  We present preliminary results of an interferometric study of the water
megamaser in the merger system Arp299. This system is composed of two main
sources: IC694 and NGC3690. There is clear evidence that most of the water
maser emission is associated with the nucleus of the latter, confirming the
presence of an optically obscured AGN as previously suggested by X-ray
observations. Furthermore, emission arises from the inner regions of IC694,
where an OH megamaser is also present. The velocity of the water maser line is
blueshifted w.r.t. the optically determined systemic velocity and is consistent
with that of the OH megamaser line. This finding might then indicate that both
masers are associated with the same (expanding) structure and that, for the
first time, strong 22 GHz water and 1.67 GHz OH maser emission has been found
to coexist.
