Lake Mead - Drought and Water Usage Issues

Drought and Water Usage Issues

Lake Mead's water level has fallen below the drought level (1125 feet above sea level) three times. From 1953 to 1956, the water level fell from 1,200 to 1,085 feet (370 to 331 m). From 1963 to 1965, the water level fell from 1,205 to 1,090 feet (367 to 330 m). Since 2000 through 2008, the water level has dropped from 1215 to 1095. In 2009 the water level rose slightly due to cool winter temperatures and rainfall.

In June 2010, the lake was at 39 percent of its capacity, and on Nov. 30, 2010 it reached 1,081.94 ft (329.78 m), setting a new record monthly low. From mid May 2011 to September 22, 2011, Lake Mead's water elevation increased from 1095.5 feet to 1115.24 feet, and the rivers feeding it were running at 128.06% of the average flow rate for September 22.

Lake Mead draws a majority of its water from snow melt in the Colorado, Wyoming, and Utah Rocky Mountains. Since 2000 the water level has been dropping at a fairly steady rate due to less than average snowfall. As a result, marinas and boat launch ramps have either needed to be moved to another part of the lake or have closed down completely. The Las Vegas Bay Marina and the Lake Mead Marinas were relocated a few years ago to Hemenway Harbor. Overton Marina has been closed due to low levels in the northern part of the Overton Arm, Government Wash, Las Vegas Bay, and Pearce Ferry boat launch ramps have also been closed. The marinas that remain open include Las Vegas Boat Harbor and Lake Mead Marina all sharing Hemenway Harbor/Horsepower Cove, Callville Bay Marina, Echo Bay Marina, and Temple Bar Marina, along with the Boulder Launch Area (former location of the Lake Mead Marina) and the South Cove launch ramp.

Changing rainfall patterns, climate variability, high levels of evaporation, reduced snow melt runoff, and current water use patterns are putting pressure on water management resources at Lake Mead as the population depending on it for water and the Hoover Dam for electricity continues to grow. A 2008 paper in Water Resources Research states that at current usage allocation and projected climate trends, there is a 50% chance that live storage in lakes Mead and Powell will be gone by 2021, and that the reservoir could drop below minimum power pool elevation of 1,050 feet (320 m) as early as 2017. Lake volume is now at the mercy of a cascade of forces that include the fact that it is very likely impossible that the prevailing climate pattern of profound drought will or can change to precipitation surcharge in a time frame shorter than that in which the lake level will fall below the dead storage level of the downstream diversion and hydro-power intake tunnels. However, water levels in the lake rose by more than 30 ft (9.1 m) in 2011 due to a rainy winter and increased snowfall in the Rocky Mountains.

The diversion tunnels, used during construction, are at an elevation at which the flow of the river would continue indefinitely. But they were permanently sealed with massive concrete plugs, isolating them from the remaining sections of the downstream outlet tunnels when the main dam began to be raised and, later when the lake was filled. Today, it is not very likely that they could be removed from the diversion tunnels. And in doing so, it would effectively be the admission that the Hoover Dam project was finished, and had been terminated unsuccessfully. But, Terry Fulp, manager of the federal bureau office for the lower Colorado, disagreed with the paper, saying that global climate models were not sensitive or refined enough to forecast such effects.