LAS VEGAS (KLAS) — For the first time since Lake Mead was filled in the 1930s, it is now below 30% full.
According to the Bureau of Reclamation’s weekly report for the Lower Colorado River water supply, Lake Mead’s at 29% capacity.
Upriver Lake Powell is currently at 27% capacity.
As of June 7, the Bureau of Reclamation measured Lake Mead’s water level at 1,046.53 feet above sea level. This means the lake is now 182.6 feet below its maximum depth.
The last time Lake Mead was at its maximum depth, or ‘full pool’ was the summer of 1983. Since then the depletion of Lake Mead water has continued on and off over the last 39 years, and increased dramatically over the last 20 years during a historic drought and increased growth in the southwest United States.
MEASURING THE CAPACITY OF LAKE MEAD
In 1935, the BOR and Soil Conservation Service undertook a mapping program to calculate the storage capacity of the nearly formed Lake Mead. As water began to back up behind the dam, surveyors recorded measurements of the ground surface based on stereoscopic aerial photographs and water soundings (Brown 1941).Source: nps.gov
This study produced calculations of an estimated capacity of over 31 million acre-feet of water at an elevation of 1,221.4 feet. Since 1935, sedimentation has decreased the capacity of the reservoir and a number of subsequent studies have been carried out to determine its current storage capacity as well as to model the lake’s economic life into the future.
Subsequent ground surface measurements include bathymetric studies conducted from 1948 to 1949,1963 to 1964, and in 2001. In late 2009, BOR acquired LiDAR (combination of Light and Radar) data for elevations of emerging shorelines, which was meant to complement 2001 side-scan sonar data.
The LiDAR and sonar data, which cover elevations of the ground surface at and below 1,230 feet elevation, have been obtained by Lake Mead NRA from BOR under a data sharing agreement and used to estimate lake capacity.