## 3 Results and Discussion
### Septic System Density
In the SF3 and CS3 watersheds, all systems were located within either 0.2 or 1 km to the outlet, whereas most systems were located \(>\) 1 km from outlets in the SF1 and CS1 watersheds (Table 1). Therefore, quantifying the septic system density and distance to watershed outlets may be strong indicators of watershed-scale concentrations and exports of FIB. however, this difference was not statistically significant for either bacteria (\(p>0.84\)). This result was expected since only the SF3 watershed contained median values that were greater than the SEW watershed. Differences between the SF3 and SEW watersheds were statistically significant (\(p=0.01\)) for both _E. coli_ and enterococci concentrations, whereas all other watersheds were similar to the SEW watershed. Median monthly exports of _E. coli_ from CS and SF watersheds were lower relative to SEW exports 83% and 75% of the time (Figure 4), respectively. Median monthly exports of enterococci from the SEW watershed exceeded exports from the CS and SF watersheds 75% and 67% of the time, respectively. These differences were not significant for either _E. coli_ (\(p=0.49\)) or enterococci (\(p=0.54\)) yields. The SF3 watershed yielded median FIB that were approximately 1.6 times greater than the SEW watershed. These differences were not significant for either _E. coli_ (\(p=0.49\)) or enterococci (\(p=0.44\)). A study by [PERSON] et al. [15] found that septic watersheds contained substantially elevated FIB concentrations and yields relative to watersheds served by sewers. The current study did not find similar results, but this was likely due to differences in the septic system density. The watersheds in the [PERSON] et al. [15] study contained septic system densities of \(>\)1 system ha\({}^{-1}\). Findings by the current study suggest that the wastewater treatment approach alone may not be a predictor of water quality at the watershed scale, unless watersheds contain elevated septic system densities [12; 14; 15; 16] and limited wildlife and livestock inputs [24]. Thus, significant differences between watersheds using different treatment approaches may be due to other factors that influence water quality (e.g., septic system density, distance of the septic system to the outlet, land use, number of malfunctioning systems/leaking sewer infrastructure, presence and condition of riparian buffers). When considering the broader water quality implications of FIB transport from these watersheds, the data suggest there is cause for concern. The US EPA [5] recommends that recreational waters should not contain geometric mean values that exceed 126 MPN 100 mL\({}^{-1}\) and 35 MPN 100 mL\({}^{-1}\) for _E. coli_ and enterococci, respectively. If recreational water exceeds these values, there is an estimated 36 illnesses per 1000 primary contact recreationists. All watersheds, excluding SF1, exceeded the recommended standard for both _E. coli_ and enterococci regardless of the wastewater treatment approach (Table 2). Furthermore, the US EPA [5] recommends that less than 10% of samples should exceed the statistical threshold value (STV) of 410 MPN 100 mL\({}^{-1}\) and 130 MPN 100 mL\({}^{-1}\) for _E. coli_ and enterococci, respectively. All watersheds exceeded the STV for enterococci concentrations more than 10% of the time. Excluding the SF1 watershed (8%), all watersheds also exceeded the STV for _E. coli_ concentrations more than 10% of the time. These data suggest that watersheds served by septic systems and sewer systems can pose a risk to public health by exposing recreationists to FIB concentrations high enough to indicate fecal contamination, which may be accompanied by pathogenic microbes. Furthermore, FIB concentrations were greater and more variable during warmer months relative to colder months in all watersheds except SF3 (Figure 2), which overlaps with the peak tourism season when water-based recreation is more common. These findings were consistent with previous studies showing greater FIB concentrations during warmer summer months [15; 24; 31; 32; 33].