Sunday, April 17, 2011
Last Sampling of Location 8, Site #5 (Under 8th Street Bridge During Flood Stage)
These pictures were taken on 4/16/2011, when the creek was at it's highest since this study began. The things of interest are:
1. The effluent in pipes A and B is very slight in the case of A, and no effluent at all from pipe B, in spite of the fact that the rain had just stopped a couple of hours ago. We concluded that the drainage from those pipes was from surface run-off, especially since the environmental bacteria were so high, indicating that the drainage is through surface soil, which has much higher levels of bacteria. There were no coliforms from the effluent from these pipes, when we tested them a few weeks ago, therefore we haven't paid much attention to pipes A and B.
2. We also tested the water from the creek itself once more to see if it still contains somewhat high coliform counts. The photo of the Fmc plate with 0.1ml sample is shown above with only 3 colonies, which to get deciliters would be multiplied by 1000 to give 3000 cfu's coliforms/dl. The low number makes it an estimate, but it is similar to the levels we have gotten before for flood like conditions, apparantly from the high creek levels catching leaky sewage pipes and failed septic tanks out in the country.
We see no reason to test further at Site 8, since we have repeated our testing under different weather conditions and have consistent data on repeats of these different conditions. We have shown that fecal contamination is present in the creek itself, it is higher during high creek levels, and Pipe C apparently picks up fecal contamination, possibly by catching sewage from broken sewer lines, further up the hill from the creek, and empties it into the creek. The impact is not very great though, since coliform levels downstream from the Pipe C are close in number to numbers at oursite #1, which is upstream from all the pipes. .
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