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DRAFT Final Report ACWA-08-05

8 October 2008

Our rationale for this design is that human waste and pollutants are likely be greatest near the stream

bank at the three sites where elevated levels of fecal coliform have been detected in the past, and

diluted toward the midpoint of the stream. In addition, by collecting fecal coliform samples both above

and below the main sample site, we would be able to determine a more precise location of the source of

the bacteria and gain some understanding of its downstream fate.

Assumptions for this design include:



The main flow/midpoint of the stream is the most representative of the stream channel.



Fecal coliform bacteria concentrations will be greatest nearest the affected bank.



The first two sampling events in the fall 2007 will occur during peak use periods by hunting camps

on the river, while the third fall sampling event will occur after the hunting peak. The spring 2008

sampling events will coincide with peak fishing guide camp activity.

After lab samples were collected, they were immediately put on gel ice and delivered to the laboratory

the following morning to meet the 30 hours holding time. The only mishap that we encountered during

our fecal coliform sampling was the loss of a sample bottle cap during our May 2008 sampling trip,

which resulted in only two DI blanks being sent to the lab for that sampling trip.

Sampling methods

The YSI 556 multi-meter and turbidimeter were calibrated the night before each of the sampling trips

while in Ekwok. All measurements and sample water were collected from the upstream side of the boat

at elbow depth. Water temperature, dissolved oxygen, pH, specific conductance, and barometric

pressure readings were taken with the YSI 556 multi-meter. Turbidity tubes were filled at elbow depth

and analyzed with the Hach 2100 turbidimeter. All field measurements were made in at least duplicate

with 10% distilled water blanks for turbidity measurements. The YSI multi-meter probes and turbidity

tubes were rinsed thoroughly with distilled water after each use and with sample water before

recording measurements/collecting samples. Digital photographs were taken.

Laboratory sample bottles were filled at elbow depth below the water surface. The sampler collected

the sample by submerging the inverted sample jar into the water while facing upriver. Once the bottle

reached elbow depth, the sampler turned the bottle opening into the current and upright, allowing it to

fill, before pulling it from the water and capping. Samples were immediately labeled and collection

times were logged. Samples were placed on gel ice and remained there until delivered to the lab on the

following morning.

The same measurements and samples were collected at an upstream transect, located upriver from the

main site transect, above all suspected human bacteria influences in the immediate area. The same

measurements and samples were collected at a downstream transect, located approximately 300

meters downstream from the main site transect.

Measurements and analysis techniques

Field measurements and laboratory analysis followed ADEC-approved methods to insure data quality

and to provide continuity with previous studies. Additional details about sampling procedures and

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Draft Final Report Acwa-08-05 - Continuation Of Lower Nushagak River Fecal Coliform And Water Quality Assessment - Alaska Department Of Environmental Conservation - 2008 Page 7