Archive for the 'climate change' Category

“The story of the Hoover Dam in the 21st century is more embattled than triumphant, largely due to a seven-year drought that has stressed the ability of the Bureau’s infrastructure to deliver the water promised in the Colorado River Compact. At the time of our visit, Lake Mead was at 45 percent of capacity, and with below normal runoff forecast again in 2010, the lake is projected to drop another 20 feet by the end of the summer. That would put it dangerously close to the 1075-foot elevation level at which water delivery cutbacks to the lower basin states would be triggered. These cutbacks would likely cause interstate and international tensions, as Arizona, California, Nevada, and Mexico posture in case of further shortages. The decrease in water level also reduces Hoover’s power generation, which would be cut more dramatically if the lake falls below the 1050-foot watermark.

“While Hoover Dam remains a critical linchpin in the Southwest’s water and power supply, it’s clear that grand 20th-century infrastructure alone will not be enough to solve the region’s water resource challenges in the 21st century, for a number of reasons.

“First of all, it’s highly likely that the water “annuity” being withdrawn from the Colorado River system is greater than the long-term average water restored to the system in the form or rainfall and snowmelt. Between the 15 million acre-feet of water allocated to the basin states, the 1.5 million acre-feet promised to Mexico, and the 2 million acre-feet of evaporation in the basin every year, the total water withdrawn from the Colorado every year is 18.5 million acre-feet. However, the latest models show that the long-term average runoff in the Colorado basin every year is likely closer to 14 or 15 million acre-feet. In other words, the hydrological account is being overdrawn every year, and, sooner or later, there may be no water left to take.”

read more: Stanford.edu