perigee tide issues

Last year in Sepatember there was a perigee tide that i had not seen previously and the predicted tide hieght was greater than 9.3 feet.
We had samples beaches just as the tide was ebbing and found high bacteria counts.
Now this was something that i had expected with other high tides, but not found in much significants and so this was the first and only perigee tide that i had found what was suspected.
There were no duplications of the tide or of the results.
The high tide this year occured past midnight and sampling was done at incoming tide after the low.
There was nothing, no bacteria.
The situation remains unproven, but it also begs the question on how long such an effect might last?
The rainfall issue (washing bacteria into the Sound) was carefully studied and we discovered that 24 hours was always enough, but 12 hours was not enough.
This tide will not be repeated anytime soon (at least till after 2013 is over) and i will not be the one to find the issues and the particulars.