CHENGDU -- The water level in the Yangtze River's middle and lower reaches continues to fall and is threatening navigation along the waterway, local sources said on Friday.

With drought conditions and high temperatures, the Yangtze River's water level in Hankou City, central China's Hubei Province, fell to 17.07 meters on Friday as opposed to a norm of 21 to 22 meters for this time of the year, said a source with the provincial flood control and drought relief headquarters.

"The level is the second lowest since hydrologic records for this section of the river began in 1865," said the source.

The low water level has threatened navigation in many parts of the lower and middle reaches of the river -- Taipingkou and Lujiahe in Hubei, for example, or Fujiangsha in east China's Jiangsu Province, said Wei Zhigang, deputy director of the Yangtze River Waterway Bureau.

Four dredging ships are working around-the-clock in shallow areas along the waterway to ensure normal navigation, he said.

Navigation at Taipingkou of Shashi City in Hubei Province is banned temporarily from 8 a.m. to 12 a.m. each day in order to carry out dredging work, said Wei.

The worst drought since 1951 hit southwest China's Sichuan Province and Chongqing Municipality this summer.

Sichuan and Chongqing have experienced between 30 and 50 high temperature days, making it the hottest period since meteorological records began, said the China Meteorological Administration.

Twenty-eight counties or districts of Chongqing had temperatures in excess of 40 degrees Celsius this summer with certain areas as high as 44.5 degrees Celsius, said the administration.

Though the number of drought-affected counties has been reduced from 112 to 41 thanks to recent rainfall in Sichuan Province, the central and eastern parts of the province are still plagued by drought, said the provincial meteorological observatory.

Clear weather with temperatures above 33 degrees Celsius is forecast to hover over the east and south of the province in the next four days, which may worsen the drought situation in these areas, according to the observatory.

In east China's Jiangxi Province, 560,000 people face a drinking water shortage and 210,000 hectares of crops have been affected by the drought, according to the provincial flood control and drought relief headquarters.

The drought has also dried up 37 reservoirs in Jiangxi and caused the water level of the Poyang Lake, China's largest freshwater lake, to fall by 3.25 meters since August 9 to 11.25 meters on Thursday.

The province has invested 72.8 million yuan (9.1 million U.S. dollars) to fight the drought. Some 58,000 wells and 8,000 pumping stations were commissioned this summer in the province.

Drought has also affected parts of east China's Anhui Province. "All 42 wells in Tangluo Village have dried up, " said a Huangshan City official.

Drilling by local workers showed that no water could be found 15 meters underground, according to the official, who said that the township government is trying to transport water from neighboring towns.

About 83,000 people are facing a drinking water shortage and 160,000 hectares of cropland have been affected by the drought, according to the provincial flood control and drought relief headquarters.

A worsening drought is also affecting northeast China's Liaoning Province.

From July 1 to August 21, rainfall in the northwestern areas of the province was only 99.9 millimeters, down 61 percent on last year, according to the provincial hydrologic authorities.

The province has so far produced 151 million cubic meters of artificial rainfall, said the provincial flood control and drought relief headquarters.