Category Archives: Credit Valley Conservation

LAKE ONTARIO HAZARD WATCH

A Gale (Wind) Warning is in effect as posted by Environment Canada for Western Lake Ontario Marine Forecast.  Winds east 35 knots (65 km/hr) diminishing to east 25 (45) this eveningthen backing to northeast 25 late overnight. Wind diminishing to north 15 (28) Monday afternoon. Waves 3 metres subsiding to 2 near midnight and to one near noon Monday.

A new DAILY peak for Lake Ontario was set at 75.92 metres above International Great Lakes Datum (m IGLD) on Jun-06-2019. Flood damages in 2017 occurred at a threshold elevation of 75.45 m when waves generated during a storm event overtopped and damaged several shoreline structures.  The local damage threshold elevation does not account for wave generated by winds which can increase flood elevations and cause additional damages; this is especially true with onshore winds associated with storms. The current combination of the storm surge and wave heights could approach or exceed 76 m IGLD. 

Watercourses discharging directly into Lake Ontario may be impacted by backwater from the lake.  Residents and visitors to the Lake Ontario shoreline areas should use extreme caution and obey all closure notices for trails and pathways.  As lake levels increase, certain areas may be cut off or isolated.

CVC will continue to monitor weather and lake conditions.  This Lake Ontario Shoreline Hazard Watch will be in effect until Mon-Dec-02-2019 at 4 pm or updated prior to.  

For more information on this Lake Ontario Hazard Watch, contact CVC during office hours at 905- 670-1615

Flood Outlook Statement

Credit Valley Conservation advises that Environment Canada is forecasting the potential for significant rainfall, starting today through to Friday morning from a low-pressure system approaching from the southwest. Accumulated rainfall amounts of up to 50 millimetres are possible, with the heaviest rain occurring on Thursday afternoon. 

While flooding of the Credit River and its major tributaries is not expected, rainfall associated with this system may result in flooding of low laying and urban areas.

Localized flooding may occur on roadways where leaf litter blocks storm drains. Some watersheds may respond with higher flows and water levels.  As a result, local streams and rivers could become dangerous, especially in the vicinity of culverts, bridges and dams. 

Children should be warned about the dangers and pets kept away from watercourses.  

CVC will continue to closely monitor weather and water levels in the watershed. The Watershed Conditions Statement for Flood Outlook will be in effect through Saturday November 2, 2019, or until further notice. To view current watershed conditions, please visit our real-time monitoring website:  https://cvc.ca/watershed-science/watershed-monitoring/real-time-monitoring/

Watershed Conditions Statement


Credit Valley Conservation is advising that Environment Canada is forecasting a weather system that will bring significant precipitation into the watershed this weekend, beginning Saturday night, into late Sunday morning. Total rainfall accumulation of approximately 30 to 50 millimetres is expected for the duration of this system.

While flooding of the Credit River and its major tributaries is not expected, rainfall associated with this system may result in flooding of small headwater and urban areas. Localized flooding may occur on roadways where leaf litter blocks storm drains. Some watersheds may respond with higher flows and water levels.  As a result, local streams and rivers could become dangerous, especially in the vicinity of culverts, bridges and dams.  Children should be warned of the inherent dangers and pets should be kept away from watercourses. 

CVC will continue to closely monitor weather and water levels in the watershed.  This Watershed Conditions Statement for Flood Outlook will be in effect through to Monday October 28th, 2019, or until further notice. 

To view current watershed conditions, please visit our real-time monitoring website:  https://cvc.ca/watershed-science/watershed-monitoring/real-time-monitoring/

NOTE:     A Flood Outlook Statement is issued as an early notice of the potential for flooding based on weather forecast of heavy rain, snow melt, high wind or other conditions that could lead to high runoff, ice jams, shoreline flooding or erosion.

Note to Public:  CVC’s role during a flooding event is to monitor current watershed conditions and weather forecasts, predict river and creek conditions, and communicate our findings to the public, municipalities and media.  For more information about this message please call CVC between 8:30 and 4:30 (Monday to Friday) at 905-670-1615 and ask for the Flood Duty Officer.  If you are concerned about high water levels in your area, please contact your municipality. For emergencies requiring police, fire or ambulance, call 9-1-1. 

Flood Outlook Statement

The Surface Water Monitoring Center of the Ministry of Natural Resources and Forestry advises that general rainfall of up to 25 mm is forecasted over parts of southcentral Ontario for today and tomorrow with highest amounts forecasted along the western shores of Lake Ontario.  Strong thunderstorms are also forecasted in this region and may bring an additional 25 to 50 mm to localized areas.  The humidex today is expected to reach the high thirties (30s) before dropping down to the mid-teens by early this evening with the passage of a cold front.  These conditions are ideal for the development of severe thunderstorms.

While flooding along the Credit River and its main tributaries are not expected, heavy downpour associated with thunderstorms could result in flooding of urbanized areas. Local streams, rivers, and shorelines could become hazardous, especially in the vicinity of culverts, bridges and dams. People should be warned to stay away from all watercourses, especially children and pets.

CVC will continue to closely monitor weather and water levels in the watershed. The Watershed Conditions Statement for Flood Outlook will be in effect through Wed-Oct-02-2019, or until further notice.

To view current watershed conditions, please visit our real-time monitoring website: https://cvc.ca/watershed-science/watershed-monitoring/real-time-monitoring/

Flood Watch Issued for Lake Ontario Shoreline

The averaged Lake Ontario elevation for yesterday (Toronto, Apr-30-2019) was at 75.41 metres (m) above International Great Lakes Datum (IGLD).  Today, the lake elevation is near 75.46 m.  Flood damages in 2017 occurred at a Lake Ontario elevation of 75.45 m when waves generated during a storm event overtopped and damaged several shoreline structures.  The latest forecast (Apr-30-2019) provided by the Lake Ontario St Lawrence River (LOSLR) Board of the International Join Commission (IJC) is projecting maximum Lake Ontario elevations ranging from 75.65 to 75.95 m for late May to Early June with the upper range being 2 centimetres above the record set in 2017.  The lake damage threshold elevation of 75.45m does not account for wave generated by winds which can increase flood elevations and cause additional damages; this is especially true with onshore winds associated with storms.

Information provided by the Surface Water Monitoring Centre (SWMC) of the Ministry of Natural Resources and Forestry (MNRF) along with the IJC is indicating that rain and snow melt within the Great Lakes and St Lawrence River basin have resulted in high river and lake levels.  Major flooding is currently (Apr/May, 2019) occurring in Eastern Ontario and Quebec due to a combination of high flows in the St Lawrence and Ottawa River. 

The current Lake Erie water elevation is at a new record high for the-end-of-April.  Flows discharging from Lake Erie via the Niagara River, over the Falls, into Lake Ontario are uncontrolled.  Flows discharging out of Lake Ontario into the St Lawrence River are controlled at the Moses-Saunders (MS) Dam.  The MS Dam is operated in accordance to Plan 2014 from IJC which takes into consideration, and balances, the impacts of downstream flooding with higher Lake Ontario levels.  Over next several weeks, Lake Ontario levels will increase and will remain high for the season due to high inflows from Lake Erie and restricted Lake Ontario outflows to mitigate downstream flooding along the St Lawrence and Ottawa Rivers. 

For more information on the Lake-Ontario-St-Lawrence-River-Board and Plan-2014 please visit:

https://ijc.org/en/loslrb

Onshore winds, especially those associated with storms systems, can generate waves resulting in shoreline erosion, flooding and damages.  Wind and wave conditions are provided by Environment Canada via the following website: 

https://weather.gc.ca/marine/region_e.html?mapID=11

Wind gusts at Cawthra Park in south Mississauga are available through the CVC monitoring network: 

Current Lake Ontario level is available from (add 74.2m for IGLD):

https://waterlevels.gc.ca/eng/find/region/6

CVC will continue to monitor weather and lake conditions.  This Flood Watch will be updated by Fri-Jun-14-2019

Watercourses discharging directly into Lake Ontario may be impacted by backwater from the lake.  Residents and visitors to the Lake Ontario shoreline areas should use extreme caution and obey all closure notices for trails and pathways.  As lake levels increase, certain areas may be cut off or isolated.