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tokens: al. 2002 ). In their consideration of the maser data on the turbulence in the flows from the massive YSOs, Strelnitski et al. ( 2002 ) proposed that “the maser hot spots originate at the sites of ultimate dissipation of highly supersonic turbulence.” This assertion finds support in a well-ordered spatio-kinematical pattern in the small-scale water maser features reported in Cepheus A HW2 by Uscanga et al. ( 2003 ), in W75N by Uscanga et al. ( 2005 ), and in W49N by Gwinn ( 1994b ). Observations of Uscanga et al. ( 2005 ) suggested microstructure with a size about 1 au. This structure had a short lifetime supposedly on the order of a month. All information on the known examples of the structures with an “eddy-like” spatio-kinematical pattern does not contain evolutionary information and has a form of snapshots, although the other maser structures in Cepheus A HW2 show persistence on the timescales of years (Torrelles et al. 2001 ). Uscanga et al. ( 2005 ) speculated that these short-lived kinds of spatio-kinematical microstructures are either produced by fluid instabilities within the shocked material or correspond to nearly round cloudlets (turbulent eddies?) in the ambient medium. In the sections below, we discuss a spectroscopic origin for our observations as well as three dynamical phenomena that may explain them. 4.1. Spectroscopic Origin: Hyperfine Splitting The velocity separation of 0.54 km s −1 between the components in Figure 6 is close to the velocity separations of the H 2 O hyperfine splittings of 0.45 km s −1 between the F = 7–6 and F = 6–5 transitions and 0.58 km s −1 between F = 6–5 and F = 5–4. However, there are several problems with this spectroscopic hypothesis. First, the components of the double-peaked spectrum in Figure 6 are not spatially coincident, so they would have to be associated with different hyperfine components. Second, the F = 7–6 hyperfine transition has the lowest frequency (and F = 5–4 the highest) of the three strong transitions (Kukolich 1969 ), while the strength order is F = 7–6, F = 6–5, then F = 5–4 (Deguchi Watson 1986 ). We would therefore expect the strongest peak at the lowest frequency (most positive Doppler shift) in our spectrum, but the opposite is seen in Figure 6 . Moreover, all three of the hyperfine transitions introduced above have comparable line strengths (see Figure 1 of Deguchi Watson 1986 ), so a triplet spectrum would be expected rather than a doublet in the case of hyperfine intensity anomalies. We think this explanation is unlikely because it would require some complicated combination of hyperfine-specific pumping and/or competitive gain effects to generate the observed spectrum. 4.2. Keplerian Rotation For the first dynamical interpretation, the maser hot spots (see Figure 9 ) might be amplifying along chords (i.e., filaments) in the plane of a Keplerian disk, orbiting a protostellar or protoplanetary object, viewed approximately edge-on. In this case, the length of the filaments