NPDES LATEST 2026 EXAM QUESTIONS AND ANSWERS
GUARANTEE A+
✔✔Tertiary treatment - ✔✔Advanced polishing methods for wastewater treatment,
including filtration and UV treatment.
✔✔Design standards - ✔✔Standards that allow firms to choose their methods for
meeting technology-based numeric limits.
✔✔Discharge monitoring reports (DMRs) - ✔✔Public records that support agency and
citizen-suit enforcement related to wastewater discharge.
✔✔State revolving loan funds - ✔✔Funds that replaced grants for wastewater
treatment, leading to mixed incentives and history.
✔✔BAT - ✔✔Best Available Technology, economically achievable; consider costs, but
no formal cost-benefit balancing.
✔✔Nonconventional - ✔✔Generally BAT, with potential waivers/modifications; floor =
BPT (Best Practicable Technology, cost-benefit balancing allowed).
✔✔New sources - ✔✔NSPS using BADCT (best available control tech/processes/ops;
no explicit cost role). Rationale: no retrofit costs; politics favors higher new-source
stringency.
✔✔Effluent guidelines - ✔✔Industry-wide guidelines (≈60 categories) approved by
SCOTUS (1977) for administrability; challenges must target the guideline rulemaking,
not individual permits.
✔✔FDF - ✔✔Fundamentally Different Factors: site-specific physical/chemical/technical
differences make the national guideline inapplicable. Cost alone not enough.
✔✔BCT variances - ✔✔Limited variances based on economic capability or water-quality
adequacy.
✔✔Categorical pretreatment - ✔✔BAT-like for toxics unless POTW proves adequate
removal; POTWs often add local limits.
✔✔Groundwater to surface water - ✔✔Discharge to groundwater can need NPDES if
it's the 'functional equivalent' of a direct discharge to navigable water.
✔✔Factors for NPDES - ✔✔Non-exclusive factors include distance, transit time,
subsurface medium, dilution/chemical change, amount of pollutant reaching surface
water, manner of entry, etc.
, ✔✔Section 208 - ✔✔Required areawide management plans for waters with substantial
problems; no federal mandate to implement; no EPA backstop → largely toothless.
✔✔Section 319 - ✔✔Requires state NPS management programs, identification of
categories, BMPs 'earliest practicable', and plans.
✔✔CWA - ✔✔Excels at pipes; struggles with fields & asphalt.
✔✔Point source - ✔✔EPA (1973) tried to exempt some agriculture, feedlots, silviculture
from NPDES due to feasibility/admin burden.
✔✔NRDC v. Costle - ✔✔EPA cannot create categorical exemptions from statutory
definition; could use general permits/practice standards instead.
✔✔Return flows - ✔✔Congress responded: Excludes return flows from irrigated
agriculture from 'point source'; EPA cannot require permits for 'discharges composed
entirely of return flow from irrigated agriculture.'
✔✔Stormwater - ✔✔NPDES required for MS4s (municipal separate storm sewers) and
industrial stormwater.
✔✔Addition of a pollutant - ✔✔Dams: generally not 'adding' pollutants; courts wary of
intruding on state water allocation (Section 101(g) - Wallop Amendment).
✔✔Water transfers - ✔✔Transfer of turbid/warm water into clearer/colder creek required
NPDES (Catskills 2d Cir. 2001).
✔✔EPA 2008 Water Transfers Rule - ✔✔Transfers between navigable waters don't
require NPDES if no intervening industrial/municipal/commercial use.
✔✔Section 303 framework - ✔✔Designated uses for each water body (e.g., public
supply, fish/wildlife propagation, recreation).
✔✔Water quality criteria/standards - ✔✔Quantitative; toxics must be numeric. EPA
publishes criteria guidance; states adopt; EPA can promulgate if states fail.
✔✔Impaired waters list - ✔✔A total maximum daily load per pollutant that will still attain
standards (+ seasonal variation + margin of safety). Must allocate loads to point &
nonpoint sources and describe how to achieve.
✔✔Constructive submissions doctrine - ✔✔A legal principle from the 1980s-90s related
to courts forcing action.
GUARANTEE A+
✔✔Tertiary treatment - ✔✔Advanced polishing methods for wastewater treatment,
including filtration and UV treatment.
✔✔Design standards - ✔✔Standards that allow firms to choose their methods for
meeting technology-based numeric limits.
✔✔Discharge monitoring reports (DMRs) - ✔✔Public records that support agency and
citizen-suit enforcement related to wastewater discharge.
✔✔State revolving loan funds - ✔✔Funds that replaced grants for wastewater
treatment, leading to mixed incentives and history.
✔✔BAT - ✔✔Best Available Technology, economically achievable; consider costs, but
no formal cost-benefit balancing.
✔✔Nonconventional - ✔✔Generally BAT, with potential waivers/modifications; floor =
BPT (Best Practicable Technology, cost-benefit balancing allowed).
✔✔New sources - ✔✔NSPS using BADCT (best available control tech/processes/ops;
no explicit cost role). Rationale: no retrofit costs; politics favors higher new-source
stringency.
✔✔Effluent guidelines - ✔✔Industry-wide guidelines (≈60 categories) approved by
SCOTUS (1977) for administrability; challenges must target the guideline rulemaking,
not individual permits.
✔✔FDF - ✔✔Fundamentally Different Factors: site-specific physical/chemical/technical
differences make the national guideline inapplicable. Cost alone not enough.
✔✔BCT variances - ✔✔Limited variances based on economic capability or water-quality
adequacy.
✔✔Categorical pretreatment - ✔✔BAT-like for toxics unless POTW proves adequate
removal; POTWs often add local limits.
✔✔Groundwater to surface water - ✔✔Discharge to groundwater can need NPDES if
it's the 'functional equivalent' of a direct discharge to navigable water.
✔✔Factors for NPDES - ✔✔Non-exclusive factors include distance, transit time,
subsurface medium, dilution/chemical change, amount of pollutant reaching surface
water, manner of entry, etc.
, ✔✔Section 208 - ✔✔Required areawide management plans for waters with substantial
problems; no federal mandate to implement; no EPA backstop → largely toothless.
✔✔Section 319 - ✔✔Requires state NPS management programs, identification of
categories, BMPs 'earliest practicable', and plans.
✔✔CWA - ✔✔Excels at pipes; struggles with fields & asphalt.
✔✔Point source - ✔✔EPA (1973) tried to exempt some agriculture, feedlots, silviculture
from NPDES due to feasibility/admin burden.
✔✔NRDC v. Costle - ✔✔EPA cannot create categorical exemptions from statutory
definition; could use general permits/practice standards instead.
✔✔Return flows - ✔✔Congress responded: Excludes return flows from irrigated
agriculture from 'point source'; EPA cannot require permits for 'discharges composed
entirely of return flow from irrigated agriculture.'
✔✔Stormwater - ✔✔NPDES required for MS4s (municipal separate storm sewers) and
industrial stormwater.
✔✔Addition of a pollutant - ✔✔Dams: generally not 'adding' pollutants; courts wary of
intruding on state water allocation (Section 101(g) - Wallop Amendment).
✔✔Water transfers - ✔✔Transfer of turbid/warm water into clearer/colder creek required
NPDES (Catskills 2d Cir. 2001).
✔✔EPA 2008 Water Transfers Rule - ✔✔Transfers between navigable waters don't
require NPDES if no intervening industrial/municipal/commercial use.
✔✔Section 303 framework - ✔✔Designated uses for each water body (e.g., public
supply, fish/wildlife propagation, recreation).
✔✔Water quality criteria/standards - ✔✔Quantitative; toxics must be numeric. EPA
publishes criteria guidance; states adopt; EPA can promulgate if states fail.
✔✔Impaired waters list - ✔✔A total maximum daily load per pollutant that will still attain
standards (+ seasonal variation + margin of safety). Must allocate loads to point &
nonpoint sources and describe how to achieve.
✔✔Constructive submissions doctrine - ✔✔A legal principle from the 1980s-90s related
to courts forcing action.
