There are varying storage capacity elevations for water levels at Lake Mead. The U.S. Bureau of Reclamation (BOR) measures the reservoir’s storage and operational capacities at the following elevations:
Lake Mead Operational Levels
Description
Elevation (ft)
Top of Dam - Maximum designed water-surface elevation
1,229.0
Full Pool - Operational Capacity
1,219.0
SNWA Intake No. 1 - Dam intake tower's upper gates
1,050.0
Inactive Pool - Minimum elevation for power generatiom
950.0
Dead Pool - Lowest water outlet, Dam intake towers' lower gates
895.0
Dead Storage- No water can be released downstream of Hoover Dam
849.0
When BOR releases weekly and monthly hydrology data, they are reporting on what is commonly known as “live storage capacity,” which ranges in elevations from 895 feet to 1,219.6 feet. Water elevations ranging from 1,219.6 feet up to 1,229.0 feet is referred to as “full pool” and represents the Dam’s exclusive flood control space, as the Colorado River naturally fluctuates over time.
Water elevation of 950.0 feet, or 8% of live capacity, is the minimum level of water needed to generate power at Hoover Dam. Water elevations between 950.0 feet to 895.0 feet is considered “inactive pool” because water can be released from the dam downstream but does not generate hydropower. Water capacity at 895.0 feet elevation is considered “dead pool,” which is when downstream releases from Hoover Dam are no longer possible.
Measuring the Capacity of Lake Mead
In 1935, BOR and the Soil Conservation Service mapped the nearly formed Lake Mead’s topography in order to calculate the reservoir’s storage capacity. This study resulted in an estimated capacity of over 31 million acre-feet of water at an elevation of 1,221.4 feet.
Since 1935, sedimentation build up and shifts due to river flow over time has decreased the capacity of the reservoir.
A number of subsequent studies have been conducted to determine its current storage capacity and to support long-term planning and modeling for the lake’s operational and economic 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 at and below 1,230 feet elevation, which were published in 2011.
The most recent sedimentation study indicated that the capacity of Lake Mead increased between 1964 and 2001 because the soil at the bottom of the lake had compacted over time. BOR is currently working on an updated bathymetry study at Lake Mohave at the southern end of the Lake Mead National Recreation Area.
Area and Capacity of Lake Mead (2010)
Location
Elevation
(Feet)
Area of Lake
(Acres)
Total Capacity of Lake
(Acre-feet)
Capacity of Lake
(Acre-feet)1
Maximum designed water-surface elevation
1229.0
162,916
30,167,000
27,620,000
Crest of drum gates on spillway (raised)
1221.4
158,488
28,946,000
26,399,000
Operational capacity
1219.6
157,466
28,667,000
26,120,000
Permanent crest of spillway sill
1205.4
148,853
26,483,000
23,936,000
Intake tower, upper gates
1050.0
72,208
10,230,000
7,683,000
Inactive Pool
950.0
42,869
4,553,000
2,006,000
Intake tower, lower cylinder gate entrance liners
895.0
30,270
2,547,000
0
From U.S. Bureau of Reclamation (2011) 1Reclamation reports live capacity and percent of live capacity in all public documentation.
Bureau of Reclamation
Bureau of Reclamation
Bureau of Reclamation
Bureau of Reclamation end of year water elevation levels (in feet) for Lake Mead from 1935 to 2022 as indicated by the blue line.
Graph/Bureau of Reclamation
Bureau of Reclamation projections of the water elevation levels for Lake Mead through July 2024 (red line). Historic lake levels from August 2021 to June 2022 are shown on the left side of the graph via the black line. (These projections came from the August 2022 study.)
Bureau of Reclamation
References & Resources
Mapping the Floor of Lake Mead (Nevada and Arizona): Preliminary Discussion and GIS Data Release U.S. Geological Survey Open File Report 03-320, 2003 https://pubs.usgs.gov/of/2003/of03-320/
Mapping Lake Mead Carl B. Brown, Geophysical Review, Vol. 31, No. 3, pp. 385-405, July 1941
Bureau of Reclamation , Lower Colorado Regional Office GIS Group, The 2001 Lake Mead Bathymetry Study. September 2003
Bureau of Reclamation, Lower Colorado Regional Office, Lake Mead Area and Capacity Tables. September 2011
Lara, J. M. and Sanders, J. I. The 1963-64 Lake Mead Survey. Bureau of Reclamation, Sedimentation and River Hydraulics Group. Denver, Colorado. Bureau of Reclamation REC-OCE-70-21
