During the Fall and Winter, the Haliburton and Kawartha Lakes are lowered by increasing their outflows. This drawdown prepares the lakes for the spring snowmelt and reduces the threat of high water and ice damage. Snow course sites throughout the Trent and Severn drainage areas are surveyed regularly beginning in January. Information about the depth and water content of the snowpack obtained from these surveys aids in forecasting the total volume and peak runoff for the upcoming spring freshet. Spring March, April and May are critical months for Waterway hydrologists as melting snow and rain fill waterway lakes.
Attention focuses on the weather.
Both heavy rainfall and prolonged warm temperatures will cause rivers and lakes to peak. The historical record shows this often happens more than once during spring freshet. Efforts to control this flooding are hampered by narrow channels, insufficient storage capacities in some lakes and the differing abilities of soils throughout the drainage basins to absorb water. While flood abatement is a primary spring-time concern of waterway staff, care is also taken to ensure that water flows and levels are adequate to protect fish spawning beds. During the summer, attention shifts to managing water levels and flows.