Use of water quality indices to verify the impact of Córdoba City (Argentina) on Suquía River

We verified the usefulness of water quality indices (WQI) to assess the water quality from multiple measured parameters, and to evaluate spatial and temporal changes. Measured parameters include many of those recommended by the GEMS/Water UNEP program. Two WQI (subjective and objective—WQIsub and WQIobj) take into consideration 20 parameters. Another index (minimal—WQImin) was developed considering only three parameters: turbidity, dissolved oxygen, and either conductivity or dissolved solids. WQIsub tends to overestimate the pollution due to the use of a subjective constant, which is not necessarily correlated with the measured parameters. WQImin shows a similar trend to WQIsub and WQIobj at a lower analytical cost; however, it should be combined with WQIobj to corroborate the results. The use of WQI could be of particular interest for developing countries, because they provide cost-effective water quality assessment as well as the possibility of evaluating trends. As a case study, we report on the use of WQI to evaluate spatial and seasonal changes in the water quality from the Suquía River in Córdoba City (Argentina) and nearby locations. The city urban activity produces a serious and negative effect on the water quality; this is particularly severe in locations following the city sewage discharge. The dry season shows the worst water quality.