In what year did the Metropolitan Water District of Southern California complete the Colorado River Aqueduct?

The Metropolitan Water District of Southern California completed the Colorado River Aqueduct in 1941, making this the correct answer. This significant infrastructure project was designed to transport water from the Colorado River to the rapidly growing urban areas of Southern California. The completion marked a crucial development in the region's efforts to secure a reliable water supply, particularly as population demands increased in the early 20th century.

In this period of expansion, the aqueduct provided a critical source of water that helped support agriculture, industry, and growing urban communities. The construction of the aqueduct itself, which began in the 1920s, was a monumental engineering feat, involving various challenges such as geological difficulties and the need to construct extensive pipelines and reservoirs.

The other years listed do not correspond to the completion date of the Colorado River Aqueduct. The project was indeed under construction in the years leading up to 1941, but the actual completion that allowed for water delivery occurred in that specific year, underscoring its importance in California's water history.