No. of sites in BOD5 concentration classes	BOD5 <=1.4 [mg O2/l]	BOD5 1.4-2.0 [mg O2/l]	BOD5 2.0-3.0 [mg O2/l]	BOD5 3.0-4.0 [mg O2/l]	BOD5 > 4 [mg O2/l]	<=1.4	1.4-2.0	2.0-3.0	3.0-4.0	> 4
Prut (7)	1	1	5	0	0	14	14	71	0	0
Dnister (19)	1	1	14	3	0	5	5	74	16	0
Desna (6)	0	5	0	1	0	0	83	0	17	0
Tisa (8)	0	0	6	2	1	0	0	67	22	11
Sievercki Donets (16)	0	0	2	14	0	0	0	13	88	0
Dnipro (54)	6	5	24	13	6	11	9	44	24	11
Pivdennii But (20)	1	2	1	2	14	5	10	5	10	70
Total (131)	9	14	52	35	21	7	11	40	27	16