China's water quality is improving overall but progress is uneven, with some regions finding it hard to meet the annual quality improvement targets, the Ministry of Environmental Protection (MEP) said Monday.

In the first half of the year, the proportion of monitored surface water reaching Grade III or above, which could be used for drinking, rose to 70 percent across the country, up 1.2 percentage points from the same period last year, according to the MEP.

The ratio has surpassed the 68.3-percent target set for 2017.

The proportion of water deemed "inferior to Grade V," the worst in China's water quality grading system and "too polluted for any purpose," stood at 8.8 percent, down 1.7 percentage points from the same period last year.

China has set a target of lowering that to 8.4 percent this year, meaning further efforts are needed to reduce pollution.

Despite the general improvement, eight regions, including Hebei, Jilin and Fujian provinces, reported a drop in the proportion of high-quality water, while five regions, including Heilongjiang and Jiangxi provinces, reported a rise in the proportion of polluted water.

Decades of breakneck growth have left much of China's water seriously contaminated by factory waste and agricultural fertilizers, and the government has stepped up efforts to address the widespread pollution.

In December last year, China began to appoint "river chiefs" with responsibilities including resource protection, pollution prevention and control, and ecological restoration. Their performance will be assessed and they will be held accountable for environmental damage in bodies of water under their supervision.