The Taiwan Water Corp (TWC) yesterday said there is no water quality problem caused by algae at the Shihmen Reservoir’s (石門水庫) water intake point.
The remarks came in response to a report by the Chinese-language Apple Daily yesterday which said that, according to the Environmental Protection Administration’s (EPA) reservoir water quality monitoring data, the water quality at Shihmen Reservoir was in the worst state it had been in the past 11 years.
The report quoted a toxicology expert as saying that it is possible for water purification stations to add chlorine to the water for disinfection and that the increased level of trihalomethane in drinking water may cause bladder cancer.
The EPA’s Environmental Monitoring and Data Processing Bureau Director Chu Yu-chi (朱雨其) said the decrease in water quality is likely to be temporary as it was caused by typhoons that have washed dirt into the water, the report added.
The EPA’s monitoring data showed that the Carlson trophic state index (CTSI) — a commonly used biological indicator of the watershed that measures algal biomass as the basis for trophic state classification — of the water at the Shihmen Reservoir was 62.6 and the CTSI at nine other reservoirs were all above 50, which is considered “eutrophicated.”
In response, the TWC said algae grow mainly on the surface of the water, but it has water intake points at different levels in the water, so while the water level is currently 244.1m, the water intake points for public water supply are at 173.5m and 193.5m, where the water is safe from algae.
It added that according to its monitoring and testing data, the quality of drinking water is within safety limits and the public should not be concerned.