Temporal changes to the ice regime of a regulated cold-regions river

The Peace River, the major tributary to the Slave River in northern Canada, has been regulated since 1968 by the W.A.C. Bennett Dam, over 1200 km upstream from the Peace-Slave River confluence. This paper illustrates how now regulation has influenced the timing and duration of solid ice cover formation on these rivers. Increased water temperature, as a result of hypolimnetic water releases from the reservoir, totally precludes the formation of an ice cover immediately downstream of the dam. Data from sites along the Peace River indicate that the ice regime upstream of the town of Peace River has been altered significantly, with only intermittent ice covers forming. At the town of Peace River ice cover formation has been delayed by more than one month The timing and duration of the main ice season on the lower reaches of the Peace River and on the Slave River have not changed significantly since regulation.