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| Flood Forecasting and Warning |
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The Central Lake Ontario Conservation Authority maintains a flood forecasting and
warning system. The purpose of the system is to reduce risk to life and damage to
property by providing local agencies and the public with advanced notice, information and
advice so that they can respond to potential flooding and flood emergencies.
Flooding in Ontario is a fairly common occurrence. The most severe flooding on record
in Ontario occurred in October 1954 when Hurricane Hazel passed through the Toronto area.
Hurricanes are not the only type of event that can cause flooding. Heavy spring rains and
snowmelt commonly result in flooding, particularly in larger watersheds. High local
rainfall associated with severe thunderstorms can cause flooding usually associated with
smaller watersheds. Winter ice jams associated with spring break up also has resulted in
severe flooding situations. High great lake levels and/or storm surges can also result in
lakeshore flooding.
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| Winter creek |
Photo: CLOCA |
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| Forecasting |
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The Central Lake Ontario Conservation Authority monitors, on an ongoing basis, weather
forecasts and watershed conditions at locations across the watershed. Water level and
related information is recorded through an extensive network of stream gauges, rain gauges,
snow course sites and staff gauges (monitoring network). These measurements, weather
forecasts and radar information on temperatures and rainfall predictions, along with
historic data, are all taken into consideration when developing a flood forecast.
When spring melt or severe storms are anticipated, the Conservation Authority estimates
the severity, location, and timing of possible flooding, and provides these forecasts to
local agencies.
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| Warning |
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When conditions warrant, CLOCA will communicate with local agencies (municipalities,
emergency services, local media, school boards and government agencies) using one of the
following types of messages.
- HIGH WATER SAFETY BULLETIN is a general notice that potential conditions exist that pose a
risk to personal safety. Flood Safety Bulletins may be posted when streams are flowing at
near bankfull levels, when ice conditions are unsafe, or when stream banks are icy, soft,
and/or slippery.
- FLOOD ADVISORY is a notice of the potential for flooding to occur in the near future
and that measures should be taken to prepare for a possible emergency. Flood Advisories may
be updated depending upon weather and runoff conditions, and will be followed by a notice
of cancellation once the potential for flooding has passed.
- FLOOD WARNING is a notice that flooding is imminent or occurring and that action is
required by municipalities and emergency services. Flood Warnings may be updated depending
upon weather and runoff conditions, and will be followed by a notice of cancellation once
the potential for flooding has passed.
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| Flood Event |
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A flood event may be defined as a sudden increase in watercourse levels resulting from
the occurrence of precipitation, snowmelt, or a combination of the two. The severity of
flood events range from minor increases in creek levels (resulting in “hazardous creek
conditions”), to extreme flood conditions (posing a risk to life and property). These
various types of events, and the corresponding flood response activities, are described in
the Flood Contingency Plan, prepared by the GTA Conservation Authorities for the Regional
Municipality of Durham. A copy of this document is located in the Library section.
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Contact Information
To find out if a flood message has been issued please consult the following:
- Radio, television and daily media will air flood messages.
- Go to the Home page of CLOCA web site.
- Call the CLOCA flood information line at (905) 579-0411 extension 200.
- Contact your local municipality.
If you have an urgent flooding concern, please contact your local municipality. If you
are unable to reach someone, please contact our Flood Duty Officer at (905) 259-4579 and we
will attempt to contact the municipality on your behalf.
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