No Sampling Error Here
December 26, 2007 | 08:44 PM

Aloha to Tony the Process Wastewater Guy. Mahalo for taking the time to comment on the article about bacterial sampling at Honokowai Channel.

You raise several important things to be considered in water quality sampling. I want to assure readers that these factors were considered in our studies. We used procedures approved by USEPA for water testing at 40 CFR Part 131. We did quality control including field blanks to discern if the bacteria were coming from the water we were sampling or from sampling technique or contaminated containers.

One of our biggest challenges was getting the samples to a qualified (i.e. certified)lab on another island within the six hour holding time, but we did it as documented by chain of custody records.

The study documented not only the bacterial standards violations mentioned in the article, but also exceedances of standards for nutrients. Both Honokowai Stream and coastal receiving waters are on the Clean Water Act 303(d) list of impaired waters. This means that the state Department of Health has reported to Congress that the water quality does not support the uses of the waters (i.e.fishable, swimmable uses)

Details of the findings include:

The results obtained document numerous exceedances of applicable state water quality criteria concentrations in both the Honokowai Channel and near shore coastal waters in the vicinity of the channel mouth. The enterococcus criteria for recreational use was exceeded both in Honokowai Channel and in the coastal waters at the channel mouth based on the geometric mean of five samples collected over a 25-30 day period. There were nine exceedances of the enterococcus criteria concentration based upon individual sample results (six in the channel, three in near shore waters). Additional bacterial indicator organisms were added to the analyte list to discern whether elevated Enterococcus results were attributable to human sewage sources or could be due to soil sources of Enterococcus. The results of the October 18, 2006 sampling event indicate elevated levels of Enterococcus, Clostridium perfringens, and Fecal coliform
bacteria, as well as the presence of E. coli. The geometric mean of sample concentrations for nitrite-nitrate nitrogen, total nitrogen, total phosphorus, chlorophyll a, and turbidity exceeded the allowable criteria concentration geomean for both the channel and the near shore waters. Chlorophyll-a in seawater exceeded the marine criteria. There is no inland water criteria for chlorophyll-a, however high concentrations are present in the Honokowai Channel. The geometric mean of TSS in channel samples exceeded the allowable criteria concentration geomean.

Robin - the water quality wahine