Flood Watch

The Essex Region Conservation Authority Advises that, due to record high lake levels, a Flood Watch is in effect for all shoreline areas within the Essex Region, including Pelee Island. Areas of potential concern are the low lying beach communities and shoreline areas along Lake St. Clair, the Detroit River, and Lake Erie, as well as low lying areas along the downstream reaches of major tributaries. Unless superseded by a Flood Warning, this Flood Watch will remain in effect until further notice. Conditions will be continuously monitored and re-evaluated with weekly updates based on short and long-range weather forecasts. However, it should be noted that water levels are not anticipated to peak until June-July 2020. Therefore, our office is advising residents to take proper caution especially near shoreline areas where conditions can change quickly based on wind speed and direction.

Areas of Potential Concern:
With record high lake levels, areas that may be potentially impacted can vary from day-to-day based on wind speed and direction. Areas at risk of flooding and significant nearshore erosion as it relates to wind are described below. The direction stated is the direction the wind blowing from.

Northeast/East Winds
– Lake St. Clair shoreline from Windsor to Belle River;
– Lake Erie shoreline including Pelee Island;
– Detroit River shoreline.

North Winds
– Lake St. Clair shoreline

Northwest Winds
– Lake St. Clair shoreline from Belle River to Tilbury North

South/Southwest/Southeast Winds
– Lake Erie Shoreline including south Pelee Island

West Winds
– West shoreline of Pelee Island

Weekly weather outlook:
Current available information shows that wind speeds are expected shift to overnight to a west wind and increase in speed up to 30 km/hr for a brief period of time on Wednesday. By Thursday April 9th, winds are forecasted to increase to speeds between 30 and 40 km/hour sustained out of the west, shifting northwest and lasting through Friday April 10th. Rain accumulation into early Wednesday morning is expected to be around 10 mm; however, there is the potential for severe weather over that same time period that could generate an additional 10-25 mm in localized areas with strong, variable winds. Should we approach the upper end of potential excess convective precipitation overnight tonight within a 12 hour period, drains and watercourses would be expected to have a rapid increase in water level.

Current Conditions:
Preliminary estimates for March 2020 water levels for both Lake St. Clair and Lake Erie were confirmed. Lake St. Clair and Lake Erie monthly averages finished roughly 27 cm and 29 cm above their respective monthly averages for March 2019. The levels are 3 cm and 7 cm higher than previous monthly average records set in 1986. These values are coordinated monthly averages based on daily levels obtained from gauges in both the United States and Canada and more accurately reflect static water level conditions as opposed to daily levels which are highly influenced by wind, waves, and atmospheric pressure.

In addition to the new records for the month of March, both lakes also set new records for starting elevations for the month of April. Lake St. Clair’s beginning-of-April level was 17 cm above the previous record set in 1986. Lake Erie also broke its beginning-of-April water level set in 1986 by 12 cm. As a matter of perspective, these levels are roughly 34 cm and 33 cm (respectively) above the starting levels in April 2019.

In general, these elevated lake levels bring an elevated risk of flooding and nearshore erosion across the watershed. Measurable wind from any direction can potentially cause minor flooding issues while sustained wind speeds nearing 30 km/hr can and has caused significant flooding, substantial nearshore erosion, and damage to shoreline structures.

Elevated lake levels continue to cause downstream reaches of major tributaries to remain elevated. With tributaries full of lake water, it reduces their capacity to handle rainfall and has the potential to cause local rivers, creeks and streams to spill into low-lying areas. As we approach spring, low-pressure systems can bring both rainfall and strong winds that can both impact local watercourses and produce unpredictable waves and water level changes impacting shoreline communities.

Great Lakes Water Level Outlook:
Current available predictions as of March 27th indicate that lake levels are expected to rise anywhere between 7 cm and 13 cm from now until late April. This of course was before the recent rainfall events that caused a spike in water level on Lake St. Clair. Long-term predictions indicate that monthly average peak water levels could be 8 cm higher than levels experienced in June and July of 2019 for both lakes. This would leave both lakes, the Detroit River, and river-lake interface zones at an elevated risk of flooding. Lake St. Clair is of particular concern should those forecasted levels be realized as it would mean Lake St. Clair would have a static water level (no wind setup) less than 30 cm below the modeled 1:100 year peak instantaneous water level (which includes wind setup). ERCA will continue to monitor levels and forecasts and advise accordingly.

Monitoring:
The Municipality of Leamington should continue to monitor the flood control dykes in the Southeast Leamington Area, including the Mersea Road 1 Dyke and the Marentette Dyke.

The City of Windsor should continue to monitor water levels along the flood control dykes within the Little River Drain corridor.

The Township of Pelee should continue to monitor areas along the shoreline that have experienced significant erosion, such as the West Shore Road and McCormick Road.

Essex Region Conservation Authority officials will continue to monitor conditions and advise accordingly.

Caution:
People should take extra caution to avoid areas where flooding is occurring as well as rivers, streams, and shoreline areas during significant rainfall and wind/lake events. The combination of slippery banks, waves, waves overtopping shoreline structures, and fast moving water can be dangerous. Standing water can also present its own unseen hazards. Children, pets, and livestock should be kept away from flowing or standing water as well as shoreline areas.

James Bryant, P.Eng.
Water Resources Engineer, Watershed Management Services
519-819-7912
Tim Byrne, C.E.T.
Director, Watershed Management Services
519-796-2300
April 7, 2020
5:30 pm
April 14, 2020 6:00 pm
Upon receipt, hand directly to the Flood Coordinator or Emergency Planner for your Municipality or Agency.
Upon receipt, hand directly to your newsroom.
Watershed Conditions –
Safety Bulletins:
High flows, unsafe banks, melting ice or other factors that could be dangerous for recreational users such as anglers, canoeists, hikers, children, pets, etc. Flooding is not expected.
Watershed Conditions –
Flood Outlook:
Early notice of the potential for flooding based on weather forecasts calling for heavy rain, snow melt, high wind or other conditions that could lead to high runoff, cause ice jams, lakeshore flooding or erosion.
Flood Watch Bulletins:
Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services and individual landowners in flood-prone areas should prepare.
Flood Warning Bulletins:
Flooding is imminent or already occurring in specific watercourses or municipalities.