An accumulation of tree branches, weeds and junk has formed a layer on the surface of a waterway in northeast China's flood-devastated Jilin Province, blocking the flow of water under a bridge and threatening a downstream dam, officials said Tuesday.

The accumulation covers an area of 15,000 square meters and is up to one meter thick in places. It is located near the Yunfeng Dam in Baishan City.

Workers are racing to clear the accumulation amid fears the jammed bridge might collapse if another flood hits before the accumulation is removed.

"We have collected 40 trucks of the trash, but the remaining trash might fill another 200 trucks," said Wang Yong, a police officer in charge of the clean-up operation.

It may take another five days to finish clearing the waterway on the upper reaches of the Yalu River, Wang said.

Wang said the Yunfeng Dam is operating at full capacity to avoid overflowing, with 5,000 cubic meters of water per second flowing through its five flood gates.

Officials fear if the bridge collapses, the debris and the accumulation might flow downstream to the dam and block its flood gates.

Jilin has been ravaged by floods this summer. In the last two months, over 120 people have been killed or listed as missing.

Aggravating the situation, another round of heavy rain is forecast to pound the already-flooded areas in Jilin from late Tuesday until Friday.