Many years ago, I sent two 1000 gal spray rigs to a golf course to spray trees for gypsy moths. One of the trucks tipped over on a dirt access road and spilled 800 gals into a drainage ditch that supplied water to a pond on the course. Fortunately, the applicator followed my instructions not to add pesticide until they were onsite in the maintenance yard. Only clean water was spilled. Whew, we dodged a big one.