Looking for a Alaska Legal Forms And Templates? Download it for free!

DRAFT Final Report ACWA-08-05

8 October 2008

Discussion

Fecal coliform bacteria results showed no pattern with relation to the three suspected sources: the

village of Koliganek, the Mulchatna River, and the village of New Stuyahok. The study design for this

project allowed for comparison of fecal coliform concentrations between both upriver and across

channel control sites and the site just below the suspected input at the affected bank. At each of the

three sites, fecal coliform bacteria concentrations were more abundant at the upriver and cross channel

control sites than the affected bank site on at least three of the five collection dates (Figure 4). At the

Koliganek site, the mean (from the five sampling events) at the affected bank downstream from the

village (LNR-1a) was 17.6 fc/100ml, which was lower than the means from the upstream and across

channel sampling locations at the Koliganek site (Table 2). The affected bank below the Mulchatna

River site (LNR-2a) had a mean of 23.0 fc/100ml, compared to a mean of 22.8 fc/100ml at its upstream

control sites and a mean of 22.0 fc/100ml at its across channel control sites. The affected bank site

below New Stuyahok had a mean of 22.1 fc/100ml, compared to a mean of 22.5 fc/100ml at the

upstream control sites and 20.2 fc/100ml at the across channel control sites. Sites that were located

downstream from the affected bank sites showed similar patterns, with no significant differences

between upstream and downstream sites. A complete list of the fecal coliform data can be found in

Table A2.

When viewing the fecal coliform data in relation to river gage data, the August and September 2007

sampling events occurred when river stage was relatively low (Figure 3). The river stage during the

October 2007 and May and June 2008 sampling events was considerably higher. River stage was

similarly high in both the October 2007 sampling event, when fecal coliform concentrations were at

their lowest, and the May 2008 sampling event when fecal coliform concentrations were at their highest

(on average, almost eight times higher).

Downstream sites were set up across channel to attempt to understand the downriver fate of bacteria.

Since elevated fecal coliform levels were not detected at the three potential sources, an analysis of the

downstream fate of the bacteria is unwarranted. When viewed with the other fecal coliform data, no

meaningful trends emerge.

The data did not suggest that the three possible sources of fecal coliform identified in previous studies

were contributing to the overall fecal coliform bacteria load in the river. Other potential sources of fecal

coliform include wildlife, recreationists, and sport fishers and hunters. During the May 2008 sampling

event when fecal coliform levels were at their highest, dozens of moose and waterfowl were seen by the

sampling crew along the river. During the October 2007 sampling event, when fecal coliform levels were

at their lowest, the sampling crew spotted no wildlife along the river (Appendix B). The May 2008 spike

in fecal coliform concentrations was accompanied by a spike in turbidity (Table A1) and a three-fold

drop in specific conductance (Table A4), suggesting that overland flow during spring break up may have

been contributing to these spikes.

Page 11

Draft Final Report Acwa-08-05 - Continuation Of Lower Nushagak River Fecal Coliform And Water Quality Assessment - Alaska Department Of Environmental Conservation - 2008 Page 11