Ice run was spotted at the outlet of the Yellow River on Monday, about half a month later than usual, according to local officials.
The Yellow River Shandong Bureau, noting that the ice run was just beginning to appear, didn't disclose how long of the river was affected.
Ice formations at the lower reaches of the Yellow River usually persist from December to February.
Severe ice run would cause removal of float bridges across the river in the region, said local sources.
A 184-kilometer ice run was sighted on Friday in the upper section of the Yellow Rive in an area flowing through the northwestern Ningxia Hui Autonomous Region.
Sections of the Yellow River freeze and thaw at different times. When an ice run flows to a frozen section, it can be blocked. If the blockage persists, water levels may rise and cause floods and dam bursts, threatening lives and property.
Flood control authorities along the 5,464-km Yellow River are conducting round-the-clock surveillance against a possible ice flood of the river.
The Yellow River, second longest in China, originates in Qinghai Province in the northwest and flows through Gansu, Ningxia, Inner Mongolia, Shaanxi, Shanxi and Henan, before emptying from Shandong into the Bohai Sea.
(Xinhua News Agency January 2, 2008)