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We present the results of second epoch ALMA observations of 321 GHz H$_2$Oemission toward two nearby active galactic nuclei, NGC 4945 and the Circinusgalaxy, together with Tidbinbilla 70-m monitoring of their 22 GHz H$_2$Omasers. The two epoch ALMA observations show that the strengths of the 321 GHzemission are variable by a factor of at least a few, confirming a maser origin.In the second epoch, 321 GHz maser emission from NGC 4945 was not detected,while for the Circinus galaxy the flux density significantly increased and thevelocity gradient and dispersion have been measured. With the velocity gradientspanning $\sim$110 km/s, we calculate the disk radius to be $\sim$28 pc,assuming disk rotation around the nucleus. We also estimate the dynamical masswithin the central 28 pc to be 4.3 $\times$ 10$^8$ M$_{\odot}$, which issignificantly larger than the larger scale dynamical mass, suggesting thevelocity gradient does not trace circular motions on that scale. The overalldirection of the velocity gradient and velocity range of the blueshiftedfeatures are largely consistent with those of the 22 GHz maser emission in athin disk with smaller radii of 0.1--0.4 pc and molecular outflows within$\sim$1 pc from the central engine of the galaxy, implying that the 321 GHzmasers could trace part of the circumnuclear disk or the nuclear outflows.

Second Epoch ALMA Observations of 321 GHz Water Maser Emission in NGC 4945 and the Circinus Galaxy