<p>There are several water treatments carried out in reservoirs worldwide, and evaluating their effect on water quality is essential for improving techniques. Pampulha reservoir, an urban eutrophic reservoir, is strongly impacted by domestic and industrial sewage. This study aimed to investigate its water quality using a spatial and temporal approach, discussing the effects of existing pollution control techniques in this system, such as Phoslock^®, Enzilimp^®, and waste retaining curtain. Monthly in situ spatial sampling was conducted at 30 points over a year, accompanied by a historical analysis of water quality using secondary data from 2013 to 2021. Results showed that water quality varied historically, with chlorophyll-a, cyanobacteria biovolume, and total phosphorus concentrations exceeding legal limits even after the application of the remediation treatments. Although these specific interventions led to a reduction in cyanobacterial biovolume, they were accompanied by an increase in chlorophyll-a and microcystin concentrations, while total phosphorus levels remained largely unchanged. The region near main tributaries (Ressaca and Sarandi streams) had the poorest water quality indices. The waste retaining curtain was effective in concentrating pollution in this area, leading to worse quality and shallower waters due to sediment accumulation. Thus, spatial variation in water quality was also observed. This study highlights the importance of temporal and spatial scale studies to aid recovery policies and water quality control in urban reservoirs.</p>