The Maitland Valley and Grey Sauble Conservation Authorities have issued Watershed Conditions Statements in response to the stretch of mild temperatures is expected over the next few days followed by a period of widespread rain this weekend.
With temperaturs reaching the mid to high teens, the unseasonably warm temperatures will eliminate what is remaining of the snowpack throughout the Maitland and Nine Mile River watersheds.
Grey Sauble is reporting snow cover water content of up to 12.5 cm. Although the majority of the watersheds are between 5 cm and 7.5 cm.
Snowpack water equivalents were measured earlier this week and showed a wide range across the watershed. Open fields were generally bare, with potential sources of runoff limited to Tuesday’s snowfall and frozen ponded areas. The woodlots still hold a much more significant amount, with snow water equivalent measurements ranging from 30-60 mm. In addition to this expected snowmelt, 10-20 mm of rain is currently forecast for overnight Friday and Saturday.
The rate of runoff and impacts on stream flows will vary depending on the localized snowmelt and rainfall totals. River levels will likely be elevated for a prolonged period, possibly approaching or slightly exceeding bank-full conditions in some areas. Significant flooding is not expected at this time.
As the snow begins to melt, soils become saturated under the snow and additional snow melt will quickly run off into ditches, streams and rivers. Flows will increase and may reach average/normal spring runoff levels later this week. Although unusual flooding is not expected at this time, seasonal flooding of low-lying areas will likely occur. Grey Sauble is also concerned about the potential for ice jams as there is still some ice cover throughout their watersheds. The increase in water levels will likely mobilize the ice sheets and they may cause jamming and localized flooding.
Residents are reminded to use caution near all watercourses as streambanks can be slippery and the water is extremely cold and fast-flowing.
Conservation staff will be closely monitoring the situation over the next few days, paying close attention to the track of the incoming low-pressure system and associated rainfall totals.