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1. What is Advanced Treated Water (ATW)?

Advanced Treated Water is recycled water that has received additional levels of treatment to polish the water to the Lake Mission Viejo Association’s water quality specifications.

2. Is Advanced Treated Water safe?

Yes, Advanced Treated Water is safe for recreational activities, including swimming, at Lake Mission Viejo. 

Prior to the extra treatment, Santa Margarita Water District’s recycled water meets state and federal health regulations for swimming lakes (Title 22 of the California Code of Regulations).

3. Is Advanced Treated Water safe for human consumption?

While no ill effects would be anticipated from consuming APW, it is not yet approved for human consumption.

SMWD currently produces recycled water that is treated to standards for irrigation and other unrestricted non-potable uses in accordance with Title 22 of the California Code of Regulations (“Title 22”); including for use in recreational lakes. 

Title 22

LVMA currently purchases Title 22 recycled water from SMWD for irrigation and while Title 22 water can legally be used in the Lake, LVMA has determined that a higher water quality is desirable to maintain the lake quality to support the various recreational uses of the Lake by LVMA members. The District, in consultation with LVMA, has determined that with additional treatment infrastructure, it can produce higher quality recycled water to such standards and in adequate quantities as are necessary to meet the needs of LVMA at the Lake.

4. How much will the project cost?

The projected is expected to cost $5 million. The project is estimated to pay a premium for the water for 20-25 years.

5. Who will pay for the project?

The Lake Mission Viejo Association will pay the capital costs of the ATW treatment facility and for the water that is ultimately delivered for use in the lake.

6. Who approved the project?

Delegates representing the 81 neighborhoods within the 24,217-home Lake Mission Viejo Association voted unanimously to switch to Advanced Treated Water for lake refill and end nearly 40 years of using potable (drinking) water to maintain water levels in the 124-acre Orange County lake. In all, delegates cast 19,803 votes – representing 82 percent of the Association’s homeowners – all in favor of the Association working with the Santa Margarita Water District to construct a new treatment plant to produce Advanced Treated Water for the lake.

7. When will the project be completed?

The project is completed. Lake Mission Viejo is being filled with Advanced Treated Water, as needed.