A biological assessment of water quality in El Placer, Ecuador: The effect of agriculture on stream health and the quality of historical versus current drinking water sources

Although fresh water is one of Ecuador’s most abundant resources, high quality drinking water for its inhabitants is scarce (Wingfield et al., 2021). The most prevalent sources of water pollution in Ecuador are domestic waste, silver and gold mining, oil production, and agricultural chemicals (Buckalew et al., 1997). El Placer, a village located in Tungurahua, Ecuador, is highly dependent on agriculture as a source of income. The first objective of this study was to determine the effect of agriculture on the El Placer’s Tía Anita Stream through comparing the water quality at three sites with varying agricultural influence. The second objective was to investigate the quality of El Placer’s historical and current drinking water sources. These objectives were carried out through comparison of chemical factors, physical factors, hydromorphological quality, and macroinvertebrate composition at each of the study sites. Macroinvertebrate and hydromorphological analyses agree that agriculture did have an effect on water quality in the Tía Anita Stream, suggesting that Site 3 (no agricultural influence) had higher water quality than Sites 1 and 2 (both were influenced by agriculture). Chemical analysis did not agree with these biological findings, but suggested that Site 1 had the lowest water quality, whereas Site 2 had the highest water quality. This inconsistency may have been due to physical factors such as stream velocity causing a higher sediment load in Site 1 (EPA, 1997). Macroinvertebrate, hydromorphological, and chemical analyses agree that Site 4, El Placer’s historical water source, had moderate water quality. It is important to note that, in the past, Site 4’s water quality was likely higher. Macroinvertebrate, hydromorphological, and chemical analyses agree that Site 5, a stream from El Placer’s current potable water source, had very good water quality