As part of the Stratford-Avon River Environmental Management Project, the River Systems Unit of the Ontario Ministry of the Environment carried out surveys during the summers of 1980 and 1981 to collect data on the physical characteristics of the Avon River. Data from these surveys are to be used in the development of a mathematical model to predict water quality changes under different management scenarios. Standard methods for measuring channel geometry, time of travel and streamflow were used. Results indicate that riffle-to-pool distance varied from 325 m to 550 m, average depth between reaches was consistent, ranging from 0.17m to 0.35m, and average width varied from 11.82 m to 20.31 m. Streamflow was observed to range from 0.04 m3/sec to 63.7 m3/sec at Station 10 during the period 1965-1979. Time of travel ranged from 4 to 10 hours depending on the reach, with total time of travel for the river downstream of Stratford varying from 26 hrs to 74 hrs, depending on flow. Reductions in flow observed between two downstream stations were attributed to anomalies in the operation of the Stratford WPCP. Substrate type was homogeneous throughout the river below Stratford although aquatic plant communities varied from reach to reach.