NPDES LEVEL 1A CERTIFICATION TEST QUESTIONS & ANSWERS 2026-2027 | …
P R O F E S S I O N A L P R A C T I C E M AT E R I A L S
NPDES Level 1A
Certification Test Questions
& Answers 2026-2027 |
Updated Exam Review
(Rationales)
Verified Answers Exam Ready With Rationales 50 QUESTIONS
DOCUMENT OVERVIEW
This document provides 50 NPDES Level 1A certification review questions with pre-
supplied correct answers and detailed rationales. It covers essential stormwater
management principles, serving as an effective study and review tool for individuals
preparing for their Level 1A certification.
TOPICS
Erosion and Sediment Control Principles Q1–Q13
Permitting and Regulatory Compliance Q14–Q20
Best Management Practices (BMPs) Design & Maintenance Q21–Q31
Acronyms and Definitions Q32–Q50
Page 1
, E XA M Q U EST I O N S
Q1 QUESTION 1 OF 50
A slope gradient of 25% (4:1) would indicate that in a horizontal length of 100 feet, the
vertical rise would be ______ feet.
A) 2.5
B) 12.5
C) 25
D) 4
CORRECT ANSWER
C) 25
RATIONALE
A slope gradient of 25% means that for every 100 units of horizontal distance, there is a 25-unit
vertical rise. Therefore, in a horizontal length of 100 feet, the vertical rise is 25 feet.
Q2 QUESTION 2 OF 50
As rain falls to the earth, what is the very first function of vegetation?
A) It reduces detachment
B) It increases infiltration
C) It absorbs rain drop impact
D) Roots hold soil in place
CORRECT ANSWER
A) It reduces detachment
RATIONALE
Vegetation's first function upon rainfall is to intercept raindrops, thus reducing their direct impact
on the soil surface. This interception, or reduction of detachment, prevents soil particles from
becoming dislodged and being washed away.
Page 2
, Q3 QUESTION 3 OF 50
Because of the likelihood of thunderstorms which is the worst month to schedule land
disturbing activities?
A) April
B) July
C) September
D) October
CORRECT ANSWER
B) July
RATIONALE
Thunderstorms are most frequent during the summer months when atmospheric instability is
highest. July falls squarely within this period of peak thunderstorm activity, making it the month
with the greatest likelihood of severe weather events that could disrupt land-disturbing activities.
Q4 QUESTION 4 OF 50
Which of the following is not a stage in Erosion and Sedimentation?
A) Detachment
B) Solubility
C) Transport
D) Deposition
CORRECT ANSWER
B) Solubility
RATIONALE
Erosion and sedimentation are processes involving the detachment of soil particles, their transport
by agents like water or wind, and subsequent deposition. Solubility refers to the ability of a
substance to dissolve in a solvent and is not a direct stage in the physical process of erosion and
sedimentation.
Page 3
P R O F E S S I O N A L P R A C T I C E M AT E R I A L S
NPDES Level 1A
Certification Test Questions
& Answers 2026-2027 |
Updated Exam Review
(Rationales)
Verified Answers Exam Ready With Rationales 50 QUESTIONS
DOCUMENT OVERVIEW
This document provides 50 NPDES Level 1A certification review questions with pre-
supplied correct answers and detailed rationales. It covers essential stormwater
management principles, serving as an effective study and review tool for individuals
preparing for their Level 1A certification.
TOPICS
Erosion and Sediment Control Principles Q1–Q13
Permitting and Regulatory Compliance Q14–Q20
Best Management Practices (BMPs) Design & Maintenance Q21–Q31
Acronyms and Definitions Q32–Q50
Page 1
, E XA M Q U EST I O N S
Q1 QUESTION 1 OF 50
A slope gradient of 25% (4:1) would indicate that in a horizontal length of 100 feet, the
vertical rise would be ______ feet.
A) 2.5
B) 12.5
C) 25
D) 4
CORRECT ANSWER
C) 25
RATIONALE
A slope gradient of 25% means that for every 100 units of horizontal distance, there is a 25-unit
vertical rise. Therefore, in a horizontal length of 100 feet, the vertical rise is 25 feet.
Q2 QUESTION 2 OF 50
As rain falls to the earth, what is the very first function of vegetation?
A) It reduces detachment
B) It increases infiltration
C) It absorbs rain drop impact
D) Roots hold soil in place
CORRECT ANSWER
A) It reduces detachment
RATIONALE
Vegetation's first function upon rainfall is to intercept raindrops, thus reducing their direct impact
on the soil surface. This interception, or reduction of detachment, prevents soil particles from
becoming dislodged and being washed away.
Page 2
, Q3 QUESTION 3 OF 50
Because of the likelihood of thunderstorms which is the worst month to schedule land
disturbing activities?
A) April
B) July
C) September
D) October
CORRECT ANSWER
B) July
RATIONALE
Thunderstorms are most frequent during the summer months when atmospheric instability is
highest. July falls squarely within this period of peak thunderstorm activity, making it the month
with the greatest likelihood of severe weather events that could disrupt land-disturbing activities.
Q4 QUESTION 4 OF 50
Which of the following is not a stage in Erosion and Sedimentation?
A) Detachment
B) Solubility
C) Transport
D) Deposition
CORRECT ANSWER
B) Solubility
RATIONALE
Erosion and sedimentation are processes involving the detachment of soil particles, their transport
by agents like water or wind, and subsequent deposition. Solubility refers to the ability of a
substance to dissolve in a solvent and is not a direct stage in the physical process of erosion and
sedimentation.
Page 3
