Intermittently discharging wastewater systems

The Wastewater Systems Effluent Regulations (the Regulations) apply to your wastewater system if:

The requirements set out below apply to owners and operators of intermittently discharging wastewater systems that are subject to the Regulations. An intermittent system is typically a lagoon with one to four discharge periods a year (hydraulic retention time of 90 days or more).

Identification report

An identification report is required for each regulated wastewater system.

Information required

Change of information

If any information changes, the identification report must be updated within 45 days after the change.

Effluent quality standard

To comply with the Regulations, the effluent must meet specific conditions during discharge:

Pollutant Limit Sample Report Results
Carbonaceous biochemical oxygen demand Average ≤ 25 mg/L Yes* Yes*
Suspended solids Average ≤ 25 mg/L Yes* Yes*
Total residual chlorine  Average ≤ 0.02 mg/L Not required Not required
Unionized ammonia  Maximum < 1.25 mg/L Not required Not required

*Grab or composite sample.

All samples must be tested by an accredited laboratory.  

Acute lethality testing must be done in accordance with:

For more information on acute lethality testing, consult this factsheet

Monitoring reports

Quarterly or annual monitoring reports are required for each wastewater system.

Information required

A statement that indicates that effluent was not deposited during the reporting period.

Alternatively, if effluent was deposited during certain months of the reporting period, a statement must be provided as well as: 

Monitoring, sampling and reporting information for your specific size of wastewater system (refer to the applicable average daily effluent volume)

Average annual daily volume ≤ 2 500 m³ 

Average annual daily volume > 2 500 to ≤ 17 500 m³ 

Average annual daily volume > 17 500 to ≤ 50 000 m³ 

Average annual daily volume > 50 000 m³ 

Combined sewer overflows 

For each deposit day, record:

For each deposit month, record:

Information required in report

For the month of overflow:

Reports due annually, by February 15.

Temporary authorization to deposit un-ionized ammonia 

Owners or operators can apply for a temporary authorization to deposit un-ionized ammonia if it is determined that their wastewater system is depositing acutely lethal effluent due to un-ionized ammonia.

Initial application should be made within 30 days after the determination is made.

Authorization is issued for a three-year period. To extend the authorization, a new application must be made 90 days before the expiry of the existing authorization.

For more information, consult this factsheet

Temporary bypass authorization 

Temporary bypass authorizations can be issued if the owner or operator needs to bypass one or more treatment processes for:

Application should be made at least 45 days before the bypass.

For more information, consult this factsheet

Contact us

If you require further assistance or have any questions, please contact Environment and Climate Change Canada at


This information does not in any way supersede or modify the Wastewater Systems Effluent Regulations or the Fisheries Act, or offer any legal interpretation of those Regulations or Act. Where there are any inconsistencies between this information and the Regulations or Act, the Regulations or Act take precedence, respectively.  A copy of the Wastewater Systems Effluent Regulations is available for your reference.   

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