Empirical studies of wave speed for six Australian river reaches show that wave speed at first increases quickly with discharge, then decreases quickly, and finally increases slowly. The increasing parts of the relation can be fitted by power functions with exponents less than unity. Minimum wave speed occurs close to bank‐full discharge. These results have a direct application to storage‐discharge relations and important implications in flood routing and runoff routing. Appendix is available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document 83‐001 ; $2.50. Payment must accompany order.