Canada
About this guideline ▾
Canada has three sets of federal water quality guidelines:
the Canadian Council of Ministers of the Environment (CCME) Canadian Water Quality Guidelines,
Health Canada's Guidelines for Canadian Recreational Water Quality, and
Environment and Climate Change Canada's Federal Environmental Quality Guidelines (FEQGs).
We use these on the Water Rangers platform to help interpret monitoring data.
Oxygen
Freshwater
| Range | Level | Impact |
|---|---|---|
| ≥ 6.5 mg/L | Met guideline | Essential level for aquatic life |
| ≤ 6.4 mg/L | Exceeds chronic guideline | Too low to support most aquatic life |
When an observation has multiple samples, the highest single value is compared against this standard. Any sample above the threshold flags the observation.
Dissolved oxygen is the most fundamental parameter for aquatic life, entering water through the atmosphere and photosynthesis, but reduced by excess nutrients from sewage, agricultural runoff, and industrial waste. When levels drop too low, fish and invertebrates experience reduced growth, reproductive failure, and death, with eggs and young organisms especially vulnerable. The CCME sets the long-term freshwater guideline at 9.5 mg/L for cold-water early life stages and 6.5 mg/L for other life stages, with most Canadian waters defaulting to cold-water guidelines where the temperature regime is unknown.
https://ccme.ca/en/chemical/154