DYNEGY MIDWEST GENERATION LLC — NPDES permit IL0004057: limits, due date and EPA's record

NPDES permit IL0004057 · Minor NON-POTW · effective, expires 2028-11-30 · EPA's file as of 2026-09-19

EPA's record, 2025-09-01 to 2026-08-31

Last period with anything received: 2026-07-31. Most often over: Solids, total suspended (1).

Reporting

Reports are due about 25 days after each monitoring period ends (the most common figure among IL permits in EPA's filings — check your permit).

Limits in force (138)

Outfall	Parameter	Statistic	Limit	Months
001	pH	MO MIN	>= 6 SU	all year
001	pH	MO MAX	<= 9 SU	all year
001	Solids, total suspended	30DA AVG	<= 15 mg/L	all year
001	Solids, total suspended	DAILY MX	<= 30 mg/L	all year
001	Nitrogen, ammonia total [as N]	30DA AVG	<= 1.5 mg/L	Mar, Apr, May, Sep, Oct
001	Nitrogen, ammonia total [as N]	30DA AVG	<= .9 mg/L	Jun, Jul, Aug
001	Nitrogen, ammonia total [as N]	30DA AVG	<= 2.7 mg/L	Jan, Feb, Nov, Dec
001	Nitrogen, ammonia total [as N]	DAILY MX	<= 5 mg/L	Mar, Apr, May, Sep, Oct
001	Nitrogen, ammonia total [as N]	DAILY MX	<= 4.8 mg/L	Jun, Jul, Aug
001	Nitrogen, ammonia total [as N]	DAILY MX	<= 4.2 mg/L	Jan, Feb, Nov, Dec
001	Cyanide, total [as CN]	DAILY MX	report only	all year
001	Cyanide, total [as CN]	DAILY MX	report only	all year
001	Cyanide, free [amenable to chlorination]	DAILY MX	report only	all year
001	Cyanide, free [amenable to chlorination]	DAILY MX	report only	all year
001	Chloride [as Cl]	DAILY MX	report only	all year
001	Chloride [as Cl]	DAILY MX	report only	all year
001	Sulfate, total [as SO4]	DAILY MX	report only	all year
001	Sulfate, total [as SO4]	DAILY MX	report only	all year
001	Fluoride, total [as F]	DAILY MX	report only	all year
001	Fluoride, total [as F]	DAILY MX	report only	all year
001	Arsenic, total [as As]	30DA AVG	<= .19 mg/L	all year
001	Arsenic, total [as As]	DAILY MX	<= .36 mg/L	all year
001	Barium, total [as Ba]	DAILY MX	report only	all year
001	Barium, total [as Ba]	DAILY MX	report only	all year
001	Boron, total [as B]	30DA AVG	<= 7.6 mg/L	all year
001	Boron, total [as B]	DAILY MX	<= 40.1 mg/L	all year
001	Cadmium, total [as Cd]	DAILY MX	report only	all year
001	Cadmium, total [as Cd]	DAILY MX	report only	all year
001	Chromium, total [as Cr]	DAILY MX	report only	all year
001	Chromium, total [as Cr]	DAILY MX	report only	all year
001	Copper, total [as Cu]	DAILY MX	report only	all year
001	Copper, total [as Cu]	DAILY MX	report only	all year
001	Iron, total [as Fe]	30DA AVG	<= 2 mg/L	all year
001	Iron, total [as Fe]	DAILY MX	<= 4 mg/L	all year
001	Iron, dissolved [as Fe]	DAILY MX	report only	all year
001	Iron, dissolved [as Fe]	DAILY MX	report only	all year
001	Lead, total [as Pb]	DAILY MX	report only	all year
001	Lead, total [as Pb]	DAILY MX	report only	all year
001	Manganese, total [as Mn]	DAILY MX	report only	all year
001	Manganese, total [as Mn]	DAILY MX	report only	all year
001	Thallium, total [as Tl]	DAILY MX	report only	all year
001	Thallium, total [as Tl]	DAILY MX	report only	all year
001	Nickel, total [as Ni]	DAILY MX	report only	all year
001	Nickel, total [as Ni]	DAILY MX	report only	all year
001	Silver, total [as Ag]	DAILY MX	report only	all year
001	Silver, total [as Ag]	DAILY MX	report only	all year
001	Zinc, total [as Zn]	DAILY MX	report only	all year
001	Zinc, total [as Zn]	DAILY MX	report only	all year
001	Antimony, total [as Sb]	DAILY MX	report only	all year
001	Antimony, total [as Sb]	DAILY MX	report only	all year
001	Selenium, total [as Se]	DAILY MX	report only	all year
001	Selenium, total [as Se]	DAILY MX	report only	all year
001	Oil and grease	30DA AVG	<= 15 mg/L	all year
001	Oil and grease	DAILY MX	<= 20 mg/L	all year
001	Radium 226, total	DAILY MX	report only	all year
001	Radium 226, total	DAILY MX	report only	all year
001	Radium 228, total	DAILY MX	report only	all year
001	Radium 228, total	DAILY MX	report only	all year
001	Phenolics, total recoverable	DAILY MX	report only	all year
001	Phenolics, total recoverable	DAILY MX	report only	all year
001	Flow, in conduit or thru treatment plant	MO AVG	report only	all year
001	Flow, in conduit or thru treatment plant	DAILY MX	report only	all year
001	Sulfates, total [as SO4]	DAILY MX	<= 2000 mg/L	all year
001	Mercury, total [as Hg]	ANNL AVG	<= 12 ng/L	all year
002	pH	MO MIN	>= 6 SU	all year
002	pH	MO MAX	<= 9 SU	all year
002	Solids, total suspended	30DA AVG	<= 15 mg/L	all year
002	Solids, total suspended	DAILY MX	<= 30 mg/L	all year
002	Oil and grease	30DA AVG	<= 15 mg/L	all year
002	Oil and grease	DAILY MX	<= 20 mg/L	all year
002	Flow, in conduit or thru treatment plant	MO AVG	report only	all year
002	Flow, in conduit or thru treatment plant	DAILY MX	report only	all year
003	pH	MO MIN	>= 6 SU	all year
003	pH	MO MAX	<= 9 SU	all year
003	Solids, total suspended	30DA AVG	<= 15 mg/L	all year
003	Solids, total suspended	DAILY MX	<= 30 mg/L	all year
003	Nitrogen, ammonia total [as N]	30DA AVG	<= 1.5 mg/L	Mar, Apr, May, Sep, Oct
003	Nitrogen, ammonia total [as N]	30DA AVG	<= .9 mg/L	Jun, Jul, Aug
003	Nitrogen, ammonia total [as N]	30DA AVG	<= 2.7 mg/L	Jan, Feb, Nov, Dec
003	Nitrogen, ammonia total [as N]	DAILY MX	<= 5 mg/L	Mar, Apr, May, Sep, Oct
003	Nitrogen, ammonia total [as N]	DAILY MX	<= 4.8 mg/L	Jun, Jul, Aug
003	Nitrogen, ammonia total [as N]	DAILY MX	<= 4.2 mg/L	Jan, Feb, Nov, Dec
003	Cyanide, total [as CN]	DAILY MX	report only	all year
003	Cyanide, total [as CN]	DAILY MX	report only	all year
003	Cyanide, free [amenable to chlorination]	DAILY MX	report only	all year
003	Cyanide, free [amenable to chlorination]	DAILY MX	report only	all year
003	Chloride [as Cl]	DAILY MX	report only	all year
003	Chloride [as Cl]	DAILY MX	report only	all year
003	Sulfate, total [as SO4]	DAILY MX	report only	all year
003	Sulfate, total [as SO4]	DAILY MX	report only	all year
003	Fluoride, total [as F]	DAILY MX	report only	all year
003	Fluoride, total [as F]	DAILY MX	report only	all year
003	Arsenic, total [as As]	30DA AVG	<= .19 mg/L	all year
003	Arsenic, total [as As]	DAILY MX	<= .36 mg/L	all year
003	Barium, total [as Ba]	DAILY MX	report only	all year
003	Barium, total [as Ba]	DAILY MX	report only	all year
003	Boron, total [as B]	30DA AVG	<= 7.6 mg/L	all year
003	Boron, total [as B]	DAILY MX	<= 40.1 mg/L	all year
003	Boron, total [as B]	DAILY MX	report only	all year
003	Boron, total [as B]	DAILY MX	report only	all year
003	Cadmium, total [as Cd]	DAILY MX	report only	all year
003	Cadmium, total [as Cd]	DAILY MX	report only	all year
003	Chromium, total [as Cr]	DAILY MX	report only	all year
003	Chromium, total [as Cr]	DAILY MX	report only	all year
003	Copper, total [as Cu]	DAILY MX	report only	all year
003	Copper, total [as Cu]	DAILY MX	report only	all year
003	Iron, total [as Fe]	30DA AVG	<= 2 mg/L	all year
003	Iron, total [as Fe]	DAILY MX	<= 4 mg/L	all year
003	Iron, dissolved [as Fe]	DAILY MX	report only	all year
003	Iron, dissolved [as Fe]	DAILY MX	report only	all year
003	Lead, total [as Pb]	DAILY MX	report only	all year
003	Lead, total [as Pb]	DAILY MX	report only	all year
003	Manganese, total [as Mn]	DAILY MX	report only	all year
003	Manganese, total [as Mn]	DAILY MX	report only	all year
003	Thallium, total [as Tl]	DAILY MX	report only	all year
003	Thallium, total [as Tl]	DAILY MX	report only	all year
003	Nickel, total [as Ni]	DAILY MX	report only	all year
003	Nickel, total [as Ni]	DAILY MX	report only	all year
003	Silver, total [as Ag]	DAILY MX	report only	all year
003	Silver, total [as Ag]	DAILY MX	report only	all year
003	Zinc, total [as Zn]	DAILY MX	report only	all year
003	Zinc, total [as Zn]	DAILY MX	report only	all year
003	Antimony, total [as Sb]	DAILY MX	report only	all year
003	Antimony, total [as Sb]	DAILY MX	report only	all year
003	Selenium, total [as Se]	DAILY MX	report only	all year
003	Selenium, total [as Se]	DAILY MX	report only	all year
003	Oil and grease	30DA AVG	<= 15 mg/L	all year
003	Oil and grease	DAILY MX	<= 20 mg/L	all year
003	Radium 226, total	DAILY MX	report only	all year
003	Radium 226, total	DAILY MX	report only	all year
003	Radium 228, total	DAILY MX	report only	all year
003	Radium 228, total	DAILY MX	report only	all year
003	Phenolics, total recoverable	DAILY MX	report only	all year
003	Phenolics, total recoverable	DAILY MX	report only	all year
003	Flow, in conduit or thru treatment plant	MO AVG	report only	all year
003	Flow, in conduit or thru treatment plant	DAILY MX	report only	all year
003	Sulfates, total [as SO4]	DAILY MX	<= 2000 mg/L	all year
003	Mercury, total [as Hg]	ANNL AVG	<= 12 ng/L	all year