Discharges Associated with Domestic Sewage Treatment Lagoons

Domestic Sewage Treatment Lagoon

 

 

The Domestic Sewage Treatment Lagoons General Permit regulates the discharge of treated wastewater from eligible public and private domestic sewage treatment lagoons to state surface waters. The General Permit includes effluent limitations, monitoring requirements, and other conditions. Any eligible facility requesting coverage under this General Permit must submit a complete applicable Notice of Intent (NOI) package; DEQ will review for completeness and issue a written authorization letter that includes requirements specific to that facility.

As part of the 2017 renewal of the Domestic Lagoon General Permit (GP) in 2017, the GP was split into two unique permits: (1) GP for Batch Dischargers and (2) GP for Continuous Dischargers. Specifics for the two permits are found in the tabs below. Alternative, some domestic lagoon facilities may require coverage under an individual permit which is obtained through a separate application process using NPDES Form 2A.

General Eligibility Requirements

To be eligible for authorization under either the batch or continuous General Permit for Domestic Sewage Lagoons, a facility must be: ‚Äč

  • A facultative or aerated sewage treatment lagoon; and
  • Classified as a minor (i.e. have an average daily design flow of less than 1.0 million gallons per day); and
  • Located within the State of Montana, except for within the boundaries of Indian Lands and excluded waterbodies (see below).

Ineligibility Requirements

Even if a facility meets the above eligibility requirements, they are not eligible for coverage under this General Permit if they:

  • Have a pretreatment program (see 40 CFR 403.3);
  • Accept discharge from categorical industrial users (CIU) or significant industrial users (SIU);
  • Operate within the following excluded waterbodies:
    • Outstanding Resource Waters or other waters of unique ecological or recreational significance, based upon considerations of Montana stream classifications, impacts on fishery resources, local conditions at proposed discharge sites, and designations of wilderness areas under 16 USC 1132 or of wild and scenic rivers under 16 USC 1274; or
    • National Parks; or
    • Waterbodies classified as A-1 or A-Closed waters.
  • Are classified as a “new or increased source” that discharges to “high quality water,” as defined in the Nondegradation of Water Quality Subchapter 7.

Furthermore, any facility covered under an individual MPDES permit with site-specific water quality-based effluent limits (i.e. ammonia, nitrate+nitrite, nutrients) cannot request coverage under this GP.

Additional Eligibility Requirements for Batch Dischargers

In addition to the above general eligibility requirements, any facility that wishes to be authorized under the domestic sewage treatment lagoons General Permit for batch dischargers must:

  • Discharge effluent as batch or with a periodic discharge strategy; and
  • Discharge nine months each year or less.

Facilities authorized under the Domestic Sewage Treatment Lagoons – Batch Dischargers are prohibited from discharging during the applicable nutrient criteria period (typically July 1st – September 30th).

 

2013 General Permit

The following information pertains to facilities currently authorized under the 2013 General Permit, which will expire on January 1, 2018. DEQ is no longer accepting NOI packages for authorization under this General Permit.

2017 Batch Discharger General Permit

Domestic Sewage Treatment Lagoons General Permit - Batch Dischargers

General Permit - Batch Dischargers

Fact Sheet - Batch Dischargers

Notice of Intent (NOI) Application Package for Domestic Sewage Treatment Lagoons General Permit - Batch Dischargers

For coverage under the 2017-issued General Permit, permittees must submit a complete renewal application package. A complete renewal application package must include:

A facility's coverage under the 2017-issue GP is effective January 1, 2018, or later, upon receiving an Authorization Letter from DEQ.

2017 Continuous Discharger General Permit

Domestic Sewage Treatment Lagoons General Permit - Continuous Dischargers

Notice of Intent (NOI) Application Package for Domestic Sewage Treatment Lagoons General Permit - Continuous Dischargers

For coverage under the 2017-issued General Permit, permittees must submit a complete renewal NOI package. A complete renewal NOI package must include:

A facility's coverage under the 2017-issued GP is effective January 1, 2018, or later, upon receiving an authorization letter from DEQ.

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