Table 9.
E. coli concentrations (*MPN/100 mL) from beach water collected at time intervals following the triggering of a rain event at Whitefish Dunes State Park beach. There was no significant different between overall E. coli concentrations during a rain event and the seasonal mean E. coli concentrations for this beach using ANOVA (Table 1). Likewise, using Scheffe matrix analysis, there was no significant difference between E. coli concentrations at any sampling times after a rain event and the seasonal E. coli mean. If rainfall was sufficient to trigger multiple rain event notifications on one day, then multiple events were sampled.
| Date of Rain Event | Outfall Pipe 1–3 Hours | 1–4 hours After | 8 hours After | 12 hours After | 24 hours After |
|---|---|---|---|---|---|
| After Rain Event | Rain Event | Rain Event | Rain Event | Rain Event | |
| 5/19/07 | n/a | 2.0 | 1.0 | 2.0 | 2.0 |
| 5/24/07 | n/a | 2.0 | 1.0 | 2.0 | 1.0 |
| 6/2/07 | n/a | 1.0 | 2.0 | 1.0 | 2.0 |
| 6/4/07 | n/a | 4.1 | 4.1 | 4.1 | 49.6 |
| 6/4/07 | n/a | 35.9 | 2.0 | 35.9 | 1.0 |
| 6/7/07 | n/a | 4.1 | 32.7 | 4.1 | 1.0 |
| 6/18/07 | n/a | 45.2 | 37.4 | 45.2 | 3.1 |
| 6/18/07 | n/a | 18.9 | 47.9 | 18.9 | 1.0 |
| 6/18/07 | n/a | 9.8 | 29.2 | 9.8 | 9.8 |
| 7/10/07 | n/a | 9.8 | 21.6 | 9.8 | 1.0 |
| 8/20/07 | n/a | 11.8 | 64.4 | 11.8 | 28.8 |
| 8/29/07 | n/a | 3.1 | 31.3 | 3.1 | 9.8 |
*Most probable number.