Icarai beach, located in the municipality of Niteroi, in the metropolitan region of Rio de Janeiro, Brazil, plays an important role in the social context, since it is very popular among the local population. However, it has been suffering negative impacts due to anthropic activities, which are enhanced by increasing urbanization. Ecotoxicological tests using the microcrustaceans Artemia salina as test organism are an important alternative in the evaluation of the toxic state of the water due to their sensitivity to chemical and toxic components of the environment. The present work aimed to evaluate the acute toxicity at two sampling sections (P1 and P2) using low cost methodology, technically simpler and with some adaptations. For this purpose, a number of physico-chemical parameters (temperature, pH, dissolved oxygen, salinity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total coliforms and fecal coliforms) were analyzed, compared to the values established by CONAMA Resolution 357 of 2005, besides the performance of the acute ecotoxicological test with samples of water from the Icaraí beach and with the use of Artemia salina for the evaluation of the lethal dose (LD50). The samples showed a change in toxicity, because in some sample concentrations of the second collection, Section 2 presented a toxic effect. Therefore, the results were satisfactory, since the two ecotoxicological tests presented good answers, associated with their simplicity of execution and economic feasibility.