Environmental Water Quality Information

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Reservoir Monitoring

Trophic state indices of reservoirs around Taiwan

Legend: No testing data; Oligotrophic; Mesotrophic; Eutrophic

Statistics Time : 2025 Q4

The monitoring frequency of reservoirs is

once every quarter

Rankings of eutrophic reservoirs

26 reservoirs around Taiwan are monitored, 20 of which are important sources of domestic water supply, including Hsin-Shan, Fei-Tsui, Shih-Men, Pao-Shan, Yung-Ho-Shan, Ming-Te, Li-Yu-Tan, Te-Chi, Wu-She, Jih-Yueh-Tan, Lan-Tan, Jen-Yi-Tan, Pai-Ho, Tseng-Wen, Wu-Shan-Tou, Nan-Hua, Ching-Mien, Cheng-Ching-Hu, Feng-Shan, and Mu-Tan Reservoirs. The other six reservoirs, including Hsi-Shih, Pao-Shan II, Ta-Pu, Tou-She, Hushan, and A-Kung-Tien Reservoirs, have smaller storage areas and mainly provide water for industrial or agricultural purposes. Thus, they are considered secondary reservoirs.

1 Feng-Shan Reservoir: 71

2 Shih-Men Reservoir: 56

3 Ming-Te Reservoir: 55

Statistics Time : Nov, 2025

Hsin-Shan Reservoir - Water pollution information

Station:

Legend: No testing data; Oligotrophic; Mesotrophic; Eutrophic

Water monitoring station information

Water Classification

Category A water bodies may be used for Class 1 public water, swimming and as Category B, C, D, and E water bodies.
Category B water bodies may be used for Class 2 public water, Class 1 aquaculture water and as Category C, D, and E water bodies.
Category C water bodies may be used for Class 3 public water, Class 2 aquaculture water, Class 1 industrial water and as Category D and E water bodies.
Category D water bodies may be used for irrigation water, Class 2 industrial water, and environmental conservation.
Category E water bodies may be used for environmental conservation.

Latitude and longitude

25°7'50"，121°42'35.6"

Recent monitoring sample photos

Testing information

Statistics Time : 2025/11/28

CTSI: Mesotrophic46

SD（m）: 1.6

Chl_a（μg/L）: 4.7

Total Phosphate（mg/L）: 0.012

Sampling Depth（m）: 0.5

Atmospheric Temp.（℃）: 20.9

Water Temp.（℃）: 21.1

pH: 7.29

EC（μmho/cm25℃）: 140

DO(Electrode)（mg/L）: 7.7

DOS（%）: 87.1

TB（NTU）: 4.2

SS（mg/L）: 2.0

COD（mg/L）: 4.5

NH3-N（mg/L）: 0.04

TOC（mg/L）: 0.89

TN（mg/L）: 0.86

＊ ND means the test value is smaller than the method detection limit.

More testing items

Hsin-Shan Reservoir I Station - Carlson trophic state index (CTSI) in the last five years

Hsin-Shan Reservoir I Station - Trend chart of Carlson trophic state index (CTSI) in the last five years