Wastewater permit limits and monitoring practice questions
20 free practice questions from 40 CFR Part 122 Subpart C. Each answer is explained and linked to the rule it comes from.
Wastewater permit limits and monitoring
20 questions across 7 topics. After each answer you see why it is right, with a link to the official source.
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Additional conditions for specified permit categories
1. Under 122.42(b), who must give the Director adequate notice of any new introduction of pollutants from an indirect discharger that would be subject to section 301 or 306 of the CWA if it were discharging directly?
- A. The indirect discharger alone
- B. All POTWs
- C. The EPA Regional Administrator
- D. The State water quality standards agency
Show answer
Answer: B. All POTWs
"All POTWs must provide adequate notice to the Director of the following: (1) Any new introduction of pollutants into the POTW from an indirect discharger which would be subject to section 301 or 306 of CWA if it were directly discharging those pollutants"
2. What does 122.42(b)(3) say adequate notice from a POTW shall include?
- A. The name of each industrial user's certified operator
- B. A copy of each indirect discharger's production records
- C. Results of a whole effluent toxicity test on the POTW's sludge
- D. Information on the quality and quantity of effluent introduced into the POTW, and any anticipated impact of the change on the quantity or quality of effluent discharged from the POTW
Show answer
Answer: D. Information on the quality and quantity of effluent introduced into the POTW, and any anticipated impact of the change on the quantity or quality of effluent discharged from the POTW
Adequate notice "shall include information on (i) the quality and quantity of effluent introduced into the POTW, and (ii) any anticipated impact of the change on the quantity or quality of effluent to be discharged from the POTW."
3. Under 122.42(a)(1), an existing manufacturing discharger must notify the Director of a routine or frequent discharge of a toxic pollutant not limited in its permit if the discharge will exceed which of the listed notification levels?
- A. The highest of the listed notification levels
- B. The lowest of the listed notification levels
- C. The average of all the listed notification levels
- D. Whichever listed level the discharger selects in its application
Show answer
Answer: A. The highest of the listed notification levels
The duty applies "if that discharge will exceed the highest of the following" notification levels.
Establishing permit conditions and limitations
4. Under 122.43(c), what must a permit give when a permit condition is incorporated by reference?
- A. A full copy of the regulation attached as an appendix
- B. A summary written by the permittee
- C. A specific citation to the applicable regulations or requirements
- D. The date the regulation was first proposed
Show answer
Answer: C. A specific citation to the applicable regulations or requirements
"All permit conditions shall be incorporated either expressly or by reference. If incorporated by reference, a specific citation to the applicable regulations or requirements must be given in the permit."
Source: eCFR: 40 CFR 122.43, Establishing permit conditions (as of Nov 4, 2026)
5. What does 122.44(a)(2)(ii) say about how long a monitoring waiver for a guideline-listed pollutant is good?
- A. It is good for 10 years regardless of the permit term
- B. It is good indefinitely once granted
- C. It is good only for the term of the permit and is not available during the term of the first permit issued to a discharger
- D. It is available only during the term of the first permit issued to a discharger
Show answer
Answer: C. It is good only for the term of the permit and is not available during the term of the first permit issued to a discharger
"This waiver is good only for the term of the permit and is not available during the term of the first permit issued to a discharger."
6. Under 122.44(g), which pollutants must the permit's list of pollutants subject to 24-hour reporting include?
- A. Any toxic pollutant or hazardous substance, or any pollutant specifically identified as the method to control a toxic pollutant or hazardous substance
- B. Only conventional pollutants such as BOD and TSS
- C. Only pollutants that have no limit in the permit
- D. Only pH and temperature
Show answer
Answer: A. Any toxic pollutant or hazardous substance, or any pollutant specifically identified as the method to control a toxic pollutant or hazardous substance
"This list shall include any toxic pollutant or hazardous substance, or any pollutant specifically identified as the method to control a toxic pollutant or hazardous substance."
Monitoring and reporting requirements
7. 122.44(i)(1)(iv)(A) gives two ways a method can be sufficiently sensitive. Which of these is one of them?
- A. The method was published most recently
- B. The method is the least costly approved method
- C. The method minimum level (ML) is at least twice the effluent limit
- D. The method minimum level (ML) is at or below the level of the effluent limit established in the permit for the measured pollutant
Show answer
Answer: D. The method minimum level (ML) is at or below the level of the effluent limit established in the permit for the measured pollutant
A method is sufficiently sensitive when "The method minimum level (ML) is at or below the level of the effluent limit established in the permit for the measured pollutant or pollutant parameter" or when "The method has the lowest ML of the analytical methods approved under 40 CFR part 136" or required under subchapter N or O.
8. Except as provided in paragraphs (i)(4) and (5), what reporting frequency for monitoring results does 122.44(i)(2) set?
- A. Monthly for every permittee
- B. Case by case, dependent on the nature and effect of the discharge, but in no case less than once a year
- C. Quarterly for POTWs and annually for all others
- D. Once per permit term
Show answer
Answer: B. Case by case, dependent on the nature and effect of the discharge, but in no case less than once a year
Reporting requirements "shall be established on a case-by-case basis with a frequency dependent on the nature and effect of the discharge, but in no case less than once a year."
9. Under 122.48(b), the required monitoring that all permits specify, including type, intervals, and frequency, must be sufficient to yield what?
- A. Data which are representative of the monitored activity, including continuous monitoring when appropriate
- B. Data from the single day of highest flow each year
- C. Data collected only during daylight hours
- D. Data averaged over the full permit term
Show answer
Answer: A. Data which are representative of the monitored activity, including continuous monitoring when appropriate
Permits specify "Required monitoring including type, intervals, and frequency sufficient to yield data which are representative of the monitored activity including, when appropriate, continuous monitoring".
10. Under 122.44(i)(1)(iv)(B), how is monitoring conducted for a pollutant that has no approved method under 40 CFR part 136 and no method otherwise required under subchapter N or O?
- A. Monitoring is not required for that pollutant
- B. The permittee chooses any laboratory method it prefers
- C. Monitoring waits until EPA approves a method
- D. According to a test procedure specified in the permit
Show answer
Answer: D. According to a test procedure specified in the permit
In that case, "monitoring shall be conducted according to a test procedure specified in the permit for such pollutants or pollutant parameters."
POTW pretreatment, BMPs and reissued permits
11. Under 122.44(j)(2)(ii), when must a POTW provide a written technical evaluation of the need to revise local limits under 40 CFR 403.5(c)(1)?
- A. Only when an industrial user asks for one
- B. Following permit issuance or reissuance
- C. With every discharge monitoring report
- D. Only after a pass-through violation
Show answer
Answer: B. Following permit issuance or reissuance
POTWs must "Provide a written technical evaluation of the need to revise local limits under 40 CFR 403.5(c)(1), following permit issuance or reissuance."
12. Under 122.44(l)(1), except as provided in (l)(2) and absent materially and substantially changed circumstances, when a permit is renewed or reissued its interim effluent limitations must be at least as stringent as what?
- A. The limits in the permittee's original application
- B. The average effluent quality achieved during the last year
- C. The final effluent limitations, standards, or conditions in the previous permit
- D. The interim limits that applied in the first year of the previous permit
Show answer
Answer: C. The final effluent limitations, standards, or conditions in the previous permit
When a permit is renewed or reissued, "interim effluent limitations, standards or conditions must be at least as stringent as the final effluent limitations, standards, or conditions in the previous permit".
Calculating permit conditions
13. Under 122.45(d)(2), how are limitations for a POTW's continuous discharges stated, unless impracticable?
- A. As instantaneous maximum and annual average limitations
- B. As daily minimum and quarterly average limitations
- C. As a single annual average limitation
- D. As average weekly and average monthly discharge limitations
Show answer
Answer: D. As average weekly and average monthly discharge limitations
For continuous discharges, limitations "shall unless impracticable be stated as" "Average weekly and average monthly discharge limitations for POTWs." Dischargers other than POTWs get maximum daily and average monthly limitations.
Source: eCFR: 40 CFR 122.45, Calculating NPDES permit conditions (as of Nov 4, 2026)
14. Under 122.45(b)(1), what are a POTW's permit effluent limitations, standards, or prohibitions calculated on?
- A. Design flow
- B. A reasonable measure of actual production
- C. Peak hourly flow on the day of sampling
- D. The flow reported in the most recent DMR
Show answer
Answer: A. Design flow
"In the case of POTWs, permit effluent limitations, standards, or prohibitions shall be calculated based on design flow."
Source: eCFR: 40 CFR 122.45, Calculating NPDES permit conditions (as of Nov 4, 2026)
15. Under 122.45(c), unless one of its listed exceptions applies, in what terms must permit limitations for a metal be expressed?
- A. The metal's concentration in the sewage sludge
- B. Total recoverable metal as defined in 40 CFR part 136
- C. Pounds of metal per ton of production
- D. The metal's concentration in the receiving stream
Show answer
Answer: B. Total recoverable metal as defined in 40 CFR part 136
Limitations for a metal "shall be expressed in terms of “total recoverable metal” as defined in 40 CFR part 136 unless" one of the exceptions in (c)(1)–(3) applies.
Source: eCFR: 40 CFR 122.45, Calculating NPDES permit conditions (as of Nov 4, 2026)
16. 122.45(f)(1) requires limits to be expressed in terms of mass except in listed cases. Which of these is named in the exception in 122.45(f)(1)(i)?
- A. Biochemical oxygen demand
- B. Zinc
- C. Temperature
- D. Ammonia
Show answer
Answer: C. Temperature
Mass limits are required "except: (i) For pH, temperature, radiation, or other pollutants which cannot appropriately be expressed by mass".
Source: eCFR: 40 CFR 122.45, Calculating NPDES permit conditions (as of Nov 4, 2026)
Permit duration and schedules of compliance
17. What does 122.46(c) allow the Director to do about a permit's term?
- A. Issue any permit for a duration that is less than the full allowable term
- B. Issue any permit for up to 10 years
- C. Extend any permit indefinitely by letter
- D. Let the permittee choose the permit's term
Show answer
Answer: A. Issue any permit for a duration that is less than the full allowable term
"The Director may issue any permit for a duration that is less than the full allowable term under this section."
Source: eCFR: 40 CFR 122.46, Duration of permits (as of Nov 4, 2026)
18. What time for compliance does 122.47(a)(1) set for any schedule of compliance under 122.47?
- A. A date chosen by the permittee, as long as it falls within the permit term
- B. Compliance only after the permit is next reissued
- C. Compliance within 14 days following each interim date
- D. Compliance as soon as possible, but not later than the applicable statutory deadline under the CWA
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Answer: D. Compliance as soon as possible, but not later than the applicable statutory deadline under the CWA
"Any schedules of compliance under this section shall require compliance as soon as possible, but not later than the applicable statutory deadline under the CWA."
Source: eCFR: 40 CFR 122.47, Schedules of compliance (as of Nov 4, 2026)
19. Except as provided in 122.47(b)(1)(ii), what must a schedule of compliance that exceeds 1 year from the date of permit issuance set forth?
- A. Only the final compliance date
- B. A bond to cover the cost of the work
- C. Interim requirements and the dates for their achievement
- D. A plan to stop discharging
Show answer
Answer: C. Interim requirements and the dates for their achievement
If the schedule "exceeds 1 year from the date of permit issuance, the schedule shall set forth interim requirements and the dates for their achievement."
Source: eCFR: 40 CFR 122.47, Schedules of compliance (as of Nov 4, 2026)
Federal laws and disposal into wells, POTWs or land
20. Under 122.50(a), when part of a discharger's process wastewater is disposed into a well, into a POTW, or by land application instead of to waters of the United States, how are the permit's effluent standards and limitations adjusted?
- A. They are doubled to account for the other disposal
- B. To reflect the reduced raw waste resulting from such disposal
- C. They are dropped from the permit entirely
- D. They stay unchanged in every case
Show answer
Answer: B. To reflect the reduced raw waste resulting from such disposal
Applicable effluent standards and limitations "shall be adjusted to reflect the reduced raw waste resulting from such disposal."