A structure for diverting fish away from water intakes comprises a porous dike having a bottom portion, a central portion, and a top portion, the top portion preferably being submerged a short distance below the surface, and the central portion having flow passages. In a preferred embodiment, the top and bottom portions comprise solid blocks and the flow passages in the central portion are lined with zebra mussel resistant sleeves to minimize clogging. Preferably the sleeve can be readily replaced as desired.