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F.E. Weymouth Treatment Plant

The F.E. Weymouth Treatment Plant at La Verne in the San Gabriel Valley is one of five such treatment plants within the Metropolitan Water District system.

Weymouth was the first filtration plant built by Metropolitan, and today, largely serves Los Angeles and Orange counties.  Completed in 1940, it is noted for its Mission Revival style architecture and features a blue-tiled bell tower, graceful arches, a vivid district seal mosaic and colorful tiles cast with the Native American zigzag sign for water.

From Mountain High…

Most of the water treated at this plant originates in the mountain ranges in seven western states, travels down the Colorado River and flows through Metropolitan's 242-mile Colorado River Aqueduct.  To a lesser degree, water supplied to the plant also comes from Northern California rivers and streams that feed the State Water Project's 444-mile California Aqueduct.

One of the largest filtration plants in the United States, Weymouth delivers up to 520 million gallons per day.  This means the plant cleans enough water to fill the Rose Bowl every four hours. .

Though plant operators must adjust large strategically placed valves, automated systems are designed to regulate water levels and pressures.  In addition, these systems offer precise monitoring and surveillance capabilities to anticipate demands and respond rapidly to emergency water situations, if necessary.

...To Your Kitchen Faucet

Looking at the treatment plants web of pipes, pumps and sophisticated electronic gadgetry, filtration appears to be complicated.  Conventional filtration, however, is surprisingly simple and effective.

The process uses items similar to those found in any home, garden or garage.  Upstream grates and screen catch large debris and plants.  At the treatment plant, coal and sand are used as filter media to remove any particles left in the water then chlorine and ammonia are used to disinfect.

The conventional filtration process includes coagulation.  Here, aluminum sulfate and other chemical additives cling to particles in the water.  These particles stick together and form large particles called floc. The water and floc particles flow into large sedimentation basins that allow the particles to settle to the bottom.

From the basins, water flows through the coal and sand for filtration.  Finally, disinfection kills remaining microorganism to keep the water safe as it travels to the public.  MWD water meets or surpasses all state and federal water quality standards.

Multi-Faceted Sites

Metropolitan is a nationally-recognized leaderin researching major new technologies to meet higher state and federal water quality standards.

Metropolitan has long maintained a strong commitment to water quality. This is evident in the high-tech water quality laboratory the district opened in June 1985.  Scientist, engineers and support staff conduct some 300,000 tests annually to make sure traces of harmful substances are not present in water delivered to consumers.

The Weymouth Legacy

Frank E. Weymouth was Metropolitan's first general manager and chief engineer from 1929 to 1941.  A highly respected dam builder, Weymouth directed some of the best engineering talent in the country to construct MWD's Colorado River Aqueduct and initial distribution system.  This monumental achievement marked the culmination of his career and placed him in the front ranks of America's great engineers.

Frank Weymouth's legacy continues today.  More than 1,800 dedicated Metropolitan employees dedicate themselves to fulfilling Metropolitan’s mission: to provide its service area with adequate and reliable supplies of high-quality water to meet present and future needs in an environmentally and economically responsible way. For its 26 member public agencies, MWD provides almost half of the water used by more than 19 million people in Los Angeles, Orange, San Diego, Riverside, San Bernardino and Ventura counties.

Photo of Weymouth Treatment Plant
F.E. Weymouth Treatment Plant
700 Moreno Ave.
La Verne, CA 91750
Photo of Weymouth Treatment Plant

Page updated: October 23, 2013