This study examines the richness of phytoplanktonic species found in one of the aquifers of the Lagunas de Zempoala National Park. The samples were carried out monthly from September 2018 to February 2019. During this period, 26 species integrated in seven divisions, 20 families and seven classes were recognized, among which the Bacillariophyceae class stands out with the greatest diversity (eight species). The species Staurastrum bulbosum was the most frequent throughout the study. In terms of temporal diversity, October presented 15 species and September 13, these variations have to do with changes in abiotic conditions throughout the year. According to previous work, the lake Zempoala can be classified as mesotrophic with periods of eutrophy mainly related to the availability of nutrients and algal blossoming.