Clean Water Act discharge permit · NPDES COG591221

SILVER CLIFF RANCH, Nathrop (Historical), CO: NPDES COG591221 discharge permit, effluent exceedances, inspections, penalties

EffectivePermit status
MinorDischarger class
80Pollutants under a numeric limit
1Pollutants with an effluent exceedance

SILVER CLIFF RANCH, held by Silver Cliff Ranch, holds NPDES permit COG591221, which discharges to Chalk Creek. EPA’s file records it issued December 23, 2024 and expiring December 31, 2031. The status and dates are as EPA’s permit file stood when Velarion loaded it (October 14, 2026); EPA’s free Detailed Facility Report on ECHO carries the permit’s current standing.

Identity

Facility as filed	SILVER CLIFF RANCH
Permittee as filed	Silver Cliff Ranch
NPDES ID	COG591221
Permit status	Effective
Permit type	Coverage under a general permit
Discharger class	Minor discharger
Facility type	Not a publicly owned treatment works
Issued	December 23, 2024
Expiration date	December 31, 2031
Address	Nathrop (Historical), CO 81236
Receiving water	Chalk Creek
Receiving water impaired	303(D) Listed
Subwatershed	Outlet Chalk Creek (HUC 110200010502)
SIC	4952 – Sewerage Systems

Cited to the EPA ICIS-NPDES permit file (ECHO download) and EPA’s NAICS/SIC and component files, the same download.

Effluent limits and exceedances

80Pollutants on file
80Under a numeric limit
30With a violation of any kind
1With 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 80 are shown.

Pollutant or measure	Limits	Violations, any kind	Effluent exceedances	Latest exceedance	Largest exceedance, as filed
Nitrogen, inorganic total	2	2	2	July 31, 2026	77% over the limit
Zinc, potentially dissolved	4	5	0
Lead, potentially dissolvd	3	5	0
BOD, 5-day, 20 deg. C	6	4	0
Cadmium, potentially dissolvd	3	4	0
Solids, total suspended	4	2	0
Flow, in conduit or thru treatment plant	4	2	0
Plant capacity fact. percent of capacity	2	2	0
Chromium, hexavalent dissolved [as Cr]	2	2	0
Silver, potentially dissolved	2	2	0
Copper, potentially dissolved	2	2	0
Manganese, potentially dissolvd	2	2	0
Nickel, potentially dissolvd	2	2	0
Selenium, potentially dissolvd	2	2	0
Uranium, potentially dissolvd	2	2	0
Sulfide-hydrogen sulfide [undissociated]	2	2	0
Arsenic, total recoverable	1	2	0
Nitrogen, nitrite total [as N]	1	1	0
Iron, total recoverable	1	1	0
Iron, dissolved [as Fe]	1	1	0
Manganese, dissolved [as Mn]	1	1	0
Nickel, total recoverable	1	1	0
Cadmium, total recoverable	1	1	0
Lead, total recoverable	1	1	0
Molybdenum, total recoverable	1	1	0
Arsenic, potentially dissolved	1	1	0
Chromium, trivalent, potentially dissolvd	1	1	0
Chromium, trivalent total recoverable	1	1	0
Mercury, total [low level]	1	1	0
Sulfate	1	1	0
Nitrogen, ammonia total [as N]	38	0	0
pH	2	0	0
Chloride [as Cl]	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

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 COG591221.

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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EPA publishes a free Detailed Facility Report for every permit on ECHO: its compliance status quarter by quarter, its inspections, and its enforcement actions and penalties. EPA also sends free notices of new inspections and enforcement actions through ECHO Notify; enter NPDES ID COG591221 there.

Nearby on the register

Figures from EPA’s ICIS-NPDES download, loaded October 14, 2026.

This public-records page covers Clean Water Act discharge permit NPDES COG591221 for SILVER CLIFF RANCH in Nathrop (Historical), CO, held by Silver Cliff Ranch, which discharges to Chalk Creek in the Chalk Creek watershed (HUC 110200010502). The permit is listed as Effective, was issued December 23, 2024, and expires December 31, 2031, with 80 pollutants on file, 80 under a numeric limit, and 30 with a violation.