Low Water and Drought

Historically, periods of dry weather and low water levels or drought have been relatively uncommon in Ontario (about every 10-15 years). However, recent studies on changing weather patterns indicate low water levels may become more common, potentially compounded by the province's steadily increasing demands for water.

Low Water/ Drought

Drought is a complex term that has various definitions depending on individual perspectives.  For Ontario Low Water Response drought is defined as weather and low water conditions characterized by one or more of the following:

• below normal precipitation for an extended period of time (3 months or more), potentially combined with high rates of evaporation, can lower lake levels, streamflows and/or baseflows and reduce soil moisture and/or groundwater storage,
• streamflows are at the minimum required to sustain aquatic life while meeting only high priority demands for water; water wells becoming dry; surface water in storage allocated to maintain minimum streamflows, and
• socioeconomic effects occurring on individual properties and extending to larger areas of a watershed or beyond.

As larger areas are affected and as low water and precipitation conditions worsen, the effects usually become more severe.
Droughts cause many severe impacts on the environment and communities including:

• Water shortages for human consumption, industrial, business and agriculture use of for preservation of the environment; 
• Decline of water quality; 
• Increase in wildfires; 
• Increases in insect infestations and plant disease;

Ontario has experienced lower than average precipitation and low water levels since 1998. Great Lake water levels such as Lake Superior have reached the lowest level on record since 1926 during 2007.  During the spring and summer of 1999, southwestern and eastern Ontario experienced an extended period of low rainfall and high temperatures. These weather conditions resulted in some of the lowest surface water levels and driest soils recorded for several decades. In order to ensure the province is prepared for low water conditions in the future, a response plan was developed. This plan, The Ontario Low Water Response , is intended to help co-ordinate and support local response in the event of a drought.

This program utilizes data supplied by the Surface Water Monitoring Centre analyzing streamflow and rainfall information from hydrometric and precipitation gauges across the province.  When conditions fall below the drought indicator levels, the Ontario Low Water Response Plan takes affect.  For additional information regarding the Ontario Low Water Response Indicators, please read the Ontario Low Water Response document.

Find out more about Low Water Conditions.