Effects of Opened and Closed Spillway Operations of a Large Tropical Hydroelectric Dam on the Water Quality of the Downstream River

Table 5

Water quality parameters of the present study compared with the values before building the Bakun Dam [30].

Parameters	Before building the dam	Values of the present study (closed spillway)	Values of the present study (opened spillway)
pH	6.4	5.6–6.4	6.2–6.5
Temperature (°C)	24.7–25.5	27.0–27.9	26.9–27.8
Dissolved oxygen (mg/L)	8.3–8.5	3.5–6.1	7.6–9.8
Total suspended solids (mg/L)	250–1500	26.0–127.5	25.4–90.2
Ammoniacal-N (mg/L)	0.009	0.12–0.37	0.11–0.49
Nitrate-N (mg/L)	0.047	0–0.04	0.04–0.13