I just discovered my mother's AL which is on lockdown has admitted another resident. What do you think?

That is against the law put in place by this particular state/Governor. Speak to the Director of Nursing.

For the short term, it is best if everyone considers that we are in a state of emergency.

The main point about this is that everything we all of us do just at the moment falls into one of only two possible categories: Helpful, and Unhelpful. It contributes to getting everyone through this crisis, or it makes it more difficult.

If what you are thinking of doing cannot be made to fit into the Helpful column, please don't do it, at least for now.

So, for example, ringing up the NH - good luck getting hold of anyone in authority at the moment anyway - and demanding information about another resident - yeah, that's going to happen - and how they're going to correct this situation...

Not helpful. Not even helpful in protecting the OP's own mother, come to that - because the new resident is already there, she is a fait accompli.

Sigh. Roll on universal testing, that's what I say. Anyone heard any updates on how long that's going to take?

Perhaps you could move your mom home with you , just temporarily .