Radioactive contamination originating from the coal fired powered plant and waste dumps located in a bay of the Adriatic which is sensitive to pollution was investigated. Radioactive levels were determined at 2 coal slag and ash piles, one an operating pile and the other an old pile, closed and covered by soil. Both piles are situated close to the seaside and as a result, slag and ash are accumulating in the littoral zone and in the case of the operating pile, are being filled up directly into the sea. Radioactivity measurements were made by gamma spectrometry in the field (in-situ) and in the laboratory. The results showed the presence of natural radionuclides of the uranium and thorium decay series and potassium-40. Absorbed dose rates at the old pile and outside the plant were up to 9 times lower than that determined for the operating pile. The mean value for all the investigated locations around the deposit site was 4 times lower than the mean value at the operating pile. Analysis of seawater samples collected close to the deposit site showed a mean radium-226 specific activity of 51.3 Bq per m3, which is an order of magnitude higher than that found in the Mediterranean sea or the open Adriatic. The mean absorbed dose rate around the plant is not thought to present a significant health risk for the inhabitants. It is recommended that particular attention be given to the sea and sea biota, because they come into direct contact with the deposited material, and could have a serious adverse effect on the marine ecosystem in the future.