Severe Drought Could Threaten Power Supply in West for Years to Come: WSJ

Widespread drought conditions throughout the Southwest over the past 20 years have led to a more than 130-foot drop in the water level at Lake Mead since 2000.

Lake Mead water elevation, change from previous July

Elevation rose

Elevation declined

1,250

 feet

Maximum elevation

1,200

1,150

1,100

1,050

1,000

Minimum power pool

950

900

2000

’05

’10

’15

’20

Elevation rose

Elevation declined

1,250

 feet

Maximum elevation

1,200

1,150

1,100

1,050

1,000

Minimum power pool

950

900

2000

’05

’10

’15

’20

Elevation rose

Elevation declined

1,250

 feet

Maximum elevation

1,200

1,150

1,100

1,050

1,000

Minimum power pool

950

900

2000

’05

’10

’15

’20

Source: Bureau of Reclamation

The Bureau of Reclamation’s latest projections, from July, show the lake’s water level falling another 31 ft., to 1,037 ft., by June 2023.

For dams to produce power, they rely on the immense pressure created by the body of water they are blocking. As water levels go down, less pressure is exerted and the dams in turn produce less hydroelectric energy, which means the dam can produce less power.

Important Operating Elevations at the Hoover Dam

Intake

tower

1,229 ft.

Maximum pool elevation

1,200

Approximate elevation

in 2000

1,068

Approximate

current elevation

Minimum pool

for power generation

950

Lake mead

Intake

tower

1,229 ft.

Maximum

pool elevation

1,200

Approximate

elevation in 2000

1,068

Approximate

current elevation

950

Minimum pool

for power generation

Lake mead

Intake

tower

1,229 ft.

Maximum

pool elevation

1,200

Approximate

elevation in 2000

1,068

Approximate

current elevation

950

Minimum pool

for power generation

Lake mead

Note: Elevation locations are approximate.

Photo: Bureau of Reclamation (1935)
Source: Bureau of Reclamation

While 1,068 ft. of depth in a body of water as large as Lake Mead seems massive, every foot of water lost equates to about six megawatts less power generated in a year, according to Patti Aaron, public affairs officer at the U.S. Bureau of Reclamation, which operates and maintains the power plant. Six megawatts roughly translates to the power consumed by 800 homes.

If the water level drops 118 ft. from July’s level, to 950 ft., it would fall below the turbines and the dam must shut down, Ms. Aaron said.

The power declines are significant. At 1,200 ft. water elevation—where it was in the year 2000, when water levels were among the dam’s highest levels—the dam can power up to 450,000 homes. At the current elevation, that figure falls to 350,000.

Homes able to be powered by the Hoover Dam at different power capacities

Metropolitan Water District of Southern California

(includes portions of Los Angeles, Orange, Riverside,

San Bernadino, San Diego and Ventura counties)

1 = 1,000

homes

At 1,200 ft. elevation,

producing 2,074

megawatts of power

At current 1,068 ft.

elevation, producing

1,567 megawatts

of power

Nevada

Arizona

Los Angeles

Southern California Edison Co.

(includes portions of Fresno, Imperial, Inyo, Kern, Kings, Los Angeles, Madera, Mono,

Orange, Riverside, San Bernadino, Santa Barbara, Tuolumne, Tulare and Ventura counties)

Riverside, Calif.

Boulder City, Nev.

Vernon, Calif.

Glendale, Calif.

Burbank, Calif.

Pasadena, Calif.

Anaheim, Calif.

At 1,200 ft. elevation,

producing 2,074

megawatts of power

At current 1,068 ft.

elevation, producing

1,567 megawatts

of power

Metropolitan Water District of Southern California

(includes portions of Los Angeles,

Orange, Riverside, San Bernadino,

San Diego and Ventura counties)

1 = 1,000

homes

Nevada

Arizona

Los Angeles

Southern California Edison Co.

(includes portions of Fresno, Imperial, Inyo, Kern,

Kings, Los Angeles, Madera, Mono, Orange, Riverside,

San Bernadino, Santa Barbara, Tuolumne, Tulare

and Ventura counties)

Riverside, Calif.

Boulder City, Nev.

Glendale, Calif.

Vernon, Calif.

Burbank, Calif.

Pasadena, Calif.

Anaheim, Calif.

At 1,200 ft. elevation, producing 2,074

megawatts of power

At current 1,068 ft. elevation, producing

1,567 megawatts of power

Metropolitan Water District

of Southern California

(includes portions of Los Angeles,

Orange, Riverside, San Bernadino,

San Diego and Ventura counties)

1 = 1,000

homes

Nevada

Arizona

Los Angeles

Southern California Edison Co. (includes

portions of Fresno, Imperial, Inyo, Kern, Kings,

Los Angeles, Madera, Mono, Orange,

Riverside, San Bernadino, Santa Barbara,

Tuolumne, Tulare and Ventura counties)

Riverside, Calif.

Boulder City, Nev.

Glendale, Calif.

Vernon, Calif.

Burbank, Calif.

Pasadena, Calif.

Anaheim, Calif.

Note: Includes areas receiving power for more than 1,000 homes at 1,200 ft. water elevation. Home equivalencies represent homes powered for a year if water elevation held for a year.

Sources: Bureau of Reclamation (power allocations); Patti Aaron, Bureau of Reclamation (home equivalencies); the companies (counties covered)

The Hoover Dam is one of the nation’s largest hydroelectric facilities. About 23% of its power output serves Nevada, 19% serves Arizona, and most of the remainder serves Southern California.

The California Independent System Operator, or Caiso, which oversees the state’s power grid, last summer resorted to rolling blackouts during a West-wide heat wave that constrained the state’s ability to import electricity. The supply crunch was most acute in the evening, after solar production declined.