UPDATE: Conservation authorities watching snow melt throughout midwestern OntarioMarch 14, 2019 5:28am
Local conservation authorities are issuing water safety statements for most of midwestern Ontario.
Minor flooding could be an issue as milder temperatures move into the region.
The Saugeen Valley conservation authority and the Ausable Bayfield Conservation Authorities have released a statement cautioning people of the risk of flooding as thanks to warmer weather and rain expected this afternoon.
Across the Saugeen Valley watershed, the snowpack currently holds a range from 0-90 millimetres of water equivalent. Soils are currently saturated, which means melting snow and any additional precipitation will run off quickly into local waterways. While significant flooding is not expected, watercourses could reach or exceed bank-full conditions, with minor flooding in low-lying areas. There may also be a potential for ice-jam-related flooding on streams and rivers should significant ice break up occur.
The Ausable Bayfield watershed will see most of the remaining snowpack will disappear through the day Thursday ahead of the forecasted rainfall.
Currently, measurable snow cover is limited to the Bayfield and Ausable River headwaters areas of Seaforth, Dublin and Staffa, where approximately 15 millimetres of water equivalent remains in the snowpack.
Major flooding is not anticipated but, with frozen ground conditions, a rapid runoff can be expected. If the high-end rainfall forecasts are observed, levels in watercourses are likely to exceed bank-full conditions, resulting in minor flooding of traditional low-lying flood plain areas. Thunderstorms may result in heavier rainfall amounts and more localized flooding. Levels in smaller watercourses will peak early Friday, March 15, with larger rivers expected to peak later Friday. Flows will remain above seasonal into early next week. The Ausable River will peak in the Port Franks area on Saturday and there will be a risk of an ice jam in the area especially with winds forecast to be about 30 km/h on Saturday.
A water safety note from the Maitland Conservation Authority. The fast, 48-hour thaw is expected to result in a quick melting snowpack which holds 10 to 60 mm of water equivalent. The rapid snow melt, combined with light rain and frozen ground conditions in some areas, means that a fast runoff could happen. According to the MVCA, watercourses will likely reach or surpass bank full levels and ice jamming could cause localized flooding. The combination of slippery banks, broken or unstable ice and fast moving cold water will be dangerous. People are encouraged to stay away from the banks.
The Grey Sauble Conservation Authority has issued a watershed conditions statement that will stay in affect until the weekend. The milder weather and chance of rain has the potential to melt the snow, which has anywhere from 2.5 cm to 15 cm of water content. And with soils saturated already, any new melt will quickly run off to ditches, streams and rivers. Although flows will increase, Grey Sauble believes they will not exceed average spring runoff levels. There is still a concern about potential ice jams. And with the spring runoff, Grey Sauble officials are reminding us that high flows, unsafe banks, melting ice or other factors could be dangerous for recreational users.
-With files from Steve Sabourin