The Exhibit - Photos The Water Resources Education Center in Vancouver Washington opened its ABC's of PBT's exhibit in April 2003. Residents Southwest Washington were the first in the nation to have access to a fun and interesting way to learn about Persistent Bioaccumulative Toxic substances (or PBTs) through a brand new interactive exhibit. The PBT exhibit was developed with support from Clark County, the Washington State Departments of Ecology and Health, and Clark Public Utilities. A number of our elected representatives and state officials were on hand together with a host of citizens for the grand opening. You can visit the exhibit anytime, without charge, during regular Center hours.