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EPA shares results of tests on nation's water reservoirs

Two Kaohsiung county reservoirs were named by the Environmental Protection Administration (EPA) yesterday as being the most polluted of the nation's 20 reservoirs.

Feng Shan Reservoir in Kao-hsiung County's Linyuan Township (林園) was the dirtiest reservoir, said Lu Hung-kuang (呂鴻光), chief of the EPA's Department of Water Protection.

"And there is a trend of it getting worse over the years," he said.

The degree of pollution is measured using the Carlson Trophic State Index (CTSI), which assesses the eutrophication of a lake. Eutrophication occurs when nutrient levels in water increase too much, causing excess algal growth.

The enrichment of nutrients in an ecosystem and the cloudiness of the lake resulting from micro-biomass are all measured, Lu said.

Water transparency, total phosphorus levels, and chlorophyll a levels -- which indicate the density of phytoplankton -- also contribute to the index, he said.

CTSI is scaled from 0 to 110, with each 10 units indicating a doubling of algal biomass.

The Feng Shan Reservoir has a CTSI of over 70, the EPA said.

The Cheng Ching Hu Reservoir in Kaohsiung County's Niaosong Township (鳥松) is suffering similar pollution levels.

However the reservoir has seen gradual improvements over the years, with its CTSI dropping from a historic peak of 66 to 50 this June, Lu said.

"But citizens need not worry, since the water still needs to go through a water treatment plant before it runs into the taps at home," he said.

Shihmen Reservoir, Wu She Reservoir, Te Chi Reservoir and the Sun Moon Lake reservoir are among the country's cleanest reservoirs, the EPA said.

Twelve reservoirs received neutral scores, including Feitsui Reservoir, which provides drinking water to Taipei City.

Feitsui's CTSI, last measured in August, was in the low 40s, Lu said.
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