In Israel, the receding shores
of Lake Tiberias—also known as the Sea of Galilee—sometimes
allow mere mortals to walk where the water once was.
Thousands of lakes in China have disappeared entirely.
The diversion of river water in India and Pakistan that allowed
for a doubling of irrigated area over the last four decades has
depleted many lakes.
All told, more than half of the world’s five million lakes
For more than 4,000 years, farmers have diverted river water
for crops in dry areas and dry seasons, reducing the flow into
nearby lakes and seas. Over the last half-century world water
use has tripled, expanding faster than population. Today irrigation
accounts for two- thirds of global water use. With the advent
of diesel and electrically driven pumps, groundwater extraction
in some areas has exceeded recharge from precipitation, also
causing water tables and lake levels to fall.
Nestled among deserts, the five-million-year-old Aral Sea is
one of the world’s most ancient lakes. As recently as the
early 1960s, it covered some 66,000 square kilometers (25,483
square miles) and held 1,000 cubic kilometers (264 trillion gallons)
of water. Two rivers, the Amu Darya and Syr Darya, fed the lake
with some 65 cubic kilometers of water each year.
Today, however, irrigation of vast fields of cotton has drained
the rivers, reducing the annual inflow to only 1.5 cubic kilometers.
As a result the Aral has lost four-fifths of its volume and split
into two sections. The shoreline of the Aral Sea has receded
by up to 250 kilometers, leaving behind a salty desert.
The United Nations estimates that every day 200,000 tons of
salt and sand containing residual agricultural chemicals
metals from the uncovered seabed are carried by the wind and
dumped on farmland within a 300-kilometer radius, destroying
pastures and arable land. The pollution of air, land, and water
has left a legacy of diseases such as cancer, cholera, and typhus.
The once-prolific fishery has been destroyed.
Growing water demands are causing other lakes around the globe
to vanish. (See http://www.earth-policy.org/Updates/2005/Update47_data.htm
for additional examples and data.) Irrigation withdrawals from
the waters that feed Africa's Lake Chad quadrupled between 1983
and 1994. Water consumption, combined with low rainfall levels
since the 1960s, has shrunk the lake by 95 percent, from 25,000
square kilometers to 1,350 square kilometers, over the past 35
Overpumping groundwater in China's Hebei province has lowered
the water table, resulting in the loss of 969 of the province's
1,052 lakes. Madoi County in northwest China's Qinhai province,
the first through which the main stream of the Yellow River flows,
once had 4,077 lakes. Over the past 20 years, more than half
In 1998, China’s largest river, the Yangtze, experienced
devastating flooding, taking the lives of 3,600 people and wreaking
more than $30 billion in damages. The floods were largely attributed
to the cutting of forests and the loss of more than 13,000 square
kilometers of lake area along the Yangtze’s middle and
lower reaches. Prior to the flooding, some 800 lakes had disappeared
entirely, depriving the basin of needed water storage capacity
and flood protection. Following the floods, the Chinese government
pledged action to restore both forests and lakes.
Tonle Sap in Cambodia, Southeast Asia’s largest freshwater
lake, supports one of the world’s largest inland fisheries.
It has long provided flood protection, fluctuating in volume
according to rainfall and climate. Eroding deforested and farmed
land is silting up the lake and reducing its storage capacity,
ultimately increasing the region’s vulnerability to the
opposing extremes of flooding and water scarcity.
The Hamoun Lakes and nearby wetlands in Iran and Afghanistan's
Sistan Basin are similarly losing their ability to mitigate floods
as they are drying from the damming of the Helmand River and
years of drought.
Mono Lake, North America’s oldest, dating back some 760,000
years, is an important feeding stop for migrating birds, especially
as southern California has lost over 90 percent of its wetlands.
Since the first diversions of its tributaries to quench the thirst
of growing Los Angeles in 1941, the lake has contracted dramatically,
with water level dropping by 11 meters (34 feet) and volume down
40 percent. As a result, its salinity has jumped to three times
that of the ocean--far too salty to sustain most fish. The lake
likely would have died completely had locals not intervened and
defeated Los Angeles in a legal battle over keeping water for
Mexico's largest lake, Chapala, is the primary source of water
for Guadalajara’s growing population of five million. This
lake’s long-term decline began in the 1970s, corresponding
with increased agricultural development in the Río Lerma
watershed. Since then, the lake has lost more than 80 percent
of its water. Between 1986 and 2001, Chapala shrank in size from
1,048 to 812 square kilometers. Climbing municipal and industrial
water demands now exceed the sustainable supply by 40 percent.
The lake’s contraction has come at the expense of several
fish species and potentially presages a change in the mild climate
that the water supported.
Lakes are not only being drained dry; they also are dying
from contamination. Farm wastes, sewage, and nitrogen fallout
fossil-fuel burning fertilize lakes, causing excess algae and
plant growth that depletes water oxygen levels and kills aquatic
animal life. Such eutrophication plagues more than half the
lakes in Europe and Asia, 41 percent of those in South
28 percent in North America. Acid precipitation, largely from
fossil-fuel burning emissions, is killing thousand of lakes.
An estimated 120,000 square kilometers of lakes in Norway
are acidified to the point where fish stocks have crashed.
has some 4,000 acidified lakes. In Canada, some 14,000 lakes
are severely acidified. The U.S. Environmental Protection
Agency estimates that some 70 percent of sensitive lakes
in New York's
Adirondack Mountains are at risk of periodic acidification,
and that without further reductions in sulfur dioxide emissions,
the rate of acidification will increase by half or more.
A survey of remote mountain lakes throughout Europe found
that even lakes far from human development were acidified
and nitrogen deposition and that virtually all were contaminated
by heavy metals (such as mercury, lead, and cadmium) and
fly ash particles.
Rising global temperatures are predicted to increase average
lake temperatures by 2-3 degrees Celsius (3.6-5.4 degrees
Fahrenheit) over the next 50 years. Unfortunately, as
water warms, its
natural purification processes can slow down. Climate-related
in water chemistry and stratification can lead to fish
losses, as is already being seen in East Africa's Lake
More than two billion people live in countries
with chronic water stress. Many of the world's people, especially
in developing countries, depend on fish for protein.
are not only
reservoirs of fresh water and a source of food, but
also important habitats
for aquatic organisms and waterfowl. Lakes reduce flood
damage, moderate climate, and recharge groundwater
also offer transportation and recreational opportunities
With all the benefits that we derive from healthy
lakes, we cannot afford to let them disappear.
Additional data and information sources at www.earth-policy.org
or contact firstname.lastname@example.org.