A field experiment to study frazil ice blockage of water intake trash racks in hydropower plants is described. The experiment, conducted during the 1990/1991 winter using a submerged video camera, was designed to investigate ice accumulation on trash racks and compare this with laboratory tests. Differences between ice accumulation and adhesion on steel bars with and without a rubber coating were examined. The submerged video camera functioned well and was found to be an excellent tool to document and evaluate these ice phenomena. Frazil ice problems occured in air temperatures as high as -4°C. Frazil ice accumulation started on the upper section of the trash racks and progressed downwards. Ice was mainly deposited on the upstream face of the racks. The rubber coating material, with its poor adhesion to ice, appeared to mitigate frazil ice problems in the intakes in two ways. Ice was much more easily removed from trash rack elements coated with rubber and frazil did not stick to coated trash racks under small depress of supercoolings.