Left panel: a figure taken from Zhang et al. (2023), of which white circles and orange squares represent the H₂O maser spots detected in W51-North from our VLA observation and from Imai et al. (2002). The meaning of the colors in the background is the same as that in the upper panel of Figure 5. Middle panel: white circles represent the H₂O maser spots detected in W51e2-E from our VLA observation, and the meaning of colors in the background is the same as that in Figure 7. Right panel: white circles filling in gray represent the H₂O maser spots detected in W51e8 from our VLA observation, and their size indicates the flux intensity of the H2O maser spots. Since the flux intensities in W51e8 are much lower than that of other sources, they are amplified about 100 times for clear comparison. The meaning of the colors in the background is the same as that in Figure 7. Notably, the source “W51e4” is beyond the range of this subfigure, although we pointed out the relative direction of the location of this source to the “W51e8” subregion.