The aquatic environments of the world are facing the severe challenge of eutrophication. Lakes and reservoirs that are regarded as drinking water sources are particularly in danger. Once the water quality deteriorates, serious impacts will occur on the subsequent water supply and drinking water safety. This study focuses on the Aha Reservoir, a sub-deep eutrophic reservoir in Southwest China polluted by phosphorus. This site was selected because it is currently undergoing aquatic restoration. It will be the first to use bubble plume diffusers at the drinking water outlet area where water is removed from the reservoir to provide drinking water to the community, to enhance water quality. There was a significant decrease in total phosphorus (TP) and total nitrogen (TN) concentrations in the experimental zone (0.04-0.02 mg/L and 1.9-1.7 mg/L, respectively), with no significant decrease in TP and TN concentrations at the control sites. Compared with the control sites, concentrations of NH₄⁺, total Fe, and total Mn were reduced by 15.5%, 45.5%, and 48.9%, respectively. In addition, the application of this technique had a significant influence on the evolution of algal phytoplankton in the eutrophic reservoir. The number of cyanobacteria species in the drinking water outlet area decreased by 33-100% during the peak period of algal blooms, with no sign of an increase at all. Moreover, the number of phytoplankton species at the experimental site decreased by as much as 82.6% compared with the corresponding period prior to application. Hypolimnetic oxygenation displayed great effectiveness for aquatic restoration in this eutrophic water system.