Natural Treatment System

Natural Treatment System

Natural Process. Clean Water.

The Natural Treatment System is a cost-effective, environmentally sound method for treating dry weather runoff. It is modeled after the successful system of natural treatment ponds which remove nitrogen, phosphorus and bacteria from surface waters entering the IRWD San Joaquin Marsh. Watch our video on this Natural Treatment System, or view and print our Natural Treatment System Fact Sheet. 

In simple terms, the Natural Treatment System works much like the San Joaquin Marsh, only using smaller man-made wetlands placed strategically throughout the watershed. Low-flow natural and urban runoff, as well as smaller storm flows, are diverted into man-made wetlands throughout the San Diego Creek Watershed. In these wetlands, contaminates are removed and prevented from reaching the Upper Newport Bay.

landscape open house

Treating urban runoff is one of IRWD's core responsibilities. Section 35539.12 of the California Water Code grants IRWD the authority to construct, maintain and operate urban runoff treatment facilities within our service area. The Natural Treatment System also provides riparian habitat and water-quality benefits benefits to wildlife throughout the watershed.


 Current Natural Treatment Sites


NTS Frequently Asked Questions

Download NTS Design Guidelines »
What is NTS?+
What is Urban Runoff? +
Why is the NTS necessary? +
NTS Guidelines +
Who are partners involved with NTS? +
Who maintains the NTS? +
Are NTS sites accessible to the public? +

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