The production behaviors of odorant 2-methylisoborneol (MIB) in water bodies by Planktothrix sp. have not been understood very well. Through four-year investigation in Miyun Reservoir, a huge mesotrophic drinking water reservoir for Beijing known to have the MIB episodes, we found that the Planktothrix sp. bloomed with MIB in this reservoir together during September and October. The spatial distribution of MIB was investigated with a large sample size to trace the main living areas of the deep living MIB-producing cyanobacteria. The results indicated that the north shallow region is the major habitat for Planktothrix sp. due to the relatively high concentrations of nutrients. Quantile regression analysis between Planktothrix biomass and MIB concentration shows that the risk of MIB exceeding the odor threshold (15 ng L-1) in water was as high as 90 % when the Planktothrix density was more than 5.0 × 105 cells L-1, while the risk was reduced to 10 % when the Planktothrix density was below 1.6 × 104 cells L-1. This study will allow better understanding of the environmental behaviors of Planktothrix sp., and can provide useful information for better management of drinking water lakes/reservoirs experiencing the T&O problems caused by deep living cyanobacteria species.