Here is a link to another article published by Terra Kelly et. al. on lead exposure.
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017656
In this study they found that the California lead ban in the current CA condor range seems to be reducing lead exposure in turkey vultures and golden eagles. They sampled at Big Creek Reserve in 2008 & 2009.