The Mono Basin Project

As the country emerged from the Great Depression and entered World War II, Los Angeles voters continued to approve financing for water projects.

The Mono Basin Project was a construction program to obtain a larger and more dependable flow of water to the Los Angeles Aqueduct.  The DWP planned to extend the Los Angeles Aqueduct 105 miles further north, 338 miles from Los Angeles, to take water diverted from the four creeks it had applied for permits for in 1923.  By taking water from Parker, Walker, Lee Vining and Rush creeks, the City would obtain a high quality water supply for 500,000 people.

In 1935 the City applied to the Division of Water Resources to construct Grant Lake Dam to store water from the creeks.  The application was referred to the State Fish and Game Commission for a determination of whether a fishway would be required for the dam.  The Fish and Game Commission determined that no fishway would be required and construction of the dam was approved by the Department of Water Resources.

The City had also finally acquired the reservoir site at Long Valley.  In the DWP’s 1936 application to build a dam there, the same fishway issue was examined and this time a Fish and Game Commission hearing determined that an alternative method of providing fish culture would be provided to compensate for fish losses caused by the construction of both dams.

Following several investigations and studies, the City and the Fish and Game Commission executed the Hot Creek Agreement in 1940.  Under the agreement the City was to provide land, water rights, access roads, and construction funds for the construction of the Hot Creek Fish Hatchery, now probably the most productive fish hatchery in California.

An 11 mile tunnel was drilled through the volcanic Mono Craters to obtain water from Lee Vining, Parker, Walker, and Rush creeks.  It increased the capacity of the aqueduct system 35% to about 300 million gallons per day.  The Long Valley Dam created Crowley Lake Reservoir, the largest reservoir in the Los Angeles water system.

By the time the United States entered World War II, the Mono Basin Project was complete.  Los Angeles swiftly became one of the country’s most important war production centers.  Its heavy manufacturing base continued to diversify, and the population grew with the war effort.

When the war ended, the stage was set for an economic boom with Los Angeles as prime beneficiary.  By 1950, Los Angeles had a population of two million people and had become the fourth largest city in the United States.  The DWP built the Owens River Gorge Hydroelectric Generating Station, the Valley Generating Station, and the Scattergood Generating Station to meet the growing demand for power.

The development of a series of hydroelectric power projects was a natural result of the engineering design of the Los Angeles Aqueduct.  The aqueduct had been designed to deliver water to Los Angeles entirely by gravity, requiring no power for the pumping of water along the route.  Using this natural gravity flow, engineers designed a series of penstocks that dripped the water to power plants located at the bottom of the Gorge.  The force of the water was used to move turbines and create electricity.

During the 1960s there were certain years where the population of California grew as much as 1,500 persons a day.  By the end of the decade one in ten persons in the U.S. lived in California.  Los Angeles was the premier city in the country’s most populous state.

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