INTERSTATE POWER AND LIGHT COMPANY

NPDES permit IA0001783 · Major NON-POTW · effective, expires 2030-12-31 · EPA's file as of 2026-09-19

Check this month's numbers before you file
Watch this permit — $79 a month. Every Monday, from EPA's newest files: the next report due and when, whether EPA's file holds your last one, any change to this permit's limits or status, and the renewal date.

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

0values over a limit
11required values missing, on 6 form(s)
0of 48 forms filed late

Last period with anything received: 2026-08-31.

Reporting

Reports are due about 15 days after each monitoring period ends (the most common figure among IA permits in EPA's filings — check your permit).

Limits in force (49)

OutfallParameterStatisticLimitMonths
001Toxicity [acute], Ceriodaphnia dubia30DA AVG <= 1 N=0;Y=1 all year
001Toxicity [acute], Pimephales promelas [Fathead Minnow]30DA AVG <= 1 N=0;Y=1 all year
002pHDAILY MN >= 6 SU all year
002pHDAILY MX <= 9 SU all year
002Solids, total suspended30DA AVG <= 30 mg/L all year
002Solids, total suspendedDAILY MX <= 45 mg/L all year
002Solids, total suspended30DA AVG <= .25 lb/d all year
002Solids, total suspendedDAILY MX <= .38 lb/d all year
002E. coliGEO MEAN <= 126 #/100mL Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov
002BOD, carbonaceous [5 day, 20 C]30DA AVG <= 25 mg/L all year
002BOD, carbonaceous [5 day, 20 C]DAILY MX <= 40 mg/L all year
002BOD, carbonaceous [5 day, 20 C]30DA AVG <= .21 lb/d all year
002BOD, carbonaceous [5 day, 20 C]DAILY MX <= .33 lb/d all year
004Temperature, water deg. fahrenheit30DA AVG <= 196.3 deg F May
004Temperature, water deg. fahrenheit30DA AVG <= 144.3 deg F Nov
004Temperature, water deg. fahrenheit30DA AVG <= 163.4 deg F Jul
004Temperature, water deg. fahrenheit30DA AVG <= 192.3 deg F Jun
004Temperature, water deg. fahrenheit30DA AVG <= 117.4 deg F Jan
004Temperature, water deg. fahrenheit30DA AVG <= 121.5 deg F Dec
004Temperature, water deg. fahrenheit30DA AVG <= 125.1 deg F Feb
004Temperature, water deg. fahrenheit30DA AVG <= 156.3 deg F Aug
004Temperature, water deg. fahrenheit30DA AVG <= 154.4 deg F Sep
004Temperature, water deg. fahrenheit30DA AVG <= 159.7 deg F Mar
004Temperature, water deg. fahrenheit30DA AVG <= 193.5 deg F Apr
004Temperature, water deg. fahrenheit30DA AVG <= 144.1 deg F Oct
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F May
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Nov
004Temperature, water deg. fahrenheitDAILY MX <= 163.4 deg F Jul
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Jun
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Jan
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Dec
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Feb
004Temperature, water deg. fahrenheitDAILY MX <= 156.3 deg F Aug
004Temperature, water deg. fahrenheitDAILY MX <= 207.4 deg F Sep
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Mar
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Apr
004Temperature, water deg. fahrenheitDAILY MX <= 212 deg F Oct
004Temperature, length of excursionDAILY MX <= 87.6 hr/12mo all year
004Chlorine, total residualDAILY MX <= .2 mg/L all year
004Chlorine, total residualDAILY MX <= 13.1 lb/d all year
004Chlorination durationDAILY MX <= 2 hr/d all year
008pHDAILY MN >= 6 SU all year
008pHDAILY MX <= 9 SU all year
008Solids, total suspended30DA AVG <= 30 mg/L all year
008Solids, total suspendedDAILY MX <= 100 mg/L all year
008Oil & Grease30DA AVG <= 15 mg/L all year
008Oil & GreaseDAILY MX <= 20 mg/L all year
008Oil & Grease30DA AVG <= 1.7 lb/d all year
008Oil & GreaseDAILY MX <= 2.26 lb/d all year

Built from EPA's ECHO bulk files. EPA's file, not the permit document, is the source: read your permit. Check a report before you file it · All states