20 Fecal Coliform Bacteria
The presence of fecal coliform bacteria in surface water indicates fecal contamination from warm-blooded animals, which is linked to disease-causing viruses and bacteria (Glass, 1999). Sources include waste from septic systems, domestic animals, waterfowl, and other wildlife (Glass, 1999).
ADEC fecal coliform standards have two components: a 30-day geometric mean limit and a single-sample limit (the threshold that no more than 10% of samples in a 30-day period may exceed). This monitoring program collects two discrete samples per year — one in spring and one in summer — not a series of samples over a 30-day window. As a result, the geometric mean criterion cannot be evaluated and is not reported here. The applicable comparison for this dataset is the single-sample limit: 400 CFU/100 mL for secondary recreation use and 40 CFU/100 mL for drinking water use (ADEC, 2002). A single observation above these limits should not be interpreted as a definitive standard violation, but does warrant consideration of additional, more frequent monitoring to evaluate whether the 30-day geometric mean criterion would be exceeded under closer scrutiny.
The data summary below is from the 2016 Kenai River Baseline Water Quality Assessment and reflects data collected through 2014.
The highest level of fecal coliform recorded was 2980 CFU/100ml at Mile 6.5 during the summer 2002, however this sample may be unreliable because the duplicate sample was below the MDL of 1 CFU/100ml. The next highest recorded concentration in the mainstem was 580 CFU/100ml at Mile 6.5 during the summer of 2003, and the lowest levels were 0 CFU/100ml at several locations (Table 26). The highest median in the mainstem occurred at Mile 6.5 in the spring and at Mile 1.5 in the summer. The other medians along the mainstem were all below 10 CFU/100ml for the summer and the spring. The concentration of fecal coliform was generally higher in the summer than in the spring in the mainstem and the tributaries (Figures X - X).
In the tributaries, the concentration of fecal coliform ranged from a high of 520 CFU/100ml in Soldotna Creek during spring 2001 to 0 CFU/100ml at multiple sites (Table 52). During the spring, Beaver Creek had the highest median, and during the summer, No Name Creek had the highest median. In the summer, the median concentrations were relatively high in Slikok Creek and Beaver Creek, in addition to No Name Creek. Juneau Creek, Russian River, Killey River, and Moose River all had relatively low medians during the spring and the summer. In the summer, the tributaries had higher median concentrations of fecal coliform than the mainstem, but in the spring, the levels in the tributaries and the mainstem were more similar. (Figures X - X)
| Standard Type | Value | Unit | Regulatory Authority |
|---|---|---|---|
| Recreation (single-sample limit) | 400 | CFU/100 mL | ADEC |
| Drinking water (single-sample limit) | 40 | CFU/100 mL | ADEC |