Lake Mead falls below First Water Intake

 

photo from SNWA 

The Southern Nevada Water Authority announced late last week that after 22 years of drought within the basin, the level of Lake Mead fell below 1,050 feet above sea level. Lake Mead drinking water Intake #1, the topmost pumping station is now above the surface level of the Colorado River reservoir behind Hoover Dam. The intake is the uppermost of three in the lake formed behind the Hoover Dam that provides Las Vegas with 90% of its drinking water supply. 

from Bureau of Reclamation

In their announcement the Southern Nevada Water Authority pointed out that its Low Lake Level Pumping Station #3 installed in anticipation of this happening is operational. Southern Nevada Water Authority constructed the third drinking water intake capable of drawing Colorado River water at lake Mead at elevations below 1,000 feet. Intake #3 ensures Southern Nevada’s access to its primary water supply as lake levels continue to decline due to the drought conditions. The problem is the level of lake Mead keeps falling and despite significant conservation efforts there is no longer enough water to supply the region. There is a time limit on how much longer there will be water.

There has been a drought in the Colorado River Basin for the past 22 years. This combined with higher temperatures has led to what some are calling aridification of the region. Lake Mead has seen more than 130-foot drop in the water level since the turn of the century. The annual flow of the Colorado River is estimated to have fallen about 20% in the 21st Century compared to the 20th Century due to both rising temperatures and drought. The region is in trouble.

from SNWA

The 1922 Colorado River Compact, negotiated by the seven basin states (Colorado, Nevada, Utah, New Mexico, Wyoming, Arizona, California) divided the Colorado River basin into upper and lower portions, allotted the Colorado River’s water on the basis of territory. The allocation of water rights based on territory allowed development to proceed in the lower basin (essentially California) while safeguarding supplies for the upper basin. Then, as now, California's growth and demand for water was viewed with concern by her neighbors.

The problem now is that the allocations promised under the Colorado Compact was based on an expectation that the river's average flow was 16.4 million acre feet per year  and ignored the needs of nature and the tribes. Subsequent studies: however, have concluded that the long-term average water flow of the Colorado is less. In addition, according to the University of Arizona, records going back to paleolithic times (more than 10,000 years ago) indicates periods of mega-droughts in the distant past. 

Now with more than twenty dry years, the reservoirs have dwindled to their lowest levels recorded. Allotted shares of water in the basin exceeds the average long-term (1906 through 2018) historical natural flow of under 16.0 million acre-feet. To date, the imbalance has been managed, and demands largely met by slowly using up the considerable amount of reservoir storage capacity in the Colorado River system-  Lake Powell and Lake Mead that once held approximately 60 million acre-feet (nearly 4 years of average natural flow of the river). It was assumed that drought years would be followed by wet year to refill the reservoirs. That has not happened recently, the last time the reservoirs filled was 1983. The basin is in its 22nd year of drought and the true existential crisis for Las Vegas looms just over the horizon. For without water there is no life.