## 3 Results and Discussion
### Discussion about Sampling Procedures and Mitigation of Microbiological Risk  
Here, a proposal is presented, based on the knowledge gathered in this study, aiming to optimize the water sampling methodology in the LVID, in terms of time and frequency, to reliably and timely monitor the effects of irrigation water quality and cultivation practices, to allow eventual adaptations throughout the cultivation cycles, and without neglecting the need for further studies. As the sources of pollution outside the LVID are not uniform in time, it is proposed to increase the irrigation water sampling to three periods to assess the water quality in this agroecosystem: (i) One at the beginning of the irrigation season, usually in May, to assess the baseline situation. Information provided allows inferences about the means of water conduction to be adopted during the irrigation season that is about to begin. (ii) A second one at the peak of the irrigation period, in July or the middle of August, which will provide information during the critical period of irrigation, thus allowing adjustment in the conduct of irrigation. From a microbiological point of view,this is the period with higher risk, so these data are required to manage the risk control measures for crops, farmers and consumers. (iii) A third one at the end of the irrigation campaign, after the first autumn rains, usually in September, which allows assessing the impact of the production system, specifically regarding the organic fertilization and the irrigation system on the drainage water into the aquifer.  
For risk mitigation practices undertaken to reduce microbiological contamination in the LVID via the direct contact of the irrigation and drainage water, and the organic fertilizer with the farmer and the consumer (through the edible parts of the plant), adaptions regarding the following may be considered:  
The irrigation method, selected according to the type of crop, for example: (i) preference for drip or furrow irrigation, operated with due care, particularly in the case of vegetables for raw human consumption, to minimize the risk of contamination; (ii) limit the use of sprinkler irrigation to crops undergoing further processing, and consider the nearby crops for consumption in nature, which can be reached by drift, in addition to the farm workers.  
The drainage practices should control the runoff from manured fields, mainly during the rainy seasons, through the soil water retention, promoting its infiltration, and thus reducing the microbial load reaching the surface drainage network. The free access of people and animals to the drainage network should be limited.  
Planning of organic fertilization should be conducted, resorting to a fully composed manure, to minimize the incorporation of pathogenic microorganisms, including those harboring antibiotic resistance genes. Slurry and manure, if spread on the soil surface, should be immediately incorporated.  
Based on the results obtained in this study, it is up to WUA and farmers to adapt the mode of operation and the technologies to minimize the negative impacts of water usage on the conservation of water resource quality. Monitoring water quality within the irrigation district is crucial to know the local reality over time and allow adjustments to be as effective as possible [14, 31, 48, 49], and to inform farmers about special precautions and safety areas where microbiological contamination is at greatest risk [50].