The waters of the mighty Danube are so low that dozens of cargo ships are stuck, stranded in ghostly fog or wedged into sand banks on what is normally one of eastern Europe's busiest transport routes.

A lack of rain has triggered the worst drought in decades for this time of year, dropping river levels to record lows and sounding an alarm in parts of central and eastern Europe. Power supplies are running low in Serbia, drinking water shortages have hit Bosnia, and crop production is in jeopardy in Romania, Bulgaria and Hungary. The Czech Republic is at its driest since records began in 1775.

Meteorologists say they are not sure why the region has had far less rain than average since August — but they don't see any more coming quickly. That is bad news for shipping companies that are already reporting big losses.

"This is a disaster," said Branko Savic, the manager of a privately owned Danube shipping company in Serbia that he says is operating at only a third of its capacity. "Traffic on the Danube is practically nonexistent. . . We are in dire need of enormous amounts of water, rain, or melting snow in order to better the situation."

"In my many years of experience as a boat captain, I don't remember a drought as harsh as this one," said Anton Balasz, whose ship is among those stuck where exposed sand banks are preventing boats from passing.

In Bosnia, drinking water restrictions have been introduced at night in Sarajevo and other cities. "The Bosna river is so low, you can walk from one bank to another," said Emir Emric, a fisherman. "People catch fish with bare hands — and not only any fish — but 20-kilogram (44-pound) catfish."

The current level of the river along the Bulgarian bank is at its lowest since 1941, and shipping on large stretches of the river has ground to a halt, according to the Bulgarian Executive Agency for Exploration and Maintenance of the Danube River.

In Romania, officials say that though the country had a bumper wheat harvest this year, the drought looks set to severely damage next year's production. "If the drought continues, the wheat crop will be down by at least 20 percent," said Marcel Cucu, the spokesman for the Romanian League of Agriculture Producers Associations.