The Washtenaw County (Ann Arbor, Michigan and area) siren net started at 11:30 a.m. Saturday 2020-03-07 Eastern time, and was done by about 12:15 p.m. Of the two dozen or so sirens monitored, three were in need of maintenance.
The county emergency operations center runs a net on N8DUY on 145.15 with a negative offset and a 600 Hz PL. This repeater covers the whole area. The emergency warning sirens are tested monthly and used in emergencies like tornado warnings.
I joke that this is the "fix your radio hour", but really there is no better way to be sure that all your equipment is in working order than to be part of a net. I discovered that the stock Radioddity RD-601 antenna on my RD-5R radio didn't work all that well, but when I swapped it out for a Nagoya NA-771 that was already on my other Baofeng UV-5R rigs, it fit perfectly and worked much better.
Bonus: listening to sirens up close! They are rather loud.