Fly ash and bottom ash are being used extensively for stabilization of roads. Unpaved county roads in rural areas are often being resurfaced with bottom ash to improve their stability. A preliminary, uncontrolled examination was conducted to assess the environmental problems that may result from the use of fly ash and bottom ash on highways. To do this, soil, plant and run–off water samples were collected from county roads and highways in Oklahoma that were constructed using either of the two ash forms. These samples were analyzed for fourteen elements of which eight are under the USEPA regulation list of priority pollutants for solid waste and drinking water. The results indicated that the allowable limits for six out of the eight elements were exceeded in the run-off water samples. Compared with the control, fly ash, bottom ash, coal and soil-core samples all contained significantly higher levels of all elements; however, except for barium all were below the regulatory levels. The concentrations of As, Sb, Pb, Ni, Se, and TI in the run-off water samples are high enough to be of concern, although they are below the allowable limits for drinking water. These six elements are found at much higher levels in the fly ash and bottom ash than in the input coal. More Ba is released into the run–off water when the roads were under heavy traffic. Although there was no visual damage observed on the collected plant samples, much higher than normal levels of most metals, were obtained in the tissues.