NPDES Stormwater Outfall Inspection
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1.Which of the following best describes the primary purpose of conducting
an NPDES stormwater outfall inspection?
A. To increase water pressure within the storm sewer system
B. To determine whether stormwater discharges comply with permit
requirements and do not adversely impact receiving waters
C. To evaluate sanitary sewer treatment efficiency
D. To inspect drinking water distribution systems
Rationale: The primary objective of an NPDES stormwater outfall
inspection is to verify compliance with permit requirements, identify
pollutants entering receiving waters, and ensure protection of water
quality under the Clean Water Act.
2. Which federal law established the National Pollutant Discharge
Elimination System (NPDES)?
A. Safe Drinking Water Act
B. Resource Conservation and Recovery Act
C. Clean Air Act
D. Clean Water Act
,Rationale: The Clean Water Act established the NPDES program to regulate
pollutant discharges into waters of the United States through a permitting
system.
3. During a dry weather inspection, continuous flow from a stormwater
outfall most commonly indicates:
A. Normal rainfall runoff
B. A potential illicit discharge requiring investigation
C. Proper system operation
D. Seasonal groundwater recharge only
Rationale: Stormwater systems should generally not discharge during
prolonged dry weather. Continuous flow often indicates an illicit
connection or unauthorized discharge that requires further investigation.
4. Which observation is generally considered the strongest visual
indicator of an illicit discharge?
A. Clear water with no odor
B. Minor sediment deposits after rainfall
C. Sewage odor accompanied by gray or black flow
D. Small amounts of leaves
Rationale: Gray or black water with a sewage odor strongly suggests
sanitary wastewater entering the storm drainage system through an illicit
connection.
5. Which equipment is most essential for documenting outfall conditions
during an inspection?
A. Welding machine
B. Pressure washer
C. Camera or mobile device with photographic capability
D. Soil compactor
, Rationale: Photographs provide objective documentation of site
conditions and support inspection reports and enforcement actions.
6. What should be reviewed before conducting an outfall inspection?
A. Employee payroll records
B. Building floor plans only
C. Applicable permits, maps, previous inspection reports, and drainage
information
D. Water treatment chemical inventories
Rationale: Reviewing available records helps inspectors understand site
history, drainage patterns, previous violations, and permit requirements
before arriving on site.
7. The receiving water is best defined as:
A. A wastewater treatment basin
B. The stream, river, lake, wetland, or other waterbody receiving the
discharge
C. A drinking water reservoir only
D. A groundwater monitoring well
Rationale: Receiving waters are the natural water bodies into which
permitted stormwater discharges ultimately flow.
8. Which field parameter can be measured immediately using a portable
meter?
A. Total suspended solids only
B. Biological oxygen demand
C. pH
D. Total phosphorus
Rationale: Portable meters commonly measure pH directly in the field,
allowing inspectors to identify abnormal discharge characteristics
immediately.
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download
1.Which of the following best describes the primary purpose of conducting
an NPDES stormwater outfall inspection?
A. To increase water pressure within the storm sewer system
B. To determine whether stormwater discharges comply with permit
requirements and do not adversely impact receiving waters
C. To evaluate sanitary sewer treatment efficiency
D. To inspect drinking water distribution systems
Rationale: The primary objective of an NPDES stormwater outfall
inspection is to verify compliance with permit requirements, identify
pollutants entering receiving waters, and ensure protection of water
quality under the Clean Water Act.
2. Which federal law established the National Pollutant Discharge
Elimination System (NPDES)?
A. Safe Drinking Water Act
B. Resource Conservation and Recovery Act
C. Clean Air Act
D. Clean Water Act
,Rationale: The Clean Water Act established the NPDES program to regulate
pollutant discharges into waters of the United States through a permitting
system.
3. During a dry weather inspection, continuous flow from a stormwater
outfall most commonly indicates:
A. Normal rainfall runoff
B. A potential illicit discharge requiring investigation
C. Proper system operation
D. Seasonal groundwater recharge only
Rationale: Stormwater systems should generally not discharge during
prolonged dry weather. Continuous flow often indicates an illicit
connection or unauthorized discharge that requires further investigation.
4. Which observation is generally considered the strongest visual
indicator of an illicit discharge?
A. Clear water with no odor
B. Minor sediment deposits after rainfall
C. Sewage odor accompanied by gray or black flow
D. Small amounts of leaves
Rationale: Gray or black water with a sewage odor strongly suggests
sanitary wastewater entering the storm drainage system through an illicit
connection.
5. Which equipment is most essential for documenting outfall conditions
during an inspection?
A. Welding machine
B. Pressure washer
C. Camera or mobile device with photographic capability
D. Soil compactor
, Rationale: Photographs provide objective documentation of site
conditions and support inspection reports and enforcement actions.
6. What should be reviewed before conducting an outfall inspection?
A. Employee payroll records
B. Building floor plans only
C. Applicable permits, maps, previous inspection reports, and drainage
information
D. Water treatment chemical inventories
Rationale: Reviewing available records helps inspectors understand site
history, drainage patterns, previous violations, and permit requirements
before arriving on site.
7. The receiving water is best defined as:
A. A wastewater treatment basin
B. The stream, river, lake, wetland, or other waterbody receiving the
discharge
C. A drinking water reservoir only
D. A groundwater monitoring well
Rationale: Receiving waters are the natural water bodies into which
permitted stormwater discharges ultimately flow.
8. Which field parameter can be measured immediately using a portable
meter?
A. Total suspended solids only
B. Biological oxygen demand
C. pH
D. Total phosphorus
Rationale: Portable meters commonly measure pH directly in the field,
allowing inspectors to identify abnormal discharge characteristics
immediately.
