HUZHOU, Zhejiang, Aug. 18 (Xinhua) -- Upward of 8,000 cargo ships and boats have been stranded on a river course connecting Zhejiang Province to Shanghai.

The bottleneck on the Changxing-Huzhou-Shanghai river course, the worst in a decade, extends 40 km.
Zhou Shiquan, chief of the maritime affairs section of Huzhou Ports and Shipping Administration, confirmed Tuesday the build-up on the course, which links Changxing, Huzhou, (both in Zhejiang), and Shanghai, had been closed to shipping for the past 13 days because of safety concerns.
"We opened spillways at Nanxun downstream of the west-east river course at 9 a.m. Tuesday to lower the water level so ships and boats could sail again safely," said Zhou.
Typhoon Morakot early this month roaring across eastern China regions -- including Zhejiang and Fujian provinces and Shanghai --dumped torrential rains, causing flooding on local rivers and lakes.
During the typhoon the water level on the river course rose to a record high of 5.36 meters, but began to fall Aug. 14 when Morakot faded into China's interior. Water levels were at 4.38 meters at 7:30 a.m. Tuesday.
Song Qinghua, another senior official with Huzhou Ports and Shipping Administration, said the level fell to 3.8 meters after an hour of the spillways' opening.
As the course is also connected to flooded Taihu Lake, it was very difficult to say whether the water discharge would be effective long-term, said Song.
The lake's water level was at 4.2 meters at 10 a.m. Tuesday.
"Shipping services can not be resumed until the water level upstream and downstream has a difference of 30 cm," said Song. The water level course is being closely monitored at Nanxun.
The course is 145 km long and carries 80 percent of coal used for generating electricity in Zhejiang, Jiangsu and Shanghai.