Trampas Canyon Reservoir & Dam

Water for a Resilient Future

It is undeniable. Our community, like so many others in California, faces risks to our water supply from earthquakes, droughts, aging infrastructure, and more. But thanks to the vision of Santa Margarita Water District’s Board and the tireless efforts of its staff and contractors, a new insurance policy is in place to help reduce the impacts of those risks while ensuring a more resilient water supply. That insurance policy is Trampas Canyon Reservoir.

Trampas Canyon Reservoir represents a bold step forward for a sustainable water supply for future generations. It is a smart, eco-enhancing resource that captures and stores highly treated wastewater so that it can be used for irrigation instead of drinking water.


Quick Facts

Largest surface water reservoir in south Orange County. Spanning 3,000 feet high and reaching over 80 feet in depth at its lowest point

Helps us use 100% of our community’s wastewater, building regional sustainability and resiliency.

Creates an additional 1.6 billion gallons of recycled water storage – enough water to fill 2,500 Olympic-size swimming pools.

Saves drinking water supplies by using recycled water to water parks, medians, and common area landscapes.

Features three dams. The main dam reaches 216 feet high. 

History of Trampas Canyon Reservoir

In the early 1970s, a reservoir was built as part of the sand mining operation in the hills south of Ortega Highway in Rancho Mission Viejo. More than 40 years later, Santa Margarita Water District envisioned a new use for the abandoned reservoir: to create winter storage for recycled water that could be used during dry, hot months to water landscapes.

A new era of water sustainability in south Orange County was born, as SMWD worked with Rancho Mission Viejo and acquired the land in 2017. This $123 million investment was paid for through a State Water Resources Control Board low-interest loan, a Proposition 1 grant, Rancho Mission Viejo, designated District reserves, and other funds.

How Trampas Canyon Reservoir Will Work

Trampas Canyon Reservoir will capture and store recycled water from the Chiquita Water Reclamation Plant and other recycled water supply sources. Currently, Chiquita Water Reclamation Plant is capable of producing recycled water year-round, but during the winter months water demand is so low that treated wastewater flows to the ocean. With the storage capacity of Trampas Canyon Reservoir in place, our community can now store this treated wastewater for use in the summer when demands are high. That’s why Trampas Canyon Reservoir is a real game-changer for the region!

Environmental Benefits

SMWD balances construction and operation of the reservoir with the preservation of open space and wildlife habitat. Throughout construction, biologists worked to ensure that the project would enhance the region as a continued habitat for many species of birds, invertebrates, and small and large mammals.

Toward a Water Resilient Future

Saving recycled water in the winter or wet months for use in the dry months is a key benefit of Trampas Canyon Reservoir. In the future, the reservoir may even expand our region’s drinking supply by adding recycled water to groundwater aquifers or even the drinking water system directly.


Orange County Leaders Join SMWD to Celebrate
Trampas Canyon Dam and Reservoir Dedication

The dedication of Santa Margarita Water District's Trampas Canyon Dam and Reservoir on Friday, October 9, 2020 marked an important step in securing water supply resiliency for the south Orange County community. Local elected, regional, and state officials as well as community leaders joined the District Board of Directors and staff to commemorate the completion of this latest (and area’s largest) infrastructure project. Read more...

Take a Virtual Tour of Trampas Canyon Dam & Reservoir