STILLWATER MINING COMPANY — NPDES permit MT0024716: limits, due date and EPA's record

NPDES permit MT0024716 · Minor NON-POTW · effective, expires 2028-08-31 · 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: Lead, total recoverable (3), Copper, total recoverable (3).

Reporting

Reports are due about 28 days after each monitoring period ends (read off this permit's own late-day counts in EPA's filings).

Limits in force (325)

Outfall	Parameter	Statistic	Limit	Months
001	Flow rate	MO AVG	report only	all year
001	Flow rate	DAILY MX	report only	all year
001	pH	MINIMUM	>= 6 SU	all year
001	pH	MAXIMUM	<= 9 SU	all year
001	Solids, total suspended	MO AVG	<= 20 mg/L	all year
001	Solids, total suspended	DAILY MX	<= 30 mg/L	all year
001	Oil & Grease	MO AVG	<= 10 mg/L	all year
001	Oil & Grease	DAILY MX	<= 10 mg/L	all year
001	Nitrogen, total [as N]	MO AVG	report only	all year
001	Nitrogen, total [as N]	DAILY MX	report only	all year
001	Nitrogen, total [as N]	MO AVG	report only	all year
001	Nitrogen, total [as N]	DAILY MX	report only	all year
001	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
001	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
001	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
001	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
001	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
001	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
001	Phosphorus, total [as P]	MO AVG	report only	all year
001	Phosphorus, total [as P]	DAILY MX	report only	all year
001	Nickel, total recoverable	MO AVG	report only	all year
001	Nickel, total recoverable	DAILY MX	report only	all year
001	Silver total recoverable	MO AVG	report only	all year
001	Silver total recoverable	DAILY MX	report only	all year
001	Zinc, total recoverable	MO AVG	<= 22.1 ug/L	all year
001	Zinc, total recoverable	DAILY MX	<= 37 ug/L	all year
001	Aluminum, dissolved [as Al]	MO AVG	report only	all year
001	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
001	Cadmium, total recoverable	MO AVG	<= .24 ug/L	all year
001	Cadmium, total recoverable	DAILY MX	<= .49 ug/L	all year
001	Lead, total recoverable	MO AVG	<= 3.05 ug/L	all year
001	Lead, total recoverable	DAILY MX	<= 4.04 ug/L	all year
001	Copper, total recoverable	MO AVG	<= 2.85 ug/L	all year
001	Copper, total recoverable	DAILY MX	<= 3.8 ug/L	all year
001	Mercury, total recoverable	MO AVG	<= .49 ug/L	all year
001	Mercury, total recoverable	DAILY MX	<= .49 ug/L	all year
001	Pass/Fail Static 96 Hr Acute Pimephales Promelas	VALUE	<= 0 pass=0;fail=1	all year
001	Pass/Fail Static Renewal 48Hr Acute Ceriodaphnia dubia	VALUE	<= 0 pass=0;fail=1	all year
002	Flow rate	MO AVG	report only	all year
002	Flow rate	MO AVG	report only	all year
002	Flow rate	DAILY MX	report only	all year
002	Flow rate	DAILY MX	report only	all year
002	pH	MINIMUM	report only	all year
002	pH	MINIMUM	>= 6 SU	all year
002	pH	MAXIMUM	report only	all year
002	pH	MAXIMUM	<= 9 SU	all year
002	Nitrogen, total [as N]	MO AVG	report only	all year
002	Nitrogen, total [as N]	MO AVG	report only	all year
002	Nitrogen, total [as N]	DAILY MX	report only	all year
002	Nitrogen, total [as N]	DAILY MX	report only	all year
002	Nitrogen, total [as N]	MO AVG	report only	all year
002	Nitrogen, total [as N]	MO AVG	report only	all year
002	Nitrogen, total [as N]	DAILY MX	report only	all year
002	Nitrogen, total [as N]	DAILY MX	report only	all year
002	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
002	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
002	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
002	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
002	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
002	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
002	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
002	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
002	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
002	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
002	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
002	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
002	Phosphorus, total [as P]	MO AVG	report only	all year
002	Phosphorus, total [as P]	MO AVG	report only	all year
002	Phosphorus, total [as P]	DAILY MX	report only	all year
002	Phosphorus, total [as P]	DAILY MX	report only	all year
002	Nickel, total recoverable	MO AVG	report only	all year
002	Nickel, total recoverable	MO AVG	report only	all year
002	Nickel, total recoverable	DAILY MX	report only	all year
002	Nickel, total recoverable	DAILY MX	report only	all year
002	Silver total recoverable	MO AVG	report only	all year
002	Silver total recoverable	MO AVG	report only	all year
002	Silver total recoverable	DAILY MX	report only	all year
002	Silver total recoverable	DAILY MX	report only	all year
002	Zinc, total recoverable	MO AVG	<= 58 ug/L	all year
002	Zinc, total recoverable	MO AVG	report only	all year
002	Zinc, total recoverable	DAILY MX	<= 96 ug/L	all year
002	Zinc, total recoverable	DAILY MX	report only	all year
002	Aluminum, dissolved [as Al]	MO AVG	report only	all year
002	Aluminum, dissolved [as Al]	MO AVG	report only	all year
002	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
002	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
002	Cadmium, total recoverable	MO AVG	report only	all year
002	Cadmium, total recoverable	MO AVG	<= .4 ug/L	all year
002	Cadmium, total recoverable	DAILY MX	report only	all year
002	Cadmium, total recoverable	DAILY MX	<= .8 ug/L	all year
002	Lead, total recoverable	MO AVG	<= .74 ug/L	all year
002	Lead, total recoverable	MO AVG	report only	all year
002	Lead, total recoverable	DAILY MX	<= 1 ug/L	all year
002	Lead, total recoverable	DAILY MX	report only	all year
002	Copper, total recoverable	MO AVG	report only	all year
002	Copper, total recoverable	MO AVG	<= 4.4 ug/L	all year
002	Copper, total recoverable	DAILY MX	report only	all year
002	Copper, total recoverable	DAILY MX	<= 5.8 ug/L	all year
002	Mercury, total recoverable	MO AVG	report only	all year
002	Mercury, total recoverable	MO AVG	<= .1 ug/L	all year
002	Mercury, total recoverable	DAILY MX	report only	all year
002	Mercury, total recoverable	DAILY MX	<= .1 ug/L	all year
003	Flow rate	MO AVG	report only	all year
003	Flow rate	MO AVG	report only	all year
003	Flow rate	MO AVG	report only	all year
003	Flow rate	MO AVG	report only	all year
003	Flow rate	DAILY MX	report only	all year
003	Flow rate	DAILY MX	report only	all year
003	Flow rate	DAILY MX	report only	all year
003	Flow rate	DAILY MX	report only	all year
003	pH	MINIMUM	>= 6 SU	all year
003	pH	MINIMUM	report only	all year
003	pH	MINIMUM	>= 6 SU	all year
003	pH	MINIMUM	report only	all year
003	pH	MAXIMUM	<= 9 SU	all year
003	pH	MAXIMUM	report only	all year
003	pH	MAXIMUM	<= 9 SU	all year
003	pH	MAXIMUM	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	MO AVG	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, total [as N]	DAILY MX	report only	all year
003	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
003	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
003	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
003	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
003	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
003	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
003	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
003	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
003	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
003	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
003	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
003	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
003	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
003	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
003	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
003	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
003	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
003	Phosphorus, total [as P]	MO AVG	report only	all year
003	Phosphorus, total [as P]	MO AVG	report only	all year
003	Phosphorus, total [as P]	MO AVG	report only	all year
003	Phosphorus, total [as P]	MO AVG	report only	all year
003	Phosphorus, total [as P]	DAILY MX	report only	all year
003	Phosphorus, total [as P]	DAILY MX	report only	all year
003	Phosphorus, total [as P]	DAILY MX	report only	all year
003	Phosphorus, total [as P]	DAILY MX	report only	all year
003	Nickel, total recoverable	MO AVG	report only	all year
003	Nickel, total recoverable	MO AVG	report only	all year
003	Nickel, total recoverable	MO AVG	report only	all year
003	Nickel, total recoverable	MO AVG	report only	all year
003	Nickel, total recoverable	DAILY MX	report only	all year
003	Nickel, total recoverable	DAILY MX	report only	all year
003	Nickel, total recoverable	DAILY MX	report only	all year
003	Nickel, total recoverable	DAILY MX	report only	all year
003	Silver total recoverable	MO AVG	report only	all year
003	Silver total recoverable	MO AVG	report only	all year
003	Silver total recoverable	MO AVG	report only	all year
003	Silver total recoverable	MO AVG	report only	all year
003	Silver total recoverable	DAILY MX	report only	all year
003	Silver total recoverable	DAILY MX	report only	all year
003	Silver total recoverable	DAILY MX	report only	all year
003	Silver total recoverable	DAILY MX	report only	all year
003	Zinc, total recoverable	MO AVG	report only	all year
003	Zinc, total recoverable	MO AVG	<= 45 ug/L	all year
003	Zinc, total recoverable	MO AVG	report only	all year
003	Zinc, total recoverable	MO AVG	report only	all year
003	Zinc, total recoverable	DAILY MX	report only	all year
003	Zinc, total recoverable	DAILY MX	<= 76 ug/L	all year
003	Zinc, total recoverable	DAILY MX	report only	all year
003	Zinc, total recoverable	DAILY MX	report only	all year
003	Aluminum, dissolved [as Al]	MO AVG	report only	all year
003	Aluminum, dissolved [as Al]	MO AVG	report only	all year
003	Aluminum, dissolved [as Al]	MO AVG	report only	all year
003	Aluminum, dissolved [as Al]	MO AVG	report only	all year
003	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
003	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
003	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
003	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
003	Cadmium, total recoverable	MO AVG	report only	all year
003	Cadmium, total recoverable	MO AVG	<= .1 ug/L	all year
003	Cadmium, total recoverable	MO AVG	report only	all year
003	Cadmium, total recoverable	MO AVG	report only	all year
003	Cadmium, total recoverable	DAILY MX	report only	all year
003	Cadmium, total recoverable	DAILY MX	<= .2 ug/L	all year
003	Cadmium, total recoverable	DAILY MX	report only	all year
003	Cadmium, total recoverable	DAILY MX	report only	all year
003	Lead, total recoverable	MO AVG	<= .6 ug/L	all year
003	Lead, total recoverable	MO AVG	report only	all year
003	Lead, total recoverable	MO AVG	report only	all year
003	Lead, total recoverable	MO AVG	report only	all year
003	Lead, total recoverable	DAILY MX	<= .8 ug/L	all year
003	Lead, total recoverable	DAILY MX	report only	all year
003	Lead, total recoverable	DAILY MX	report only	all year
003	Lead, total recoverable	DAILY MX	report only	all year
003	Copper, total recoverable	MO AVG	report only	all year
003	Copper, total recoverable	MO AVG	<= 3.5 ug/L	all year
003	Copper, total recoverable	MO AVG	report only	all year
003	Copper, total recoverable	MO AVG	report only	all year
003	Copper, total recoverable	DAILY MX	report only	all year
003	Copper, total recoverable	DAILY MX	<= 4.7 ug/L	all year
003	Copper, total recoverable	DAILY MX	report only	all year
003	Copper, total recoverable	DAILY MX	report only	all year
003	Mercury, total recoverable	MO AVG	report only	all year
003	Mercury, total recoverable	MO AVG	report only	all year
003	Mercury, total recoverable	MO AVG	<= .1 ug/L	all year
003	Mercury, total recoverable	MO AVG	report only	all year
003	Mercury, total recoverable	DAILY MX	report only	all year
003	Mercury, total recoverable	DAILY MX	report only	all year
003	Mercury, total recoverable	DAILY MX	<= .1 ug/L	all year
003	Mercury, total recoverable	DAILY MX	report only	all year
RIV	pH	QRTR AVG	report only	all year
RIV	pH	QRTR AVG	report only	all year
RIV	Nitrogen, total [as N]	QRTR AVG	report only	Jul, Aug, Sep
RIV	Nitrogen, total [as N]	QRTR AVG	report only	Jul, Aug, Sep
RIV	Nitrogen, ammonia total [as N]	QRTR AVG	report only	all year
RIV	Nitrogen, ammonia total [as N]	QRTR AVG	report only	all year
RIV	Nitrogen, Kjeldahl, total [as N]	QRTR AVG	report only	all year
RIV	Nitrogen, Kjeldahl, total [as N]	QRTR AVG	report only	all year
RIV	Nitrite + Nitrate total [as N]	QRTR AVG	report only	all year
RIV	Nitrite + Nitrate total [as N]	QRTR AVG	report only	all year
RIV	Phosphorus, total [as P]	QRTR AVG	report only	all year
RIV	Phosphorus, total [as P]	QRTR AVG	report only	all year
RIV	Hardness, total [as CaCO3]	QRTR AVG	report only	all year
RIV	Hardness, total [as CaCO3]	QRTR AVG	report only	all year
RIV	Nickel, total recoverable	QRTR AVG	report only	all year
RIV	Nickel, total recoverable	QRTR AVG	report only	all year
RIV	Silver total recoverable	QRTR AVG	report only	all year
RIV	Silver total recoverable	QRTR AVG	report only	all year
RIV	Zinc, total recoverable	QRTR AVG	report only	all year
RIV	Zinc, total recoverable	QRTR AVG	report only	all year
RIV	Aluminum, dissolved [as Al]	QRTR AVG	report only	all year
RIV	Aluminum, dissolved [as Al]	QRTR AVG	report only	all year
RIV	Cadmium, total recoverable	QRTR AVG	report only	all year
RIV	Cadmium, total recoverable	QRTR AVG	report only	all year
RIV	Lead, total recoverable	QRTR AVG	report only	all year
RIV	Lead, total recoverable	QRTR AVG	report only	all year
RIV	Copper, total recoverable	QRTR AVG	report only	all year
RIV	Copper, total recoverable	QRTR AVG	report only	all year
RIV	Mercury, total recoverable	QRTR AVG	report only	all year
RIV	Mercury, total recoverable	QRTR AVG	report only	all year
SUM	Flow rate	MO AVG	report only	all year
SUM	Flow rate	MO AVG	report only	all year
SUM	Flow rate	DAILY MX	report only	all year
SUM	Flow rate	DAILY MX	report only	all year
SUM	pH	MINIMUM	>= 6 SU	all year
SUM	pH	MINIMUM	>= 6 SU	all year
SUM	pH	MAXIMUM	<= 9 SU	all year
SUM	pH	MAXIMUM	<= 9 SU	all year
SUM	Nitrogen, total [as N]	MO AVG	report only	all year
SUM	Nitrogen, total [as N]	MO AVG	report only	all year
SUM	Nitrogen, total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, total [as N]	MO AVG	report only	all year
SUM	Nitrogen, total [as N]	MO AVG	<= 60 lb/d	all year
SUM	Nitrogen, total [as N]	MO AVG	report only	all year
SUM	Nitrogen, total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
SUM	Nitrogen, ammonia total [as N]	MO AVG	report only	all year
SUM	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, ammonia total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
SUM	Nitrogen, Kjeldahl, total [as N]	MO AVG	report only	all year
SUM	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
SUM	Nitrogen, Kjeldahl, total [as N]	DAILY MX	report only	all year
SUM	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
SUM	Nitrite + Nitrate total [as N]	MO AVG	report only	all year
SUM	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
SUM	Nitrite + Nitrate total [as N]	DAILY MX	report only	all year
SUM	Phosphorus, total [as P]	MO AVG	report only	all year
SUM	Phosphorus, total [as P]	MO AVG	report only	all year
SUM	Phosphorus, total [as P]	DAILY MX	report only	all year
SUM	Phosphorus, total [as P]	DAILY MX	report only	all year
SUM	Nickel, total recoverable	MO AVG	report only	all year
SUM	Nickel, total recoverable	MO AVG	report only	all year
SUM	Nickel, total recoverable	DAILY MX	report only	all year
SUM	Nickel, total recoverable	DAILY MX	report only	all year
SUM	Silver total recoverable	MO AVG	report only	all year
SUM	Silver total recoverable	MO AVG	report only	all year
SUM	Silver total recoverable	DAILY MX	report only	all year
SUM	Silver total recoverable	DAILY MX	report only	all year
SUM	Zinc, total recoverable	MO AVG	<= 58 ug/L	all year
SUM	Zinc, total recoverable	MO AVG	<= 45 ug/L	all year
SUM	Zinc, total recoverable	DAILY MX	<= 96 ug/L	all year
SUM	Zinc, total recoverable	DAILY MX	<= 76 ug/L	all year
SUM	Aluminum, dissolved [as Al]	MO AVG	report only	all year
SUM	Aluminum, dissolved [as Al]	MO AVG	report only	all year
SUM	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
SUM	Aluminum, dissolved [as Al]	DAILY MX	report only	all year
SUM	Cadmium, total recoverable	MO AVG	<= .4 ug/L	all year
SUM	Cadmium, total recoverable	MO AVG	<= .1 ug/L	all year
SUM	Cadmium, total recoverable	DAILY MX	<= .8 ug/L	all year
SUM	Cadmium, total recoverable	DAILY MX	<= .2 ug/L	all year
SUM	Lead, total recoverable	MO AVG	<= .74 ug/L	all year
SUM	Lead, total recoverable	MO AVG	<= .6 ug/L	all year
SUM	Lead, total recoverable	DAILY MX	<= 1 ug/L	all year
SUM	Lead, total recoverable	DAILY MX	<= .8 ug/L	all year
SUM	Copper, total recoverable	MO AVG	<= 4.4 ug/L	all year
SUM	Copper, total recoverable	MO AVG	<= 3.5 ug/L	all year
SUM	Copper, total recoverable	DAILY MX	<= 5.8 ug/L	all year
SUM	Copper, total recoverable	DAILY MX	<= 4.7 ug/L	all year
SUM	Mercury, total recoverable	MO AVG	<= .1 ug/L	all year
SUM	Mercury, total recoverable	MO AVG	<= .1 ug/L	all year
SUM	Mercury, total recoverable	DAILY MX	<= .1 ug/L	all year
SUM	Mercury, total recoverable	DAILY MX	<= .1 ug/L	all year