Blue Dye in the Weed Treatment?

Some members were wondering why there was no blue dye in the weed treatment anymore. 
Heres the response from PLM:

"As of a few years ago, we can no longer acid wash our boats at our shopsince the wash water drains into a pond that can potentially flow out.  Nowmost of our guys have to wash boats in the field.  That blue dye is a realmess and our guys have found it much easier to not use it since it makes theboats much easier to clean.   The dye has no herbicide effect and is simplya tracer so that we can see where we have been.  We still use it if theapplication requires it but shoreline treatments typically don't.". 

.Bob Richter