state of their research into the problem of coal tar sealant pollution. Well-illustrated graphics, like the one above, helped communicate the science of coal tar to the Congressional representatives.
The Pavement Coating Technology Council (PCTC) countered that they didn't have a chance to present their perspective on science with their own scientists.
Brian Van Wye from the District of Columbia stated that the District appreciates the USGS work and their ban represents "low hanging fruit" when dealing with polycyclic aromatic hydocarbon (PAH) pollution in their waterways. Fish in D.C. area streams commonly have fish tumors associated with PAH toxicity.
A Water Environment Federation representative asked about the mobility of PAH's downstream of a parking lot. While they are highly mobile with sediment, Dr. Barbara Mahler of the USGS notices that "PAH hotspots" can be present near parking lots.
Another question was about testing for the effectiveness of a ban in places like Austin, Texas. Unlike the approach taken by PCTC in testing highly variable stream sediment, the USGS believes the appropriate location for determining trends would be larger water bodies like lakes and after at least 10 years.
An audio recording of this talk is available.