Periurban lakes are important ecosystems in the maintenance of Amazonian communities. However, they suffer from anthropic impacts aggravated by their proximity to urban centers. With that in mind, our research aimed to evaluate the environmental quality in five periurban lakes (Maicá, Mapiri, Juá, Verde and Piranhas) in Santarém, in the Brazilian Amazon, using the mollusk fauna (environmental indicators) associated with abiotic water variables. Manual collections and measurements of abiotic variables were carried out considering the least rainy season in the region. Eight families, 16 genera and 19 species were identified, with the highest abundance of Pomacea lineata (n=133) and the exotic species Corbicula fluminea (n=333). Lakes Mapiri and Maicá showed higher values of temperature, turbidity and electrical conductivity, in addition to low values of dissolved oxygen. These lakes also showed greater species richness and abundance, but with a prevalence of species known for their preference for eutrophic environments. In addition, the presence of the exotic species Corbicula fluminea only occurred for Lakes Mapiri and Maicá. Thus, the results point to the poor environmental quality of the Mapiri and Maicá lakes and, although the Juá, Verde and Piranhas lakes did not present an expressive number of mollusc species, their abiotic variables suggest better environmental quality