|NY Times September 27, 2010
Water Use in Southwest Heads for a Day of Reckoning
By FELICITY BARRINGER
LAKE MEAD NATIONAL RECREATION AREA, Nev. — A once-unthinkable day is
looming on the Colorado River.
Barring a sudden end to the Southwest’s 11-year drought, the
distribution of the river’s dwindling bounty is likely to be reordered
as early as next year because the flow of water cannot keep pace with
the region’s demands.
For the first time, federal estimates issued in August indicate that
Lake Mead, the heart of the lower Colorado basin’s water system —
irrigating lettuce, onions and wheat in reclaimed corners of the Sonoran
Desert, and lawns and golf courses from Las Vegas to Los Angeles — could
drop below a crucial demarcation line of 1,075 feet.
If it does, that will set in motion a temporary distribution plan
approved in 2007 by the seven states with claims to the river and by the
federal Bureau of Reclamation, and water deliveries to Arizona and
Nevada would be reduced.
This could mean more dry lawns, shorter showers and fallow fields in
those states, although conservation efforts might help them adjust to
the cutbacks. California, which has first call on the Colorado River
flows in the lower basin, would not be affected.
But the operating plan also lays out a proposal to prevent Lake Mead
from dropping below the trigger point. It allows water managers to send
40 percent more water than usual downstream to Lake Mead from Lake
Powell in Utah, the river’s other big reservoir, which now contains
about 50 percent more water than Lake Mead.
In that case, the shortage declaration would be avoided and Lake Mead’s
levels restored to 1,100 feet or so.
Lake Powell, fed by rain and snowmelt that create the Colorado and
tributaries, has risen more than 60 feet from a 2004 low because the
upper basin states, Colorado, New Mexico, Wyoming and Utah, do not use
their full allocations. The upper basin provides a minimum annual flow
of 8.23 million acre feet to Arizona, Nevada and California. (An
acre-foot of water is generally considered the amount two families of
four use annually.)
In its August report the Bureau of Reclamation said the extra
replenishment from Lake Powell was the likeliest outcome. Nonetheless,
said Terry Fulp, the bureau’s deputy regional director for the Lower
Colorado Region, it is the first time ever that the bureau has judged a
critical shortage to be remotely possible in the near future.
“We’re approaching the magical line that would trigger shortage,” Mr.
Fulp said. “We have the lowest 11-year average in the 100-year-plus
recorded history of flows on the basin.”
The reservoir is now less than 15 inches above the all-time low of
1,083.2 feet set in 1956.
But back then, while the demand from California farmland was similar, if
not greater, the population was far smaller. Perhaps 9.5 million people
in the three states in the lower Colorado River basin depended on the
supply in the late 1950s; today more than 28 million people do.
The impact of the declining water level is visible in the alkaline
bathtub rings on the reservoir’s walls and the warning lights for
mariners high on its rocky outcroppings. National Park Service employees
have repeatedly moved marinas, chasing the receding waterline.
Adding to water managers’ unease, scientists predict that prolonged
droughts will be more frequent in decades to come as the Southwest’s
climate warms. As Lake Mead’s level drops, Hoover Dam’s capacity to
generate electricity, which, like the Colorado River water, is sent
around the Southwest, diminishes with it. If Lake Mead levels fall to
1,050 feet, it may be impossible to use the dam’s turbines, and the flow
of electricity could cease.
The fretting that dominates today’s discussions about the river
contrasts with the old-style optimism about the Colorado’s plenitude
that has usually prevailed since Hoover Dam — then called Boulder Dam —
was completed 75 years ago, impounding the water from Lake Mead.
The worries have provoked action: cities like Phoenix and Las Vegas have
undertaken extensive conservation programs. Between 2000 and 2009,
Phoenix’s average per-capita daily household use has dropped almost 20
percent; Las Vegas’s has dropped 21.3 percent.
Nonetheless, “if the river flow continues downward and we can’t build
back up supply, Las Vegas is in big trouble,” Pat Mulroy, general
manager of the Southern Nevada Water Authority, said in an interview.
While Las Vegas is one of the Colorado River’s smaller clients — it
consumes 2 percent of the river’s allocated deliveries— the city relies
on Lake Mead for 90 percent of its water supply. From 2002 to 2009, the
metropolitan area’s population mushroomed by nearly 40 percent, to 1.9
million from 1.37 million.
In response to the population boom and the drought, which began in 1999,
the authority began an aggressive effort to encourage water conservation
Now it is expanding its options: it is tunneling under the bottom of
Lake Mead to install a third intake valve that could continue operating
until lake levels dropped below 1,000 feet.
Saddle Island, the construction staging site on the reservoir, looks
like an abstract painting, its dusty russet ground covered with
interlacing segments of the 2,500 concrete rings that will make up the
Ms. Mulroy has also pushed aggressively for pipelines to carry distant
groundwater to the Las Vegas area; most contentious is a planned
285-mile pipeline that would cross the state diagonally and take
groundwater from the Snake Valley, on the Nevada-Utah border, to Las Vegas.
The authority has also spent about $147 million on a program to
encourage homeowners and businesses to eliminate their lawns in favor of
the rock, grass and cactus landscaping known as xeriscaping. More than
70 percent of household water usage is attributed to outdoor use, Ms.
Residents can now water their yards only three days a week, before 11
a.m. and after 7 p.m., and the restrictions are to tighten this winter.
Dolores Cormier, 82, who lives on Monterrey Avenue on the southern side
of Las Vegas, reconfigured her front and side lawns, installing a rocky
cover and drip irrigation. Under a water authority program known as
Water Smart Landscapes (colloquially, Cash for Grass), she has received
$2,689 in utility subsidies that will offset the $5,600 or so she said
the xeriscaping cost her.
She is pleased with the new look but said her average monthly water bill
of $45 or so has yet to decline, perhaps because she still tends grass
in her small backyard. “I need some lawn,” she confessed.
If the 1,075 level is broken at Lake Mead next year, more drastic
conservation measures will be needed, officials warn.
“We have a very finite resource and demand which increases and enlarges
every day,” said John A. Zebre, a Wyoming lawyer and the president of
the Colorado River Water Users Association.
“The problem is always going to be there,” he said. “Everything is
driven by that problem.”