Over 80 percent of rivers and nearly 70 percent of lakes around the country were found to be in good shape in terms of water purity last year. The Ministry of Environment said on Tuesday that 85.1 percent or 97 out of a total 114 rivers made the cutoff for the government's water quality standard in 2010. The goal was achieved five years ahead of a 2015 deadline.
A river is considered clean when its biochemical oxygen demand measures below three mg/l. The test for BOD is a chemical procedure which finds the level of pollution by determining the amount of dissolved oxygen consumed by organisms living in the water to break down organic material.
For lakes the purity is assessed through a chemical oxygen demand test, with a COD level of under four mg/l considered clean. Out of 49 lakes examined last year, 61.2 percent or 30 passed the test, far less than the government's goal of 93.9 percent by 2015.
Experts say that state-led quality control efforts and heavy rainfall last year contributed to the vast improvements in rivers, but that the standards are much more stringent for lakes which are often polluted from livestock fields or agricultural land.
Meanwhile, all tested bodies of water met 15 standards for health safety, including levels of heavy metals and toxic materials.