2018: Post-Florence Water Test Results are within safe limits

24 September 2018

I took post-Hurricane Florence water samples beginning at 8:22 am on Friday, Sept 21, 2018. The results are within safe limits, and indicate conditions are improving

#1                        Dock                      120  cfu
#2                        Cedar Fork Creek    90  cfu
#3                        Booker Creek          90 cfu

Caution level is individual reading above 400 cfu, or average above 200 cfu. CFU  = colony forming units per 100ml.

Lake water temperature ranged from 79-80F(26.5-27C). The cooler water was in the long “Booker Creek” arm of the lake between North and South Lakeshore Drives. That area was generally free of the floating debris found spread evenly throughout the rest of the lake.  The lake had cooled considerably overnight. I measured the temperature at the SECCI sample site the night before at 90F, and a swimmer in the lake at that time reported the thermocline (layer of cooler water from springs and streams too deep to be warmed by the sun) was about 30 inches, more or less normal depth in all non-drought conditions.

The SECCI clarity reading was 11 inches on the 20th.  The grounds crew was cleaning the park area in the vicinity of the sample site on the morning of the 21st, so I did not attempt to re-sample then.  The entire main bay of the lake and the Cedar Fork in-lake forebay were densely strewn with flotsam (floating debris, consisting mostly of branches, leaves, cut logs, and litter from the ground.  I did an informal “SECCI” test at each sample site using the kayak paddle and the visibility was about 6 inches deep.

The lake level was up 2 inches from normal, and flowing over the entire width of the dam-top spillway (about 100 ft) at about 1.5 inches. This put the lake level about 1-1.5 inches below the wooden retaining wall near the boat racks.  There was debris piling up at the dam, and the Fecal Coliform test results indicate that the ground water coming into the lake from the two main tributary creeks is getting better (bacteriologically) and pushing the slightly more contaminated water through the lake and on downstream.  What we can infer from this is that the bacterial counts are going down (our indicator organism does not live or grow in the water).

Other than being muddy and full of debris, the lake water is within safe limits in terms of bacteria.  The docks were unusually clean, with the resident Great Blue Heron on the far dock on the morning of the test.  The debris was dense enough that I had to take my Dock and Cedar Fork Creek inlet samples in the wake of my kayak in order not to clog the sample bottles.  The Booker Creek inlet arm was mostly free of debris, with the notable exception of an upside down dying catfish.  So the lake water leaves something to be desired in terms of aesthetics. The water is fresh and without any smell, but you will bump into stuff.  Light colored swimwear should probably get washed after you get home from the lake.

We are well away from our 400 CFU caution level. LFA recommends “Swim at your own risk”.  I recommend showering after swimming and rising your canine swimmers off after their swims. The weather forecast is for mild temperatures for the next two weeks.  I will confer with the LFA board regarding whether or not to plan for any additional sampling this fall.

Chuck Henage

09.24.18 by Chuck Henage @ 12:36 pm
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