The Third Straw

In 2005, faced with the specter of prolonged drought and projected Lake Mead water level declines, the SNWA board of directors approved construction of the so called "Third Straw", a new $812 M intake from Lake Mead that would allow Southern Nevada to physically extract water from the lake at water levels as low as 1000 feet above sea level (Figure 14). Construction of the intake involves boring a 23 foot diameter tunnel through 3 miles of rock, with much of its length beneath one of the Earth's largest man-made reservoirs!

The new intake will intersect the lake at 860 feet above sea level, but will share a pumping station with intake #2, so will only be able to operate at water levels of 1000 feet (the same as for intake #2). The primary purpose of the third straw is to maintain overall system capacity if Lake Mead falls below the 1050 ft water level limit for operation of intake #1. It also will access the deepest parts of Lake Mead, where water quality is highest. The initial plan for the third intake included a separate pumping facility, but was removed to cut costs. It is always possible that the $200 million pumping station and pipelines could be added in the future, though if the Lake Mead water level were to drop much below 1000 feet, there would be much bigger problems throughout the lower Colorado River basin.

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Figure 14. Figure showing projected water levels in Lake Mead as of 2009, with levels shown for federally declared shortage (1075 ft) and operational limits of the SNWA intakes at 1050 and 1000 feet. As of November, 2014, lake level was 1083 feet.
Source: SNWA Water Resource Plan, 2009.