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.
Figure 14 shows the elevation of Lake Mead on the y-axis versus the year on the x-axis including different water conservation projects. The important take home from this figure is that as we near 2022 we see that water levels drop. But as different conservation projects (in green, pink, purple, etc.) grow, the rate at which water levels drop decreases. In the time series, the thick dashed line represents the hypothetical elevation of Lake Mead due without conservation projects, while the solid black line represents the actual water level. Although water level is still dropping as of 2022, conservation efforts play a large role in stabilizing Lake Mead water levels.