Clean Water Act discharge permit · NPDES COG591186

NIWOT SANITATION DISTRICT WWTF, Longmont, CO: NPDES COG591186 discharge permit, effluent exceedances, inspections, penalties

EffectivePermit status
MinorDischarger class
69Pollutants under a numeric limit
2Pollutants with an effluent exceedance

NIWOT SANITATION DISTRICT WWTF, held by Niwot Sanitation District, holds NPDES permit COG591186, which discharges to Dry Creek. EPA’s file records it issued March 1, 2023 and expiring May 31, 2027. The status and dates are as EPA’s permit file stood when Velarion loaded it (September 15, 2026); EPA’s free Detailed Facility Report on ECHO carries the permit’s current standing.

Identity

Facility as filed	NIWOT SANITATION DISTRICT WWTF
Permittee as filed	Niwot Sanitation District
NPDES ID	COG591186
Permit status	Effective
Permit type	Coverage under a general permit
Discharger class	Minor discharger
Facility type	Not a publicly owned treatment works
Issued	March 1, 2023
Expiration date	May 31, 2027
Address	Longmont, CO 80504
Receiving water	Dry Creek
Subwatershed	Boulder Reservoir (HUC 101900050704)

Cited to the EPA ICIS-NPDES permit file (ECHO download).

Effluent limits and exceedances

69Pollutants on file
69Under a numeric limit
2With a violation of any kind
2With an effluent exceedance

An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant; the 60 with the most exceedances of 69 are shown.

Pollutant or measure	Limits	Violations, any kind	Effluent exceedances	Latest exceedance	Largest exceedance, as filed
Nitrogen, inorganic total	1	4	4	April 30, 2026	123% over the limit
Static Renewal 7 Day Chronic Ceriodaphnia dubia	3	1	1	June 30, 2026	40% over the limit
Nitrogen, ammonia total [as N]	24	0	0
BOD, 5-day, 20 deg. C	6	0	0
Solids, total suspended	4	0	0
Flow, in conduit or thru treatment plant	4	0	0
Static Renewal 7 Day Chronic Pimephales promelas	3	0	0
Plant capacity fact. percent of capacity	2	0	0
pH	2	0	0
Chlorine, total residual	2	0	0
E. coli	2	0	0
Perfluorooctanoic acid (PFOA)	2	0	0
Perfluorobutanoic acid (PFBA)	2	0	0
Perfluorooctanesulfonamide (PFOSA)	2	0	0
Perfluoropentanoic acid (PFPeA)	2	0	0
Perfluorohexanoic acid (PFHxA)	2	0	0
Perfluoroheptanoic acid (PFHpA)	2	0	0
Perfluorononanoic acid (PFNA)	2	0	0
Perfluorodecanoic acid (PFDA)	2	0	0
Perfluoroundecanoic acid (PFUnA)	2	0	0
Perfluorododecanoic acid (PFDoA)	2	0	0
Perfluorotridecanoic acid (PFTrDA)	2	0	0
Perfluorotetradecanoic acid (PFTeDA)	2	0	0
N-ethyl perfluorooctanesulfonamidoethanol (NEtFOSE)	2	0	0
N-methyl perfluorooctanesulfonamidoethanol (NMeFOSE)	2	0	0
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)	2	0	0
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)	2	0	0
Perfluorobutanesulfonic acid (PFBS)	2	0	0
Perfluorodecanesulfonic acid (PFDS)	2	0	0
Perfluoroheptanesulfonic acid (PFHpS)	2	0	0
Perfluorohexanesulfonic acid (PFHxS)	2	0	0
Perfluorooctanesulfonic acid (PFOS)	2	0	0
1H,1H,2H,2H-Perfluorohexane sulfonic acid (4:2 FTS)	2	0	0
1H,1H,2H,2H-Perfluorooctane sulfonic acid (6:2 FTS)	2	0	0
1H,1H, 2H, 2H-Perfluorodecane sulfonic acid (8:2 FTS)	2	0	0
Perfluoropentanesulfonic acid (PFPeS)	2	0	0
Perfluorononanesulfonic acid (PFNS)	2	0	0
Hexafluoropropylene oxide dimer acid (HFPO-DA)	2	0	0
Perfluoro-2-methoxypropanoic acid	2	0	0
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)	2	0	0
Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA)	2	0	0
Perfluorododecanesulfonic acid (PFDoS)	2	0	0
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)	2	0	0
Potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate	2	0	0
Potassium 11-chloroeicosafluoro-3-oxaundecane-1-sulfonate	2	0	0
N-methyl perfluorooctanesulfonamide (NMeFOSA)	2	0	0
N-ethyl perfluorooctanesulfonamide (NEtFOSA)	2	0	0
PFAS Sum	2	0	0
3-Perfluoropropyl propanoic acid (3:3 FTCA)	2	0	0
3-Perfluoroheptyl propanoic acid (7:3 FTCA)	2	0	0
Perfluoro-4-methoxybutanoic acid (PFMBA)	2	0	0
2H,2H,3H,3H-Perfluorooctanoic acid (5:3 FTCA)	2	0	0
Cyanide, total [as CN]	1	0	0
Arsenic, total [as As]	1	0	0
Cadmium, total [as Cd]	1	0	0
Chromium, total [as Cr]	1	0	0
Copper, total [as Cu]	1	0	0
Lead, total [as Pb]	1	0	0
Molybdenum, total [as Mo]	1	0	0
Nickel, total [as Ni]	1	0	0

Cited to the EPA ICIS-NPDES limits and effluent violations files (ECHO download); up to 60 rows shown, most exceedances first.

Inspections, violations and enforcement

0Single-event violations

EPA’s single-event violation file, as loaded, holds no violation for NPDES COG591186.

Velarion’s copy of EPA’s ICIS-NPDES files does not include the inspections, formal enforcement actions and informal enforcement actions files, so this page shows none of them. EPA’s free Detailed Facility Report on ECHO lists this permit’s inspections, enforcement actions and penalties.

Cited to the EPA ICIS-NPDES violation, inspection and enforcement files (ECHO download); up to 50 rows of each shown, newest first.

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Nearby on the register

Figures from EPA’s ICIS-NPDES download, loaded September 15, 2026.

This public-records page covers the Clean Water Act discharge permit NPDES COG591186 for the NIWOT SANITATION DISTRICT WWTF in Longmont, CO, held by Niwot Sanitation District and discharging to Dry Creek within the Boulder Reservoir subwatershed (HUC 101900050704). The page lists 69 pollutants on file, of which 69 are under a numeric limit, and 2 pollutants with an effluent exceedance.