CLAREMONT, Calif. (CBSLA) — About one million residents from eastern Los Angeles into San Bernardino counties are being asked to cut down their water use this week due to repairs which will shut down a major pipeline.

The closure of the 30-mile-long Rialto Pipeline, which runs from San Dimas to San Bernardino, began Monday and is expected to last through Saturday, April 28.

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The closure is affecting the Inland Empire communities of La Verne, Fontana, Montclair, Claremont, Upland, Chino Hills, Chino, Ontario and Rancho Cucamonga. During the closure, residents in those areas will primarily have to rely on local water supplies as opposed to imported water, the Metropolitan Water District (MWD) reports.

Most of the Rialto Pipeline is owned by the MWD, while a small portion is owned by the California state Department of Water Resources. It is the portion owned by the state which is undergoing repairs.

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Residents are asked to avoid using washing machines and dishwashers, to keep showers short, avoid watering lawns, and avoid filling swimming pools. For more information, click here.

Officials have only had since January to plan for the closure, whereas most such shutdowns are scheduled a year in advance.

Along with MWD, the Inland Empire Utilities Agency and Three Valleys Municipal Water District are also served by the Rialto Pipeline. The IEUA receives all its imported water from Rialto, while Three Valleys also has access to an alternative MWD pipeline.

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The Rialto Pipeline pumps in 450,000 gallons of water per minute.