Free SWPPP & Stormwater Practice Test (NPDES / CGP Quiz)

This practice test pulls questions from all 12 free lessons. It is a study aid, not an exam for a certificate or a state credential, and your answers are never stored.

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Stormwater practice test: 20 random questions

Each attempt draws 20 questions from the 96-question bank built from our free lessons. Score 80% or higher to pass. Select New random test for a fresh set. Nothing you answer is saved or sent.

Question 1 Where does water entering a typical street storm drain go?

Always to a wastewater treatment plantUsually directly to local streams, rivers, lakes or bays, often without treatmentInto the drinking water supply after filteringInto the sanitary sewer

Question 2 What pollutant do construction sites typically release in the largest amounts?

BacteriaMetalsSedimentTrash

Question 3 Why is concrete washout water a stormwater concern?

It is highly alkaline (high pH) and harmful to aquatic lifeIt contains bacteriaIt cools the receiving waterIt is not a concern

Question 4 Which is an effect of sediment in a stream?

Increased sunlight for plantsSmothering fish spawning beds and carrying attached pollutantsLower flooding riskCleaner water downstream

Question 5 Which type of control keeps soil from being dislodged in the first place?

Erosion control, such as mulch, blankets and vegetationSediment control, such as silt fenceInlet protectionA sediment basin

Question 6 Why is erosion control generally more effective than sediment control?

It's cheaper to install every timePreventing soil from moving is easier than trying to catch fine particles once they're suspended in runoffOSHA requires itSediment control is never effective

Question 7 Construction activities that disturb how much land generally need NPDES stormwater permit coverage?

10 acres or more5 acres or more only1 acre or more, or less than 1 acre if part of a larger common plan that disturbs 1 acre or moreAny amount

Question 8 Which practice addresses runoff that has concentrated and is cutting rills and gullies?

Portable toilet placementSlope breaks, check dams and velocity dissipationStockpile labelingTrash pickup

Question 9 Which section of the Clean Water Act creates the NPDES permit program?

Section 101Section 303Section 402Section 404

Question 10 What does NPDES stand for?

National Pollutant Discharge Elimination SystemNational Plan for Drainage and Erosion StandardsNatural Pollution Detection and Enforcement ServiceNational Permit for Development and Excavation Sites

Question 11 Phase II of EPA's stormwater rules extended construction permit coverage to sites disturbing how much land?

10 acres or more1 to 5 acresLess than 1 acre only50 acres or more

Question 12 In most states, who issues construction stormwater permits?

The U.S. Army Corps of EngineersA state agency authorized by EPA to run the NPDES programOSHAThe local building inspector

Question 13 How does a construction site typically obtain coverage under a general permit?

By calling 811By submitting a Notice of Intent (NOI)By posting a signCoverage is automatic

Question 14 When does EPA's 2022 Construction General Permit expire?

December 31, 202511:59 p.m. on February 16, 2027It never expiresFebruary 17, 2032

Question 15 What is the key compliance document for construction stormwater permits?

The building permitThe Stormwater Pollution Prevention Plan (SWPPP)The grading plan onlyThe OSHA 300 log

Question 16 Which of these is NOT one of the three main NPDES stormwater programs?

ConstructionMunicipal separate storm sewer systems (MS4)IndustrialResidential lawn watering

Question 17 A project will disturb 0.6 acres, but it is part of a subdivision that will disturb 12 acres. Does it need coverage?

No, it's under one acreYes, it's part of a larger common plan of development that will disturb more than one acreOnly if it rains during constructionOnly if the lot is next to a stream

Question 18 Under the EPA CGP, which parties are operators?

Only the excavation subcontractorThe party with control over plans and specifications and the party with day-to-day operational controlOnly the property ownerOnly the engineer of record

Question 19 Under the EPA CGP, when must the SWPPP be prepared?

Within 30 days after construction startsBefore submitting the Notice of IntentOnly if an inspector requests itAfter final stabilization

Question 20 Under the EPA CGP, how far in advance of construction must a new site submit its NOI?

The day construction startsAt least 14 calendar days before commencing construction activities90 daysNo NOI is needed

Question 21 When does EPA CGP coverage begin for a new site?

14 calendar days after EPA notifies the operator that it received a complete NOI, unless delayed or deniedImmediately when the NOI is submittedAfter the first inspection30 days after the SWPPP is signed

Question 22 Which sites may qualify for the low erosivity waiver?

Any site in a dry stateSites disturbing 1 to less than 5 acres where the rainfall erosivity factor (R) is less than 5 for the construction periodSites over 50 acresSites with no streams nearby

Question 23 Within how many days must a Notice of Termination be submitted after a termination condition occurs?

7 calendar days14 calendar days30 calendar days1 year

Question 24 Under the modified 2022 CGP, what must accompany an NOT based on completing construction?

A copy of the building permitBefore and after photographs documenting final stabilizationA soil lab reportThe owner's tax ID

Question 25 Under the EPA CGP, when must the SWPPP be developed?

Before the Notice of Intent is submittedWithin 30 days after construction startsOnly for sites over 5 acresAfter the first inspection

Question 26 Which item belongs on the SWPPP site map?

The project's financing detailsLocations of all stormwater controls, stockpiles, washouts and discharge pointsEmployee home addressesThe building's interior floor plan

Question 27 Who must be identified in the SWPPP's stormwater team section?

Only the property ownerThe personnel responsible for permit compliance, including those who install and maintain controls, inspect and take corrective actionsThe local fire chiefEvery subcontractor's employees

Question 28 Under the EPA CGP, for coverage on or after February 17, 2023, what makes an inspector a "qualified person"?

Any employee with a hard hatCompleting EPA's construction inspection course for the permit and passing the exam, or holding a current valid certification from a program covering the required topicsA professional engineering license onlyCalifornia QSP status only

Question 29 After a corrective action changes a control described in the SWPPP, how quickly must the SWPPP be modified under the EPA CGP?

Within 24 hoursWithin 7 calendar days of completing the workAt the end of the projectWithin 1 year

Question 30 How long must the SWPPP and related records be kept under the EPA CGP?

90 days1 yearAt least 3 years from when coverage expires or is terminated30 years

Question 31 Who signs the SWPPP certification?

The operator's authorized signatoryAny laborer on siteThe local building inspectorThe storm drain manufacturer

Question 32 Which is an authorized non-stormwater discharge that the SWPPP may need to address?

Concrete washout waterFuel spillsUncontaminated construction dewatering water discharged per the permitPaint cleanup water

Question 33 What is the main purpose of erosion control?

Keep soil from being detached and moved in the first placeCatch sediment after it leaves the siteTreat stormwater chemicallyPump water off the site

Question 34 Why is phasing construction an effective erosion control practice?

It increases the area exposed at onceIt limits how much soil is exposed at any one timeIt removes the need for a SWPPPIt speeds up grading

Question 35 Which practice is best suited to a steep slope that needs immediate cover?

Plastic sheeting over the entire slope permanentlyAn erosion control blanket or bonded fiber matrixSilt fence at the top of the slopeLeaving it bare until final grading

Question 36 How should tracked equipment be run when roughening a slope?

Across the slope, so cleat marks run up and downUp and down the slope, so cleat marks run across itIn circlesIt doesn't matter

Question 37 Under the EPA CGP, when must stabilization be initiated in an area that will be inactive for 14 or more days?

Within 30 daysImmediately, meaning no later than the end of the next business dayOnly at the end of the projectWithin 14 days

Question 38 A site keeps disturbance to 4 acres at a time and discharges to an unimpaired water. How long does it have to complete stabilization after initiating it under the EPA CGP?

3 days7 days14 calendar days30 days

Question 39 What does a check dam do?

Stores water for irrigationSlows flow in a swale or ditch to reduce channel erosionRemoves oil from runoffBlocks traffic

Question 40 Why does the EPA CGP require dust control on exposed soil?

To keep equipment cleanWind-blown dust settles into drainage paths and becomes sediment in stormwaterDust is a hazardous wasteIt's only an air permit issue

Question 41 Under the EPA CGP, when must sediment be removed from a perimeter control?

When it reaches the top of the fenceBefore it accumulates to one-half of the above-ground height of the controlOnly at the end of the projectOnce a month

Question 42 How should the ends of a perimeter control be installed?

Straight across the slope with ends pointing downhillExtended up slope, for example at 45 degrees, forming a crescent so water can't flow around the endsOverlapped by 1 inchBuried completely

Question 43 Where is silt fence NOT appropriate?

Along the downslope perimeter of a graded lotAcross a ditch or swale carrying concentrated flowBelow a stockpileAt the toe of a short slope

Question 44 Mud is tracked onto a public street on a Tuesday. When must it be removed under the EPA CGP?

Within 7 daysBy the end of the same business dayAt the end of the projectOnly if a neighbor complains

Question 45 Which method of removing track-out is prohibited?

Sweeping it upVacuuming itHosing it into a storm drain inletShoveling it into a truck

Question 46 What storage must a sediment basin provide under the EPA CGP?

1,000 cubic feet per acre drainedEither the runoff from a 2-year, 24-hour storm or 3,600 cubic feet per acre drainedThe 100-year storm volumeAny size the contractor chooses

Question 47 Why should sediment basin outlets withdraw water from the surface?

The cleanest water, with the least suspended sediment, is at the surfaceIt's cheaperIt drains the basin fasterIt keeps the basin full

Question 48 A soil stockpile won't be used for three weeks. What does the EPA CGP require?

NothingCover or temporary stabilization, plus a sediment barrier on the downgradient sidesMove it next to the storm drainSpray it with water once

Question 49 Under the EPA CGP, what must concrete washout water be directed into?

The nearest storm drainA gravel area to soak inA leak-proof container or leak-proof, lined pit designed not to overflowThe street gutter

Question 50 Why is concrete washout water harmful to waterways?

It's too coldIt's highly alkaline (high pH) and carries fine cement particlesIt contains sugarIt isn't harmful

Question 51 Which discharge does the EPA CGP prohibit?

Uncontaminated dewatering water discharged per the permitSoaps or detergents used in equipment washingStormwater that passed through a sediment basinClean water from a fire hydrant flush, if authorized

Question 52 Where should equipment fueling take place?

In a designated area away from drainage features and inlets, with spill kits availableNext to the storm drain for easy cleanupAnywhere on siteIn the sediment basin

Question 53 Where should a concrete washout be located?

As close to a storm drain inlet as possibleAs far away as possible from receiving waters, drainage features and storm drain inletsInside the sediment basinOn a steep slope

Question 54 How should paints, solvents and fertilizers be stored?

Uncovered in the open so they're easy to findUnder cover or in sheds, in closed, labeled containers with secondary containment for liquidsIn the dumpsterNext to the construction exit

Question 55 A hydraulic hose bursts and sprays oil on the ground. What should happen first?

Wait for rain to wash it awayHose it into the ditchStop the leak and contain and clean up the spill immediately, then report it as requiredCover it with dirt and forget it

Question 56 Where should portable toilets be placed?

Directly over a storm drain inletAway from inlets and drainage features, on level ground, secured against tippingOn the edge of a streamInside the washout pit

Question 57 How does the EPA CGP define dewatering?

Draining accumulated stormwater or groundwater from foundations, vaults, trenches and similar points of accumulationWatering vegetation on finished slopesWashing equipmentFlushing fire hydrants

Question 58 What must dewatering water be routed through before discharge?

A storm drain inletA sediment control, such as a sediment basin or pumped-water filter bag, designed to prevent visual turbidityThe receiving streamNothing

Question 59 How often must a dewatering discharge be inspected under the EPA CGP?

WeeklyOnce per day on which the discharge occursMonthlyOnly after rain

Question 60 What is the turbidity benchmark for dewatering discharges under the 2022 CGP?

5 NTU50 NTU, based on the weekly average500 NTUThere is no benchmark

Question 61 Where must turbidity samples be collected?

Inside the excavation before pumpingAt each discharge point, after treatment and before the water leaves the site or enters a drainIn the receiving stream a mile downstreamAnywhere convenient

Question 62 The weekly average turbidity exceeds 50 NTU. What is the first step?

Wait for next week's averageImmediately take steps to minimize the discharge, including shutting off the dewatering discharge as soon as safely possibleAdd more water to dilute itStop sampling

Question 63 A dewatering discharge leaves a rainbow sheen on the water. What is needed?

Nothing if turbidity is lowAn oil-water separator or suitable filtration designed to remove oil and greaseA bigger pumpDischarging at night

Question 64 Where should a dewatering filter bag be placed?

On a steep slope so water drains fastDirectly in the streamOn a flat, stable, erosion-resistant surface, away from steep slopes, with velocity dissipation at the dischargeOn bare, loose soil

Question 65 Under the EPA CGP standard schedules, which is an acceptable inspection frequency?

Once a monthOnce every 14 calendar days and within 24 hours of a storm producing 0.25 inches or more of rainOnly after a complaintOnce every 30 days and after 1 inch of rain

Question 66 A site discharges to a sediment-impaired stream. What inspection frequency applies to that portion of the site?

Every 14 days onlyOnce every 7 calendar days and within 24 hours of a 0.25-inch stormMonthlyDaily

Question 67 How much snowfall triggers a snowmelt inspection under the 14-day schedule?

1 inch3.25 inches or more within a 24-hour period, once it melts and discharges12 inchesAny snow

Question 68 Within what time must an inspection report be completed under the EPA CGP?

7 days24 hours of completing the inspection30 daysAt the end of the project

Question 69 Which area must be inspected?

Only the main gateAll points of discharge from the siteThe site office break roomOnly areas that are already stabilized

Question 70 Areas of the site have completed stabilization. How may inspection frequency change there?

Twice in the first month, no more than 14 days apart, then once per monthNo more inspections are ever neededDaily inspections are requiredOnce a year

Question 71 If you inspect on the 14-day schedule, how do you show a storm triggered an inspection?

No documentation is neededRecord the rain gauge or representative weather station reading in the inspection reportTake a photo of the skyCall EPA

Question 72 A discharge is happening during the inspection. What must the inspector do?

Leave and return when it stopsIdentify the discharge points and observe and document the discharge's visual quality, such as color, odor, solids, foam and sheenCollect a lab sample for every pollutantNothing different

Question 73 A silt fence needs sediment removed but is otherwise intact. What is this?

Routine maintenanceA corrective action requiring a new controlA prohibited dischargeA water quality violation

Question 74 A section of silt fence was never installed where the SWPPP shows it. What does the CGP require?

Nothing until the next inspectionCorrective action, because a required control was never installedRemoving it from the SWPPPA new NOI

Question 75 A corrective action doesn't need a new control or significant repair. What is the deadline?

7 calendar daysBy the close of the next business day30 daysAt the end of the project

Question 76 A blown-out sediment basin outlet needs significant repair. What is the deadline?

Within 24 hoursNo later than 7 calendar days from discovery, or document why it's infeasible and the schedule30 calendar daysWhenever convenient

Question 77 When must a corrective action condition be entered in the log?

At the end of the monthWithin 24 hours of identifying the conditionWithin 7 daysOnly if EPA asks

Question 78 Under the EPA CGP, when must stabilization be initiated on an area that will be inactive for 14 or more days?

Within 14 daysImmediately, no later than the end of the next business dayWithin 30 daysAt project completion

Question 79 A site has 8 acres disturbed at once. How long does it have to complete stabilization after initiating it?

14 calendar days7 calendar days30 calendar days3 days

Question 80 What vegetative cover meets final stabilization under the EPA CGP?

30% of any vegetation50% of native coverUniform, perennial vegetation providing 70% or more of the cover native to local undisturbed areas100% sod everywhere

Question 81 How does adding impervious surface typically change runoff?

It increases runoff volume and peak flowIt reduces runoff volumeIt has no effectIt only changes water temperature

Question 82 What is the main purpose of a dry detention pond?

Store a permanent pool for wildlifeTemporarily store runoff and release it slowly to reduce peak flowInfiltrate all runoffTreat sewage

Question 83 What distinguishes a retention (wet) pond from a detention pond?

It's always smallerIt maintains a permanent pool of waterIt never dischargesIt's always underground

Question 84 Which practice primarily reduces runoff volume?

A dry detention pondAn infiltration basin or bioretention cellA curb inletA storm sewer pipe

Question 85 What is low impact development (LID)?

Building only small housesManaging rainfall close to where it falls with practices that mimic natural hydrologyAvoiding stormwater permitsUsing larger pipes

Question 86 Which MS4 control measure addresses permanent stormwater management for new development?

Public educationPost-construction stormwater management in new development and redevelopmentIllicit discharge detectionGood housekeeping for municipal operations

Question 87 What is the most common reason permanent stormwater practices fail?

Too much rain every yearLack of maintenance, such as clogged outlets and sediment-filled pondsToo many inspectionsThey're always undersized

Question 88 Which practice uses a stone reservoir under a surface that lets water pass through?

Green roofPermeable pavementHydrodynamic separatorRetention pond

Question 89 What does MS4 stand for?

Municipal separate storm sewer systemMain sanitary sewer system 4Multi-state stormwater standardMunicipal stormwater study series

Question 90 How many minimum control measures do small MS4 permits require?

ThreeFourSixTen

Question 91 Which is one of the six minimum control measures?

Free trash pickupIllicit discharge detection and eliminationWater rate settingBuilding code enforcement for electrical work

Question 92 The construction site runoff control measure applies to sites disturbing at least how much land?

10 acres5 acres1 acreAny amount

Question 93 Which permit does EPA issue for industrial stormwater where it's the permitting authority?

The Construction General PermitThe Multi-Sector General Permit (MSGP)An MS4 permitA building permit

Question 94 What is a no exposure certification?

A permit for constructionAn exclusion for industrial facilities whose materials and activities aren't exposed to stormwaterA certificate for inspectorsA waiver for rainfall erosivity

Question 95 Which routine requirement is common under industrial stormwater permits?

Daily NOI submissionQuarterly visual assessments of stormwater dischargesHourly lab samplingNo inspections

Question 96 Why do cities review construction erosion control plans?

They don'tBecause the MS4 construction runoff control measure requires an ordinance, plan review, inspections and enforcementOnly for tax purposesBecause OSHA requires it

Last reviewed: October 25, 2026 · Free general education based on the Clean Water Act, EPA NPDES rules and the EPA Construction General Permit. Your governing permit (EPA, state, tribal or local) controls. This is not legal advice, not EPA-approved, and not a California QSP/QSD or other state credential, and it does not issue a certificate. Nothing you enter on this page is saved or sent.

Stormwater and SWPPP Practice Test

Stormwater practice test: 20 random questions

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