Calling out others for their pollution of lakes/waters then admitting that you spray weeds with diesel fuel, especially near a lake, seems like an odd take. In all my training for pesticide application, I've never heard of this method being addressed, so I'm guessing it is not a recommended practice. In any sector (farmers included) there are always those that skirt the "rules" or push the envelope, but untrained pesticide applicating home owners have to bear their fair share of blame for contamination of our water when several of these products are available in many box stores, especially when the untrained adapt a "more is better, quicker attitude". Not only pesticides but fertilizer applications. Some of this has been curbed in the farming sector due to economics (rather than stewardship) but it still has a positive result. Not so much in the residential setting for those wanting that perfect lawn achieved by multiple applications of pesticide/fertilizations throughout the year.
End rant