Ocean Discharge

Our job is to clean wastewater and safely reintroduce it into the environment. After primary and secondary wastewater treatment, water quality meets or exceeds all regulatory standards for discharge into the ocean. If the secondary effluent is not needed as source water for our water projects, it travels via underground pipe from the Regional Treatment Plant and out into the ocean.

Ocean Outfall Pipeline 

Monterey One Water’s ocean outfall pipeline is about four miles long: two miles from the Regional Treatment Plant to the coast and two miles into the ocean. The pipeline has a 60 inch diameter and extends 100 feet below the surface of the ocean. Satellite imagery shown below picks up the presence of the pipe though it is undetectable by sight if flying overhead.

Interesting Fact
The end of the ocean outfall pipeline is actually closed. Water is dispersed into the ocean via ports along the last 1,000 feet of the pipeline. These ports, located at 3 o’clock and 9 o’clock, help the fresh water mix with more dense salt water.

Water Quality

Extensive Federal and State water quality standards are in place to protect pollutants from re-entering the environment and causing harm. Only permitted operations can legally, and therefore safely, discharge treated wastewater. Samples are collected every day from various locations within the treatment processes and effluent water. A wide variety of tests are then performed in Monterey One Water’s certified laboratory to ensure compliance with the water quality parameters outlined in our permit:

  • Order No. R3-2018-0017 (PDF)
    National Pollutant Discharge Elimination System (NPDES) No.: CA0048551
    Issued By: California Regional Water Quality Control Board, Central Coast Region

As an ocean discharger, standards set in our permit must meet standards set by the United States Environmental Protection Agency in addition to the California Ocean Plan issued by the State Water Resources Control Agency and California Environmental Protection Agency.


Members of the public can access water quality data by searching Monterey One Water under Agency Name in the following database:

Satellite map of ocean outfall pipeline