bugs on the WW are a weird thing right now. the flood last august tore stuff up pretty good, and the inverts haven't really bounced back tey. not enough veg for the scuds, etc...
try the south branch if yer set on WW, or north of the park. but get the dnr trout stream map. check out the south branch of the root, and trout run down near pilot mound. much better water right now in my opinion.
Some good books from a tying and fishing flies angle for the Midwest are Ross Mueller's two books. Otherwise, get the DNR Easement booklet and do some exploring. It lists all the streams in southeast MN.
Regards,
D.A.