The GRCA has dozens of automatic water level gauges on rivers and streams at important locations throughout the Grand River watershed.
The information from the gauges is relayed to the GRCA head office and used to update the charts shown in this section of the website. They are updated every hour, usually around the half-hour.
These gauges are an important part of our flood forecasting and warning systems. They give GRCA flood managers real-time information on changes in flows so they can issue flood messages to municipal flood co-ordinators and the public.
The gauges have automatic alarms that are triggered by a sudden change in water levels. A heavy, localized rainstorm or an ice jam might trigger an alarm.
The flows charts are also useful to recreational river users such as anglers, canoers and others.
A number of factors influence the accuracy of the charts including:
For more information read our Provisional Data page.