Clean Water Act discharge permit · NPDES MO0129216

TWIN LAKES WWTF, Mercer, MO: NPDES MO0129216 discharge permit, effluent exceedances, inspections, penalties

Administratively continuedPermit status
MinorDischarger class
8Pollutants under a numeric limit
2Pollutants with an effluent exceedance

TWIN LAKES WWTF, held by Twin Lakes Association Inc., holds NPDES permit MO0129216, which discharges to Tributary To Hidden Valley Lake. EPA’s file records it issued January 4, 2019 and expiring September 30, 2023. 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	TWIN LAKES WWTF
Permittee as filed	Twin Lakes Association Inc.
NPDES ID	MO0129216
Permit status	Administratively continued (past its expiration date and still in force until reissued)
Permit type	Individual permit
Discharger class	Minor discharger
Facility type	Not a publicly owned treatment works
Issued	January 4, 2019
Expiration date	September 30, 2023
Address	Mercer, MO 64661
Receiving water	Tributary to Hidden Valley Lake
Subwatershed	Big Branch-Weldon River (HUC 102801020901)
SIC	8641 – Civic And Social Associations

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

12Pollutants on file
8Under a numeric limit
12With 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.

Pollutant or measure	Limits	Violations, any kind	Effluent exceedances	Latest exceedance	Largest exceedance, as filed
pH	2	43	2	January 31, 2024
Coliform, fecal general	0	4	2	June 30, 2010	328% over the limit
Nitrogen, ammonia total [as N]	4	46	0
Flow, in conduit or thru treatment plant	2	44	0
BOD, 5-day, 20 deg. C	2	42	0
Solids, total suspended	2	42	0
Phosphorus, total [as P]	2	26	0
Nitrogen, total [as N]	2	20	0
E. coli	2	16	0
Nitrogen, Kjeldahl, total [as N]	0	12	0
Nitrite + Nitrate total [as N]	0	12	0
E. coli, colony forming units [CFU]	0	2	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

4Single-event violations

Date	What EPA recorded	Agency
March 9, 2023	Reporting Violations - Improper/ Incorrect Reporting	ST6
June 30, 2020	Reporting Violations - Failure to Submit DMRs	ST6
June 30, 2020	Effluent Violations - Numeric effluent violation	ST6
July 9, 2019	Reporting Violations - Improper/ Incorrect Reporting	ST6

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 MO0129216 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 MO0129216 for TWIN LAKES WWTF in Mercer, MO, held by Twin Lakes Association Inc., which discharges to Tributary To Hidden Valley Lake within the Big Branch-Weldon River subwatershed (HUC 102801020901). The permit is listed as administratively continued, with a Minor discharger class, 2 pollutants under a numeric limit, and 2 pollutants with an effluent exceedance.