NPDES Stormwater Sampling and
Monitoring Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
Download Pdf
1.Under the National Pollutant Discharge Elimination System (NPDES) Multi-
Sector General Permit (MSGP), the primary purpose of stormwater sampling
is to:
A. Determine the value of industrial property.
B. Assess employee performance during storm events.
C. Evaluate whether stormwater discharges are being adequately controlled
and comply with permit requirements.
D. Measure groundwater recharge rates.
Answer: C
Rationale: Stormwater sampling under the NPDES program is intended to
evaluate the effectiveness of stormwater control measures, identify
potential pollutant sources, and determine compliance with permit
requirements.
2. Which of the following best describes a "measurable storm event" for
routine NPDES stormwater monitoring?
A. Any rainfall regardless of duration or amount.
B. A storm event meeting permit-defined criteria, often separated from
,previous measurable events by at least 72 hours.
C. Only storms producing more than 5 inches of rainfall.
D. Snowfall events only.
Answer: B
Rationale: Most NPDES permits define measurable storm events using
minimum precipitation thresholds and antecedent dry periods, commonly
requiring at least 72 hours between qualifying events.
3. Grab samples collected for stormwater monitoring should generally be
obtained:
A. At the end of the calendar month.
B. During the first flush or within the permit-specified timeframe after
discharge begins.
C. Only after laboratory approval.
D. After stormwater has infiltrated.
Answer: B
Rationale: The first flush often contains the highest pollutant
concentrations, making early sample collection essential for representative
monitoring.
4. Which parameter is commonly monitored because it indicates the
amount of suspended particulate matter in stormwater?
A. pH
B. Dissolved Oxygen
C. Total Suspended Solids (TSS)
D. Chloride
Answer: C
Rationale: TSS measures suspended particles that can transport pollutants,
reduce water clarity, and impact aquatic habitats.
, 5. The primary purpose of maintaining a chain-of-custody form is to:
A. Record employee attendance.
B. Document sample handling from collection through laboratory receipt.
C. Calculate rainfall intensity.
D. Measure stream flow.
Answer: B
Rationale: Chain-of-custody documentation preserves sample integrity by
recording every individual who handled the sample until laboratory
analysis.
6. Which instrument is commonly used to measure stormwater pH in the
field?
A. Radiation detector.
B. pH meter.
C. Spectrophotometer only.
D. Soil auger.
Answer: B
Rationale: Portable calibrated pH meters are widely used for field
measurement of stormwater acidity or alkalinity.
7. Why is equipment calibration important before stormwater sampling?
A. It increases rainfall.
B. It ensures measurement accuracy and defensible monitoring results.
C. It reduces permit fees.
D. It eliminates laboratory analysis.
Answer: B
Rationale: Calibration ensures instruments provide accurate
measurements that meet regulatory and quality assurance requirements.
, 8. Which stormwater pollutant is commonly associated with vehicle
maintenance areas?
A. Nutrients only.
B. Petroleum hydrocarbons.
C. Salt exclusively.
D. Pollen.
Answer: B
Rationale: Vehicle maintenance activities commonly release oils, fuels,
grease, and other petroleum products into stormwater runoff.
9. A field duplicate sample is primarily collected to evaluate:
A. Rainfall amount.
B. Laboratory certification.
C. Sampling precision.
D. Employee productivity.
Answer: C
Rationale: Duplicate samples help determine whether sampling and
analytical procedures produce consistent results.
10. Personal protective equipment (PPE) during stormwater
sampling should be selected based on:
A. Employee preference only.
B. Site-specific hazards and safety assessments.
C. Weather forecasts alone.
D. Laboratory requirements only.
Answer: B
Rationale: Appropriate PPE is determined through hazard assessment
considering chemical, biological, physical, and environmental risks.
Monitoring Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
Download Pdf
1.Under the National Pollutant Discharge Elimination System (NPDES) Multi-
Sector General Permit (MSGP), the primary purpose of stormwater sampling
is to:
A. Determine the value of industrial property.
B. Assess employee performance during storm events.
C. Evaluate whether stormwater discharges are being adequately controlled
and comply with permit requirements.
D. Measure groundwater recharge rates.
Answer: C
Rationale: Stormwater sampling under the NPDES program is intended to
evaluate the effectiveness of stormwater control measures, identify
potential pollutant sources, and determine compliance with permit
requirements.
2. Which of the following best describes a "measurable storm event" for
routine NPDES stormwater monitoring?
A. Any rainfall regardless of duration or amount.
B. A storm event meeting permit-defined criteria, often separated from
,previous measurable events by at least 72 hours.
C. Only storms producing more than 5 inches of rainfall.
D. Snowfall events only.
Answer: B
Rationale: Most NPDES permits define measurable storm events using
minimum precipitation thresholds and antecedent dry periods, commonly
requiring at least 72 hours between qualifying events.
3. Grab samples collected for stormwater monitoring should generally be
obtained:
A. At the end of the calendar month.
B. During the first flush or within the permit-specified timeframe after
discharge begins.
C. Only after laboratory approval.
D. After stormwater has infiltrated.
Answer: B
Rationale: The first flush often contains the highest pollutant
concentrations, making early sample collection essential for representative
monitoring.
4. Which parameter is commonly monitored because it indicates the
amount of suspended particulate matter in stormwater?
A. pH
B. Dissolved Oxygen
C. Total Suspended Solids (TSS)
D. Chloride
Answer: C
Rationale: TSS measures suspended particles that can transport pollutants,
reduce water clarity, and impact aquatic habitats.
, 5. The primary purpose of maintaining a chain-of-custody form is to:
A. Record employee attendance.
B. Document sample handling from collection through laboratory receipt.
C. Calculate rainfall intensity.
D. Measure stream flow.
Answer: B
Rationale: Chain-of-custody documentation preserves sample integrity by
recording every individual who handled the sample until laboratory
analysis.
6. Which instrument is commonly used to measure stormwater pH in the
field?
A. Radiation detector.
B. pH meter.
C. Spectrophotometer only.
D. Soil auger.
Answer: B
Rationale: Portable calibrated pH meters are widely used for field
measurement of stormwater acidity or alkalinity.
7. Why is equipment calibration important before stormwater sampling?
A. It increases rainfall.
B. It ensures measurement accuracy and defensible monitoring results.
C. It reduces permit fees.
D. It eliminates laboratory analysis.
Answer: B
Rationale: Calibration ensures instruments provide accurate
measurements that meet regulatory and quality assurance requirements.
, 8. Which stormwater pollutant is commonly associated with vehicle
maintenance areas?
A. Nutrients only.
B. Petroleum hydrocarbons.
C. Salt exclusively.
D. Pollen.
Answer: B
Rationale: Vehicle maintenance activities commonly release oils, fuels,
grease, and other petroleum products into stormwater runoff.
9. A field duplicate sample is primarily collected to evaluate:
A. Rainfall amount.
B. Laboratory certification.
C. Sampling precision.
D. Employee productivity.
Answer: C
Rationale: Duplicate samples help determine whether sampling and
analytical procedures produce consistent results.
10. Personal protective equipment (PPE) during stormwater
sampling should be selected based on:
A. Employee preference only.
B. Site-specific hazards and safety assessments.
C. Weather forecasts alone.
D. Laboratory requirements only.
Answer: B
Rationale: Appropriate PPE is determined through hazard assessment
considering chemical, biological, physical, and environmental risks.
