As they guide barges and passenger ferries beneath Budapest's stately bridges, Danube riverboat captains are again on the lookout for Hunger Rock.
The low-lying boulder, normally hidden just beneath the brown surface near Petofi Bridge, is only visible in times of prolonged drought. In early September, as some parts of the river fell to the lowest levels in more than a century, Hunger Rock broke the surface.
"Never in my life have I seen the river this low," says Danail Nedialkov, general director of the Danube Commission, the Budapest-based body responsible for navigation on the river, which passes through 10 countries on its 1,800-mile journey from Germany's Black Forest to the Black Sea. Hundreds of ships and barges have become stranded, unable to pass shallow stretches of Europe's second-longest river.
The Cernavoda Nuclear Power Plant in Romania, which draws its cooling water from the river, was forced to shut down for nearly a month. For days in early September, illegal immigrants were spotted wading across the shrunken river, from Bulgaria to Romania. The falling water has exposed World War II bombs in Budapest, tanks in Croatia, and sunken German ships in the lower Danube.
Water levels have dropped in the Sava River in Croatia, as well as the Rhine, which connects to the Danube by a navigation canal. The river is six feet shallower than normal in some places, further complicating riverborne shipping. Passengers using the twice-daily hydrofoil service between Vienna and Budapest now travel on small 44-passenger vessels instead of the usual 66-passenger ones because of concerns that the larger vessels might run aground in the shallows near the Slovak capital, Bratislava.
River levels rose modestly in mid-September after it rained in Germany. Now, however, the water is falling again.
"Here in Budapest the river has not been this low since 1947," says Janos Litvai, managing director of inland shipping at MAHART, the Hungarian shipping company, which has 15 ships stranded by low water and expects its losses from the drought to exceed $1 million. Losses to Croatian shipping have been estimated in excess of $870,000, while Bulgaria's ports and state shipping company lost an estimated $600,000 in August alone.
Mr. Nedialkov, a native of Ruse, Bulgaria, who captained ships on the river for 20 years before joining the Danube Commission, says he was shocked by the change in the river's appearance.
"I looked down and there was this little river there instead of the great Danube," he recalls. The river in that area had gone from half a mile wide and 13 feet deep to 650 yards wide and 4 feet deep.
Hungarians have also witnessed a substantial contraction of Lake Balaton, Central Europe's largest lake and a popular summer spot 90 miles southwest of Budapest. In some places, the water has retreated 150 to 300 feet from shore, forcing bathers to trudge through the mud to swim. Residents say the lake has been noticeably shrinking for the past four years.
Janos Zlinszky of the Regional Environmental Center for Central and Eastern Europe in Szentendre, Hungary says much of the Danube's troubles are due to reduced snowfall and higher average temperatures in the Alps, whose streams feed many of the Danube's tributaries.
"The glaciers are shrinking more and more every year, and there is much less snowpack to feed the rivers," he notes. "The situation in the Danube is very much connected to climate change."
The low water levels also threaten the ecologically sensitive Danube delta, a wetlands region at the mouth of the river on the Romanian-Ukrainian border. The delta, which provides a nesting habitat for birds and nursery grounds for many types of Black Sea fish and crustaceans, suffered considerable damage from an ill-conceived communist-era development project in the 1980s. Romanian dictator Nicolae Ceausescu ordered many sections drained in a failed attempt to convert the region to rice fields.
Environmentalists are concerned that the low water levels will cause further harm to the ecosystem.
Mr. Nedialkov agrees that low water levels are linked to reduced snowfall in the mountains, but says it's impossible to say whether this is connected with global warming. "There's not enough rain in the summer or snow in the winter," he says. "What can I say, it's in God's hands."