Most of the mesosaline lakes in the semiarid central Pampas have a high anthropic influence. The objective was to determine the limnological and zooplankton parameters of a mesosaline lake with little human impact, the West Lake of the Parque Luro Reserve, and compare it with previously studied aquatic ecosystems. Monthly samples were taken (2014–2015). The mean depth and salinity were 0.66 m and 29.33 g/L, respectively. The transparency was high and favored the growth of the macrophyte Ruppia cirrhosa. Zooplankton diversity was low, with autochthonous halophilic crustaceans (Daphnia menucoensis and Boeckella poopoensis). Zooplankton density was 20 to 100 times lower than that of other pampean lakes, probably due to the presence of the macrophyte, which distinguishes this lake from others in the region.