CSM Cheat Sheet 2026

The 30 highest-yield CSM facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Tree canopy interception contributes to stormwater management primarily by: → Temporarily storing rainfall on leaves and branches before evaporation
2. What is the primary purpose of using a Manning's n roughness coefficient in stormwater assessment? → Calculating open-channel flow velocity
3. A municipality installs permeable pavers in a parking lot. What is the MOST direct hydrologic benefit? → Reduced surface runoff volume
4. When sizing a vegetated filter strip for stormwater pretreatment, which parameter is most critical for determining the required width? → Hydraulic loading rate per unit width
5. Which metric best evaluates whether a Low Impact Development (LID) design meets volume-based runoff performance standards? → Runoff volume retention or capture depth
6. When using an ultrasonic level sensor to measure water depth at a stormwater outfall, what environmental condition most commonly causes measurement errors? → Floating debris or foam on the water surface
7. What is base flow in a stream? → Groundwater contribution to stream flow
8. Which condition would most likely trigger a requirement to develop a Corrective Action Report under the EPA Construction General Permit? → Discovering that a BMP has failed to perform as designed and a discharge occurred
9. Which channel lining material provides the highest Manning's n roughness value and therefore the slowest flow velocities for a given channel geometry and slope? → Dense grass
10. A stormwater manager needs to assess the condition of a buried culvert without excavation. Which method is most appropriate? → CCTV pipe inspection
11. What is the most important principle in professional Certified Stormwater Manager practice? → Maintaining competence through continuous learning and adherence to standards
12. Which analytical method is approved under 40 CFR Part 136 for measuring total suspended solids (TSS) in stormwater samples? → EPA Method 160.2 (gravimetric filtration and drying)
13. What is hydrology the study of? → Water movement and distribution
14. What is the primary purpose of a unit hydrograph in stormwater hydrology? → To relate a unit depth of excess rainfall to a direct runoff hydrograph for a watershed
15. What is the significance of professional networking in the Certified Stormwater Manager field? → It facilitates knowledge exchange, referrals, and collaborative problem-solving
16. When assessing vulnerability of stormwater infrastructure to extreme weather events, which approach provides the most comprehensive risk picture? → Combining hydraulic modeling, infrastructure condition assessment, and climate projections
17. Evapotranspiration (ET) is typically highest in watersheds that have: → Dense vegetation, warm temperatures, and ample soil moisture
18. A construction site operator discovers a non-stormwater discharge of concrete washout water entering a storm drain. What is the first documentation step? → Record the incident in the site's inspection log and initiate corrective action
19. What is the goal of erosion control in construction sites? → To prevent soil loss and pollution
20. Which type of emergency drill is most effective for testing a stormwater response plan's field logistics, equipment deployment, and crew coordination? → Full-scale functional exercise
21. How should a Certified Stormwater Manager professional handle situations beyond their expertise? → Refer to a qualified specialist and communicate transparently with the client
22. What is a watershed? → A land area draining into a water body
23. Which stormwater-related permit condition requires operators to develop and implement a written plan describing BMPs for their site? → Stormwater Pollution Prevention Plan (SWPPP)
24. A stormwater manager reviews a stage-discharge rating curve for a stream monitoring station. What condition would cause the curve to be unreliable? → Shifting channel bed due to scour and deposition
25. What is infiltration? → Water soaking into the soil
26. What is the primary purpose of a Job Hazard Analysis (JHA) completed before stormwater field inspections? → To identify and mitigate task-specific hazards before work begins
27. How should a Certified Stormwater Manager professional handle situations beyond their expertise? → Refer to a qualified specialist and communicate transparently with the client
28. What does a specific conductance reading that is significantly higher than background levels indicate during dry-weather screening? → Possible presence of dissolved salts or wastewater in the flow
29. Why is watershed management important? → To support water quality and ecosystems
30. Which method is used to assess soil infiltration capacity in the field for green infrastructure siting? → Falling head permeameter test