The Aliso Watershed Protection & Preservation Project


Overview: The Aliso Watershed Protection & Preservation Project replaces decades-old infrastructure with newer, more reliable pipe to protect the natural environment, beaches, ocean and local water quality. 

Background: Since the early 1980s, two four-inch metal pipes have carried sludge – the solid byproduct of wastewater treatment – from the Coastal Treatment Plant in Aliso Canyon to a facility about three miles north for safe disposal or recycling. These aging pipes are in urgent need of repair as a break would have significant environmental consequences for Aliso & Wood Canyons, Aliso Creek, Aliso Beach and the Pacific Ocean.

Solution: The Aliso Watershed Protection & Preservation Project is a 50-year solution to this challenge. It includes installation of a new, six-inch high density polyethylene (HDPE) pipe to ensure the safe transmission and treatment of sludge. The new pipe will also run along a similar path to the existing pipes to minimize disruption to the natural environment. Additionally, the project will provide habitat restoration for added environmental enhancements to the region.

Project Location: The project is located in Aliso & Wood Canyons Wilderness Park. SOCWA is working closely with the County of Orange and other stakeholders to ensure minimal disruption to park services. Park visitors may notice construction activities and signage. 


What is the Aliso Watershed Protection & Preservation Project?

This project replaces two pipes that have outlived their lifespan with a new, state-of-the-art line. Each day, the current pipes carry up to 89,000 gallons of sludge – the byproduct of wastewater treatment process – about three miles for final treatment. The project replaces these dangerously old pipes to avoid potential breaks and the environmental consequences that would result.

Why is this project necessary?

The original pipe was installed in 1982 and has served its lifespan. 

Who is leading this project?

The South Orange County Wastewater Authority (SOCWA) is leading this project on behalf of the agencies that participate in the Coastal Treatment Plant.

How long will this project take?

Construction is anticipated to last through Fall 2021.

What is being done to protect Aliso Creek? 

First and foremost, the new line will largely follow the path of the old lines to minimize and eliminate impacts. SOCWA will also be responsible for creating over 7 acres of new habitat to enhance the natural environments of South Orange County. These plans have all undergone considerable review from environmental agencies, including the California Coastal Commission and Regional Water Quality Control Board.

How are we protecting the natural resources during construction?

Biological, palaeontological, and cultural monitors will be on-site during construction to monitor natural resources and to prevent unnecessary disturbances.

For more information, please email or call (949) 234-5425.


Final Environmental Impact Report