managing our community’s water supply is a balancing act. In the warm and dry months of summer, our community’s demand for water increases. During cooler, wet winter months, demand dips and we’re able to fill up our reservoirs and save water for the summer. IRWD reservoirs near residential communities receive very little or no water from rivers or streams. That means we can completely control the flow of water in and out — like filling or draining your bathtub.

For our reservoirs that do receive water from rivers or streams, we can manage the water level during heavy rainfall by safely releasing water into our recycled water system, downstream creeks, or open spaces.

Reservoirs and dams increase our community’s self-reliance by safely storing local water. This protects our community against future droughts and helps to preserve low customer rates.  Water from these reservoirs is also used by fire crews to put out wildfires.

Video Part 3: How our reservoirs work
Subtitled:  English       中文字幕       한국어 자막 

  Design, Regulation and Oversight


IRWD’s dams and reservoirs are designed for safety. All five of our reservoirs use engineered earthen embankment dams — the most common type of dam found throughout California. Compacted earth and rock materials are used for these structures because they’re proven to be resilient and self-healing in earthquakes. These types of dams consistently have strong safety records, and they blend with the natural environment.

Video Part 4: Safety systems in place
Subtitled:  English       中文字幕       한국어 자막

Regulation and Oversight

 In California, dams are regulated by the California Department of Water Resources Division of Safety of Dams (DSOD). DSOD inspects the Irvine Ranch Water District dams at Sand Canyon, Rattlesnake, and Syphon reservoirs once every year. The dams at Santiago Creek Reservoir (Irvine Lake) and San Joaquin Reservoir are inspected twice a year. DSOD provides a safety rating for each of IRWD’s dams based on several factors including the height of the dam and the storage capacity of the reservoir. DSOD has concluded that all IRWD dams are safe for continued use.

2022 Annual DSOD Inspection Reports (pdfs)

Approximately 1,250 dams in California fall under state jurisdiction. DSOD has several programs that ensure dam safety. DSOD inspects each dam at least once per year to ensure the dam is safe, performing as intended, and not developing problems. DSOD also reviews the stability of dams and their major facilities in light of improved design approaches and requirements, as well as new findings regarding earthquake hazards and hydrologic estimates in California. Dam safety in California is governed by laws, regulations and current practices that are available on the DSOD website.

2021 Annual Surveillance Reports (pdfs)

Going Above and Beyond for Safety

 To ensure we’re going above and beyond for safety, IRWD retains a team of engineers and dam safety experts who have been nationally recognized as some of the best in the field, including geotechnical consultants who specialize in dams. In addition to the state-mandated inspections mentioned above, IRWD’s dam safety team conducts an extra semiannual inspection of San Joaquin, Rattlesnake, Sand Canyon and Syphon reservoirs and quarterly inspections of Santiago Creek Reservoir (Irvine Lake). IRWD staff visually inspects all five dams daily. Also, caretakers live onsite at the San Joaquin, Rattlesnake, Sand Canyon, and Santiago Creek Reservoirs and observe the dams daily.

Measurements of drain flows, monitoring wells, and piezometers are taken monthly. Piezometers are used to measure groundwater and other fluid pressure levels. Dam crest survey markers, which give us the ability to measure horizontal or vertical movement of the dam, are measured by a licensed surveyor annually. The results are evaluated to determine if there are any adverse trends that need to be addressed.

Our commitment to the community includes developing and maintaining an Emergency Action Plan for each of our dams to identify potential emergency conditions, and preplanned actions to ensure safety. In the highly unlikely event of an emergency, residents in the area would be notified and directed to helpful resources. You can learn more here about how IRWD works with regulators at the state level and coordinates with local public safety personnel to develop and maintain the Emergency Action Plans.


  Commitment to Community Conversation


IRWD is committed to safety, and we’re committed to maintaining a transparent conversation with our community. To learn more about IRWD’s state-of-the-art dam safety program or how our engineers and dam safety experts are working to ensure all of our dams and reservoirs continue to meet or exceed the latest state and federal safety standards, please contact us at


  IRWD Reservoirs with Dams


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Rattlesnake1 5x4.jpg

Sand Canyon Reservoir

 Rattlesnake Reservoir

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 Syphon Reservoir

 Santiago Creek Reservoir (Irvine Lake)

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San Joaquin Reservoir