Table 22.  Daily mean dissolved oxygen concentration, Delaware River at Chester, Pennsylvania (station number 01477050), April 1 to November 30, 2002 (U.S. Geological Survey published record) [Concentrations in milligrams per liter;  Max, maximum value; Min, minimum value; --, missing data]
DAY	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV
1	9.5	---	7.3	4.6	5.0	6.4	6.1	8.4
2	9.6	---	7.4	4.7	4.9	6.4	6.0	8.6
3	9.7	---	7.4	4.6	4.9	6.4	5.8	8.8
4	9.7	---	7.4	4.5	4.7	6.3	6.0	8.7
5	9.7	---	7.4	4.5	4.7	6.1	6.1	8.7
6	9.8	---	7.1	4.8	4.9	6.1	6.0	8.7
7	9.8	---	6.9	5.0	5.3	6.1	6.2	8.9
8	9.9	---	6.7	5.2	5.4	6.0	6.3	9.0
9	10.0	---	6.2	5.3	5.5	6.0	6.2	9.0
10	10.1	---	5.8	5.3	5.5	5.8	6.2	8.9
11	9.9	---	5.6	5.4	5.5	5.8	6.5	9.0
12	9.9	---	5.6	5.5	5.4	5.9	6.4	8.9
13	9.6	---	5.5	5.5	5.2	6.1	5.8	8.8
14	9.4	---	5.7	5.3	5.2	6.1	5.7	8.7
15	9.1	---	5.6	5.2	5.3	6.2	5.9	8.7
16	8.9	---	5.5	5.2	5.3	6.2	6.5	8.7
17	8.4	---	5.5	5.3	---	6.1	6.7	9.1
18	8.5	---	5.3	5.4	---	6.2	6.8	9.5
19	8.2	---	5.1	5.2	---	6.0	7.0	9.8
20	7.8	---	4.8	5.0	5.3	6.0	7.4	9.7
21	7.5	7.7	4.5	4.9	5.4	5.9	7.5	9.5
22	7.2	7.7	4.4	5.0	5.4	5.9	7.7	9.5
23	6.9	---	4.6	5.2	5.3	6.0	7.8	9.9
24	6.8	7.6	4.7	5.2	5.3	6.0	7.9	10.2
25	6.5	7.6	4.7	5.5	5.1	6.1	8.0	10.1
26	6.5	7.5	4.6	5.5	5.1	6.3	8.3	10.1
27	6.3	7.4	4.8	5.4	5.0	6.6	8.2	10.1
28	6.2	7.2	4.7	5.1	5.3	6.4	8.0	10.2
29	6.2	7.1	4.5	5.0	5.8	6.3	8.0	10.5
30	6.3	7.1	4.5	5.0	5.7	6.2	8.2	10.6
31		7.1		5.1	5.8		8.3
Mean	8.5	4.7	5.7	5.1	5.3	6.1	6.9	9.3
Max	10.1	7.7	7.4	5.5	5.8	6.6	8.3	10.6
Min	6.2	7.1	4.4	4.5	4.7	5.8	5.7	8.4