This research examines the methods of controlling the surface evaporation rate of water reservoirs in drought conditions. Using physical and chemical coatings is one of the new methods to prevent evaporation. In this research, the combination of octadecanol and hexadecanol, as well as hexadecanol dissolved in ethanol, has been used as a chemical method to control evaporation on the surface of three ponds designed with dimensions of 2 × 2 × 2 square meters in the hydrometeorological research station of the Faculty of Natural Resources of Lorestan University. Quantitative (evaporation rate reduction) and qualitative (possible changes in some chemical and microbial parameters) effects were investigated in a 3-month period from 7/23/2021 to 10/22/2021. The monolayer combination of octadecanol and hexadecanol showed the highest reduction in evaporation rate (23%) with a significant difference of 5% compared to the control group. Hexadecanol monolayer ranked second with 17% reduction in evaporation. The chemical parameters of alkalinity (pH), total dissolved solids (TDS) and the presence of microbial biomass (turbidity) were investigated. The acidification of the environment due to the release of CO2 in the treatment ponds led to a decrease in pH. The faster growth of algae, bacteria and solid particles has increased the turbidity in the control pond compared to the treatments.