I am familiar with the work of Allen Davis at the University of Maryland http://www.ence.umd.edu/%7Eapdavis/Bioret.htm

I have also reviewed the work being done at the University of Connecticut & NC State U.

http://www.canr.uconn.edu/nrme/jordancove/index.htm

http://nemo.uconn.edu/case_studies/index.htm

http://courses.ncsu.edu/classes-a/bae/cont_ed/bioretention/lecture/overview/design_rain.pdf

I am also familiar with the work being done in Prince George's Co. Maryland:

http://www.goprincegeorgescounty.com/Government/AgencyIndex/DER/PPD/lid.asp? h=20&s=40&n=50&n1=160

by the Low Impact Development Center:

http://www.lowimpactdevelopment.org/

And, the Center for Watershed Protection:

http://www.cwp.org/

The journal "Stormwater" is an excellent source of information, but has not (so far as I have seen -- http://www.forester.net/sw.html) addressed bioretention monitoring/research in detail.

Is anyone aware of water quality monitoring and research being done on implemented "bioretention areas" -- created with the specific intent of improving urban stormwater runoff?   I'd appreciate any leads (especially scientific articles) that folks can offer.