Sometimes, the graininess induced by high ISO (and inclement weather) is not that bad. In fact, for IR rendered as black-and-white, it can add to the overall image impact.
Taken with the AFS 24mm f/1.4 Nikkor and the B+w 093 IR filter on the PrimaLuce Z5, this scene reminds *me* eerily of the ancient psychothriller film "Pond of the Dead" which to my generation of Norwegians at least is very familiar. Fog hung almost to the ground and everything everywhere was dripping wet.
I would set the range of ISO for which noise is very acceptable to 100-1600, with possible excursions to 3200 ISO or even higher. Thus a camera not as ISO-compliant as the Z6/Z6.2, but more than sufficiently capable for most requirements.
Among Norwegian nature photographers, the ever-present occurrence of power lines along any inland water body is an insider joke. You can probably see the presence here is as expected, too. One tends not to see this issue during the actual shoot, but surely expects to see the "law" in action later on during image processing.
