The annual occurrence of extreme water levels associated with the spring break-up period is one of the most significant hydrologic events in Northern Canadian rivers and has important morphological, ecological and socio-economic implications. Numerous rivers experience their annual peak water level due to in-channel ice processes which frequently exceed those observed under open conditions. To this end, the physical controls contributing to river ice processes and maximum, spring break-up water levels have only been examined as case studies and have not been quantified in a large-scale assessment. Previous assessments of hydro-climatic controls on river ice have largely focused on ice phenologies rather than exploring the effects of hydro-climatic controls on maximum water levels under ice conditions. This paper evaluates the dominant physical and hydro-climatic factors that control the magnitude of ice-induced and open channel water levels of rivers across Canada, including a variety of hydro-climatic regions ranging from warm maritime to arctic continental. A return period assessment for 136 Water Survey of Canada hydrometric stations from 1913-2006 and the classification of rivers into ice-dominated and open water dominated regimes was performed. A multivariate analysis was used to classify the ice and open water regimes according to a number of physical variables such as mean river gradient, basin elevation and basin size. Hydro-climatic variables including accumulated degree-days below freezing and the 0˚C isotherm were used to correlate regime types to the dominant hydro-climatic region. This approach is the first quantitative assessment of the dominant physical and hydro-climatic controls on peak magnitude events in ice and open water dominated rivers.