Cataraqui, Mississippi Valley Issue New Flood Outlook

Both the Cataraqui and Mississippi Valley Conservation Conservation Authorities issued new flood outlooks early this week.

“The region experienced 10 degree C+ temperatures on Saturday, March 7, accompanied by 6 to 20mm of rain. Some localized areas may have seen rainfall amounts of 30mm+.  An additional 23 to 45mm of rainfall is forecast for the period of Tuesday, March 10 to Thursday, March 12. Current forecasts are suggesting the bulk of precipitation will fall as liquid rain, mostly on Wednesday, March 11,” in the

While the forecast for this week in the Mississippi Valley is similar, the spring snow melt is well underway in the Catataqui region and just starting in the Mississippi Valley.

“Snowpack remains in parts of the Mississippi watershed, and continued melting is expected with the forecasted warm temperatures and rainfall. Ground conditions are saturated, which will limit infiltration and increase runoff. Unstable ice conditions may also be present and could lead to the formation of ice jams.

In the Cat system, stream flows and lakes levels are rising from recent rainfall and ongoing snowmelt runoff. Many gauged creeks are seeing high levels with Water Survey of Canada gauged creeks seeing all-time highs for March 9.

While there is a generalised concern about high water levels in the Mississippi system, and concerns about melting ice, there are already specific areas of concern in the Cataraqui watershed, including Frontenac County.

“Runoff from snowmelt and rainfall over the coming days will result in further increases to stream flows and lake levels. Levels could rise quickly, especially if the higher forecasted rainfall amounts materialize. In some locations we could see stream flows and water levels not seen in many years (e.g., 2014 and 2017 high-water periods),” according to the CRCA.

Specific gauged creeks already experiencing all-time high flows for March 09 include:  Wilton Creek, Millhaven Creek, Collins Creek, and Lyn Creek

Additionally, Little Cataraqui Creek West Branch and Buells Creek are much above normal.

“Millhaven Creek flows through the village of Sydenham, immediately downstream of Sydenham Lake Dam is currently about normal but is expected to become elevated in the coming days from snowmelt and rainfall runoff that will raise the water level in the lake and increase discharge downstream.”

Specific locations that could see water levels well above normal seasonal averages include*:  Gananoque River System, Upper Beverley Lake & Delta, Lower Beverley Lake, Gananoque River – the reach between Marble Rock Dam downstream to the 401 causeway (includes Marble Rock Road)

Watch for additional locations added to the above lists in subsequent flood message updates.

The consistently cold temperatures this winter have resulted in thicker ice cover on lakes and streams. Ice cover will weaken and may begin to break up and move leading to possible localized ice jam flooding, especially in areas with a history of ice jamming. There’s also the possibility of shoreline damage (e.g., to docks) from the thick ice, especially where it’s still attached to the shore.

Cataraqui Conservation is urging caution around all dams (inflow and outflow channels) and fast-flowing watercourses. Respect the hazards in these areas by obeying all warning signs, and keep away from booms, buoys and barriers. Stay well back from the water’s edge above and below dams and hydroelectric stations. Creek banks and lake shorelines may be slippery, increasing the chance of falling in.