The Waters Rising - Sheri Tepper - questions

[Montero]

Picked up The Waters Rising by Sheri Tepper from the library the other day. Looking on Fantastic Fiction I see it is book 2 of The Plague of Angels. Looking at the very brief description of the plots they seem completely different.
So my questions are
Can the Waters Rising be read as a standalone?
Will it spoil the previous book A Plague of Angels to read the Waters Rising first?
(Just trying to pick a book to read on my Saturday off - ie tomorrow.)

And final question - is it one of her more upbeat ones (by the end) or one of her grim ones?
Not really in the mood for grim at the moment.

 

[Montero]

In the end I picked a book off my shelves to re-read, put The Waters Rising to one side for later. If anyone can answer the question about whether it is best to read the previous book first that would be appreciated - I could order it from the library and then read both.