Table 19. Grade comparison of benthic animal index and water quality by survey site in Yeouicheon

Site	Benthic Macroinvertebrate		Water Quality
	BMI		BOD*		TOC*		TP*
	Value	Grade	Con. (mg/L)	Grade	Con. (mg/L)	Grade	Con. (mg/L)	Grade
Up stream	67.7	B (good)	1.3	Ib (good)	2.0	Ia (very good)	0.038	Ib (good)
Seawon bridge	65.6	B (good)	1.4	Ib (good)	1.8	Ia (very good)	0.034	Ib (good)
Yeoui bridge	60.1	C (usually)	1.5	Ib (good)	1.5	Ia (very good)	0.050	II (slightly good)

Water quality and aquatic ecosystem standards are applied, and DO, SS and pH are all rated Ia (very good).