Proposal for a methodology to develop pesticide monitoring plans for drainage from water supply systems

Abstract

The growing use of pesticides in agricultural activities raises concerns about the presence of these compounds in water sources. The water treatment processes used in most cities have limited ability to remove pesticides. This means that, when detected in water sources, they will possibly be present in treated water distribution systems. One of the instruments used to assess contamination and promote public policies aimed at preserving public health is the monitoring of water quality. However, representative monitoring of pesticides is a challenge. Several uncertainties contribute to this problem. The presence of pesticides in water is influenced by several factors, such as the dependence of precipitation, soil moisture conditions, chemical characteristics of compounds, and the degree of anthropization of the watershed. Given the issues addressed, this article proposes a methodology to increase the representativeness of pesticide samples collected in water supply systems for human consumption. The methodology employs multicriteria analysis to select a set of municipalities whose drinking water intakes will be monitored according to a staggered monthly distribution, over the two semesters of the year. In this way, it is possible to obtain 12 samples per parameter in this period. Based on assessments of initial results, recommendations are made to prioritize pesticides that should remain in the following year's monitoring program, as well as collection frequencies. In addition to optimizing costs, these annual assessments allow policy makers to establish the best actions to minimize the presence of pesticides in water distributed for human consumption.