## 3 Results and Discussion
### Microbiological Indicators of Water Quality
These values are between the maximum recommended in the legislation (500 MPN/100 mL) and the maximum admissible (10,000 MPN/100 mL) for bathing purposes [17]. There is no specific regulation for agricultural drainage water regarding this parameter, but the proximity of Vieira de Leira Beach about 3 km downstream from the LVID (Figure 1, site 8) justifies this concern. The FC counts (Figure 2 and Table 2) in all samples, except for rice paddies' samples, are above 100 MPN/100 mL. Therefore, irrigation water does not fulfill the quality environmental objectives established [17]. The highest mean values were recorded in the samples at the inlets of the LVID (Figure 1, sampling sites 1 and 2). These high concentrations of FC in the water available for rice irrigation (569 MPN/100 mL) might be explained by sewage contamination, external to the LVID [22]. However, the average FC counts in the water at the outlet of the perimeter (564 MPN/100 mL) are 42% lower than those at the inlet. Sharper drops in FC counts were recorded at the Block II (72%). Considering bathing use, the FC counts of LVID effluent water are above the maximum recommended value (100 MPN/100 mL), but still below the maximum allowable value (2000 MPN/100 mL) [17]. The counts of FC in irrigation are significantly higher than those in samples of soil-water, the root zone, the groundwater (depth of 1 to 2 m) and at the outlet of the level basins (21 MPN/100 mL) (96%). This fact might be explained by the soil effect on the reduction in  
Figure 2: Mean values of counts (and standard deviation) of Total Coliforms (), Fecal Coliforms (), Fecal Enterococci (), expressed in MPN/100 mL, and Fecal Index () at the inlet and outlet of: (**a**) LVID; (**b**) Block II (HB II); (**c**) rice paddies of Block II, including at the soil, soil water and groundwater. this group's values [23]. Our data agree with a study carried out in Brazil demonstrating that paddy agro-ecosystems have the potential ability to circulate the nutrients, thus leading to lower levels of those contaminating microbial agents in the drainage water than in the irrigation water [24]. These results may additionally be explained by the kind of crops grown at the outflow of the LVID (rice and pastures), where the soils are not manured, contrary to the upstream areas of the valley, where other crops are grown. The quality standard established for irrigation water refers to the quality requirements for the reuse of treated urban wastewater in the irrigation of agricultural, forestry and ornamental areas, nurseries, lawns and other green spaces [25]. Regarding microbiological quality requirements, this standard [26] considered the utilization of irrigated crops (e.g., for industry or human or animal consumption) and the adopted irrigation method, which is less restrictive and more flexible than that established in Portuguese legislation [12]. According to [PERSON] and [PERSON] [27], Portuguese legislation [17] is very demanding since the water in most rivers does not have fecal coliforms below 100 MPN/100 mL. The highest average concentrations of FE (Figure 2 and Table 2) were recorded at the inlet of the LVID, with an explanation like that presented for the FC values [22]. The average counts of FE in the water at the outlet and at the inlets of the LVID do not differ significantly and are above the maximum recommended value (100 MPN/100 mL), considering bathing uses of the effluent water from the LVID. A different situation was found between the inlet and outlet of Block II, in which there was an 85% decrease in the FE counts. Significantly higher counts were recorded in the rice field samples (569 MPN/100 mL), either at the inlet to the paddies or in the soil, despite the FE values being significantly reduced in groundwater and drainage (5 MPN/100 mL). The analysis of the Fecal Index, proposed by [PERSON] and co-authors [28], reveals that at the LVID inlets there are signs of human fecal contamination. In contrast, the rice paddy samples indicate a strong influence of the wildlife effect.