Certified Stormwater Manager (CSM) — Questions and Answers

Question 1: Which regulatory requirement mandates that states review and potentially revise their water quality standards at least every three years?

The Triennial Review under CWA Section 303(c) (Correct answer)
The Biennial Water Review under CWA Section 301
The Annual Permit Review under 40 CFR Part 122
The Five-Year Standards Update under CWA Section 402

Correct answer: The Triennial Review under CWA Section 303(c)

CWA Section 303(c) requires states to review and, if appropriate, revise their water quality standards at least once every three years — known as the Triennial Review.

Question 2: What is the term for the process of systematically closing down emergency operations and returning to normal stormwater management activities after a major incident?

Restoration
Remediation
Demobilization (Correct answer)
Incident stabilization

Correct answer: Demobilization

Demobilization in ICS refers to the planned, orderly release of resources and personnel and the return to pre-incident operational status.

Question 3: Which federal regulatory program is the primary driver requiring MS4 operators to develop and implement Illicit Discharge Detection and Elimination (IDDE) programs?

Resource Conservation and Recovery Act Subtitle D
Safe Drinking Water Act Surface Water Treatment Rule
Clean Water Act Section 401
NPDES Phase I and Phase II Stormwater Permit Program (Correct answer)

Correct answer: NPDES Phase I and Phase II Stormwater Permit Program

The NPDES Phase I and Phase II Stormwater Permit Program, under the Clean Water Act, requires regulated MS4 operators to develop IDDE programs as one of six minimum control measures.

Question 4: Which hydrologic term describes precipitation that is captured by vegetation and never reaches the ground surface?

Evaporation
Interception (Correct answer)
Stemflow
Throughfall

Correct answer: Interception

Interception is the process by which precipitation is caught and held by plant canopy, from which it evaporates before reaching the soil surface.

Question 5: The rational method formula Q = CiA requires that the storm duration equal the time of concentration because:

The rational coefficient C changes with storm duration
The entire watershed contributes runoff simultaneously at peak flow (Correct answer)
Shorter storms produce higher peak flows
Longer storms produce more total runoff volume

Correct answer: The entire watershed contributes runoff simultaneously at peak flow

When storm duration equals time of concentration, all parts of the watershed are contributing simultaneously, producing the maximum peak discharge for that rainfall intensity.

Question 6: What is a level spreader in stormwater management?

A structure that converts concentrated stormwater flow into sheet flow and distributes it uniformly across a vegetated filter strip (Correct answer)
A filter media layer in a bioretention cell that distributes water evenly through the root zone
A mechanical actuator that maintains constant water levels in a retention pond
A device that measures the elevation of water in a detention pond

Correct answer: A structure that converts concentrated stormwater flow into sheet flow and distributes it uniformly across a vegetated filter strip

A level spreader is a constructed outlet structure that takes concentrated stormwater flow and spreads it as thin sheet flow across a vegetated filter strip or buffer, reducing velocity and improving infiltration and filtration.

Question 7: What is infiltration used for in BMPs?

To prevent evaporation.
To increase surface runoff.
To allow water to enter the soil (Correct answer)
To speed up drainage into sewers.

Correct answer: To allow water to enter the soil

Infiltration in BMPs refers to the process where stormwater is allowed to soak into the ground, rather than running off the surface. This technique helps to replenish groundwater, reduce the volume of surface runoff, and filter out pollutants naturally through the soil layers. It is a key component of sustainable stormwater management, mimicking natural hydrological cycles.

Question 8: After a chemical spill enters a stormwater outfall, what is the required reporting timeframe to the National Response Center (NRC) for a reportable quantity release?

Within 24 hours of discovery
Within 72 hours of discovery
Within the next business day
Immediately upon discovery (Correct answer)

Correct answer: Immediately upon discovery

CERCLA and the Clean Water Act require immediate notification to the NRC (1-800-424-8802) when a reportable quantity of a hazardous substance is released to navigable waters.

Question 9: Under the EPA Multi-Sector General Permit (MSGP), which sector group typically requires benchmark monitoring for pH, total suspended solids, and chemical oxygen demand?

Sector A – Timber Products
Sector S – Air Transportation
Sector C – Chemical and Allied Products (Correct answer)
Sector M – Automobile Salvage Yards

Correct answer: Sector C – Chemical and Allied Products

Sector C (Chemical and Allied Products) facilities typically face monitoring requirements for pH, TSS, COD, and sector-specific pollutants due to the chemical nature of their operations.

Question 10: What is a vegetative BMP example?

Grassed swales and rain gardens (Correct answer)
Storm grates.
Culverts.
Concrete channels.

Correct answer: Grassed swales and rain gardens

Grassed swales and rain gardens are excellent examples of vegetative BMPs. These systems utilize plants and engineered soil media to filter pollutants, absorb stormwater, and promote infiltration into the ground. They mimic natural processes to manage runoff, enhance water quality, and often provide aesthetic and habitat benefits.

Question 11: During a flash flood emergency, a stormwater manager should use which communication protocol to ensure field crews receive consistent instructions?

Technical jargon specific to the stormwater profession
Plain language standardized under NIMS/ICS protocols (Correct answer)
Informal phone calls between supervisors and crews
Social media posts visible to the public

Correct answer: Plain language standardized under NIMS/ICS protocols

NIMS requires the use of plain language (clear text) during emergency communications to prevent miscommunication across agencies and disciplines.

Question 12: Which performance metric best evaluates a BMP's effectiveness at reducing nutrient loads to receiving waters?

Manning's n value of the BMP outlet channel
Event mean concentration (EMC) reduction for total nitrogen and total phosphorus (Correct answer)
Total impervious surface area treated per acre of BMP footprint
Peak flow reduction ratio between inflow and outflow hydrographs

Correct answer: Event mean concentration (EMC) reduction for total nitrogen and total phosphorus

Event mean concentration reductions for total nitrogen and total phosphorus directly measure the BMP's ability to remove the pollutants of concern for nutrient-impaired receiving waters.

Question 13: What is the term for the portion of precipitation that eventually reaches a stream channel through shallow subsurface flow?

Deep percolation
Interflow (Correct answer)
Baseflow
Overland flow

Correct answer: Interflow

Interflow (also called subsurface stormflow or throughflow) moves laterally through the upper soil horizons and contributes to streamflow during and shortly after storms.

Question 14: Which stormwater-related permit condition requires operators to develop and implement a written plan describing BMPs for their site?

Notice of Intent (NOI)
Best Management Practice Schedule
Effluent Limitation Guideline
Stormwater Pollution Prevention Plan (SWPPP) (Correct answer)

Correct answer: Stormwater Pollution Prevention Plan (SWPPP)

A SWPPP is a site-specific written plan required under most NPDES stormwater permits that identifies potential pollutant sources and the BMPs used to control them.

Question 15: A watershed with a curve number (CN) of 90 compared to one with CN of 60 will produce:

More infiltration and less surface flow
Less runoff for the same rainfall event
More runoff for the same rainfall event (Correct answer)
The same runoff but with longer time to peak

Correct answer: More runoff for the same rainfall event

Higher curve numbers indicate less permeable, more developed or compacted land, resulting in greater direct runoff for the same precipitation event.

Question 16: What is green infrastructure in the context of urban stormwater management?

Painting stormwater infrastructure green to indicate environmental compliance
Installing solar panels on top of stormwater detention facilities
An approach that uses natural processes and vegetation to manage stormwater at or near its source, mimicking the natural water cycle (Correct answer)
Using recycled materials in the construction of storm sewer pipes

Correct answer: An approach that uses natural processes and vegetation to manage stormwater at or near its source, mimicking the natural water cycle

Green infrastructure uses vegetated systems such as rain gardens, bioretention cells, and green roofs to infiltrate, evapotranspirate, or filter stormwater close to where rain falls, reducing runoff volume and improving water quality.

Question 17: When documenting an IDDE field investigation, which of the following is MOST important to record for potential enforcement action?

The estimated annual pollutant load from the discharge
Photographic evidence, GPS coordinates, field measurements, time and date of observation, and the name of the inspector (Correct answer)
The weather forecast for the following week
Only the address of the suspected source facility

Correct answer: Photographic evidence, GPS coordinates, field measurements, time and date of observation, and the name of the inspector

Thorough documentation including photos, GPS location, field measurements, timestamps, and inspector identification is essential for creating a defensible enforcement record and tracking investigation status.

Question 18: What tool is used to guide inspection frequency and procedure?

Sign-in sheet.
Blueprint diagram.
Inspection checklist (Correct answer)
Project invoice.

Correct answer: Inspection checklist

An inspection checklist is a vital tool used to guide the frequency and procedure of stormwater inspections. It provides a systematic framework, ensuring that all necessary components and criteria are consistently reviewed during each inspection. This standardization helps maintain thoroughness, consistency, and compliance with regulatory requirements.

Question 19: Which CWA provision regulates the discharge of dredge or fill material into waters of the United States, including wetlands that may affect stormwater flow?

Section 401
Section 319
Section 402
Section 404 (Correct answer)

Correct answer: Section 404

CWA Section 404 authorizes the U.S. Army Corps of Engineers (with EPA oversight) to regulate discharge of dredged or fill material into waters of the US, including wetlands.

Question 20: What is the primary purpose of a silt fence installed at a construction site?

To direct stormwater into underground pipes
To intercept sediment-laden runoff and allow sediment to settle before water leaves the site (Correct answer)
To prevent workers from entering hazardous zones
To mark property boundaries during construction

Correct answer: To intercept sediment-laden runoff and allow sediment to settle before water leaves the site

A silt fence is a temporary sediment control device that intercepts sheet flow runoff, slowing it down so suspended sediment can settle out before the water leaves the site.

Question 21: In NRCS TR-55 methodology, which of the following contributes to the 'sheet flow' portion of time of concentration calculation?

Flow in storm sewers and culverts
Subsurface flow through soil macropores
Overland flow on unpaved or paved surfaces for distances up to 300 feet (Correct answer)
Flow in defined natural or constructed channels

Correct answer: Overland flow on unpaved or paved surfaces for distances up to 300 feet

Sheet flow is the initial overland flow phase, occurring over plane surfaces (grass, pavement, bare soil) for distances up to 300 feet before concentrating into shallow concentrated flow or channels.

Question 22: A stormwater inspector observes that the riprap apron at a culvert outlet has experienced significant displacement, with large stones scattered downstream. What hydrodynamic condition most likely caused this failure?

Vandalism as the primary cause in most urban settings
Biological activity from beaver damming upstream
Outlet scour velocity exceeding the riprap's design D50 stone size resistance, indicating undersized riprap or insufficient apron length (Correct answer)
Frost heave lifting individual stones during winter

Correct answer: Outlet scour velocity exceeding the riprap's design D50 stone size resistance, indicating undersized riprap or insufficient apron length

Riprap displacement at a culvert outlet is classic evidence of scour velocities exceeding the riprap's hydraulic resistance, typically caused by undersized stone (D50 too small) or an apron shorter than the energy dissipation zone.

Question 23: Which document must a construction general permit operator post at the construction site entrance?

A Tier 2 corrective action report
A copy of the facility's DMR
The TMDL wasteload allocation for the receiving water
The permit coverage confirmation or NOI acknowledgment with permit tracking number (Correct answer)

Correct answer: The permit coverage confirmation or NOI acknowledgment with permit tracking number

Operators must post the permit tracking number or NOI acknowledgment at the construction site entrance to show permit coverage.

Question 24: Which of the following represents a structural BMP rather than a non-structural (source control) BMP?

Detention pond (Correct answer)
Illicit discharge detection and elimination ordinance
Street sweeping program
Fertilizer application restrictions

Correct answer: Detention pond

Detention ponds are engineered, constructed facilities (structural BMPs), while the other options are programmatic or regulatory measures (non-structural BMPs).

Question 25: What is the recommended approach for tracing an illicit discharge upstream once flow is confirmed at an outfall during dry weather?

Sample the outfall water and wait for laboratory results before any field work
Install automated samplers at the outfall and review data remotely
Walk the contributing drainage area and systematically check manholes and inlets moving upstream (Correct answer)
Issue violation notices to all businesses in the drainage area

Correct answer: Walk the contributing drainage area and systematically check manholes and inlets moving upstream

Systematic upstream manhole and inlet investigation — walking the system from the outfall — is the standard IDDE field methodology to isolate the source of an illicit discharge.

Question 26: What does NPDES stand for?

National Pollutant Discharge Elimination System (Correct answer)
National Pipeline Drainage Emergency Service.
Neutral Pressure Drainage Efficiency System.
National Permit for Dry Emissions Standards.

Correct answer: National Pollutant Discharge Elimination System

NPDES stands for National Pollutant Discharge Elimination System. This is a permitting program under the Clean Water Act that controls direct discharges of pollutants into U.S. waters. Facilities that discharge pollutants from a point source into waters of the United States are required to obtain an NPDES permit.

Question 27: What is hydroseeding as an erosion control method?

The use of water jets to remove invasive vegetation from slopes
Chemical treatment applied to harden soil surfaces against rainfall impact
A process that sprays a slurry of seed, mulch, fertilizer, and water onto disturbed soil to establish vegetation quickly (Correct answer)
A method of irrigating newly planted slopes with subsurface drip lines

Correct answer: A process that sprays a slurry of seed, mulch, fertilizer, and water onto disturbed soil to establish vegetation quickly

Hydroseeding applies a hydraulically sprayed mixture of seed, mulch, fertilizer, and sometimes tackifier to rapidly establish vegetative cover on disturbed areas.

Question 28: What does the term 'effluent limitation guideline' (ELG) mean in the context of stormwater documentation?

A TMDL wasteload allocation for a specific watershed
A technology-based standard limiting pollutant concentrations in stormwater discharges by industrial category (Correct answer)
A state-specific BMR for municipal stormwater
A recommended BMP for sediment control

Correct answer: A technology-based standard limiting pollutant concentrations in stormwater discharges by industrial category

ELGs are EPA-established technology-based standards that set pollutant discharge limits for specific categories of industrial facilities.

Question 29: Which of the following best describes the role of public education and outreach in an effective IDDE program?

It serves primarily to meet permit reporting requirements with minimal operational impact
It reduces illicit discharges by informing residents and businesses about what can legally enter storm drains and how to report illegal dumping (Correct answer)
It is only required for Phase I MS4 permits in large urban areas
It is the responsibility of the state environmental agency, not the MS4 operator

Correct answer: It reduces illicit discharges by informing residents and businesses about what can legally enter storm drains and how to report illegal dumping

Public education and outreach reduce illicit discharges by raising awareness of proper disposal practices and creating a community reporting network that extends the reach of limited inspection staff.

Question 30: Which method is used to assess soil infiltration capacity in the field for green infrastructure siting?

Falling head permeameter test (Correct answer)
Acoustic Doppler velocimetry
Secchi disk measurement
Total organic carbon analysis

Correct answer: Falling head permeameter test

A falling head permeameter (or double-ring infiltrometer) measures the rate at which water infiltrates into the soil, which is critical for sizing infiltration-based BMPs.

Certified Stormwater Manager (CSM)

The CSM certification, administered by APWA, validates professional competency in municipal stormwater program management including regulatory compliance, hydrology, erosion and sediment control, illicit discharge elimination, BMP design, and program administration.

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35 min

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70%

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