Pathway Herbicide applications should be kept at least 50 feet from any water.  Per the product label: This chemical can contaminate surface water through spray drift. Under some conditions, picloram may also have a high potential for runoff into surface water (primarily via dissolution in runoff water). These include poorly draining or wet soils with readily visible slopes toward adjacent surface waters, frequently flooded areas, areas over-laying extremely shallow ground water, areas with in-field canals or ditches that drain to surface water, areas not separated from adjacent surface waters with vegetated filter strips, and areas over-laying tile drainage systems that drain to surface water. An aquatic herbicide such as Aquasweep would be a better option and is labeled for honey locust suppression. It is safe when used as directed on the label.