NPDES permit lookup
Search 11,783 publicly owned wastewater treatment plants by permit number or name. Every result opens the plant with its permit status, expiry date, design flow, treatment technology and three-year violation count.
Effective permits
8,669
Administratively continued
2,130
Expiring in 2026
1,201
Expiring in 2027
1,872
Why permit expiry dates matter
An NPDES permit runs for five years. To keep discharging, a plant must apply for renewal at least 180 days before the expiry date, and the renewed permit usually arrives with tighter effluent limits, new monitoring requirements or a compliance schedule. That is why the year a permit expires is the year a plant starts budgeting for upgrades: nutrient removal, disinfection, capacity or controls.
NPDES permits by state
ADEM
53 expire 2027
ADEC
12 expire 2027
ADEQ
12 expire 2027
DEQ
45 expire 2027
SWRCB
28 expire 2027
CDPHE
0 expire 2027
DEEP
2 expire 2027
DNREC
0 expire 2027
FDEP
12 expire 2027
EPD
24 expire 2027
DOH
0 expire 2027
IDEQ
4 expire 2027
IEPA
293 expire 2027
IDEM
70 expire 2027
Iowa DNR
95 expire 2027
KDHE
56 expire 2027
KDOW
19 expire 2027
LDEQ
25 expire 2027
Maine DEP
6 expire 2027
MDE
7 expire 2027
EPA Region 1
17 expire 2027
EGLE
43 expire 2027
MPCA
35 expire 2027
MDEQ
20 expire 2027
MoDNR
65 expire 2027
MDEQ
27 expire 2027
NDEE
41 expire 2027
NDEP
1 expire 2027
EPA Region 1
4 expire 2027
NJDEP
33 expire 2027
EPA Region 6
4 expire 2027
NYSDEC
52 expire 2027
NCDEQ
9 expire 2027
NDDEQ
19 expire 2027
Ohio EPA
186 expire 2027
ODEQ
35 expire 2027
Oregon DEQ
19 expire 2027
PA DEP
109 expire 2027
RIDEM
0 expire 2027
SCDES
10 expire 2027
DANR
40 expire 2027
TDEC
41 expire 2027
TCEQ
244 expire 2027
Utah DEQ
1 expire 2027
VT DEC
5 expire 2027
VDEQ
36 expire 2027
Ecology
2 expire 2027
WVDEP
2 expire 2027
WDNR
1 expire 2027
WDEQ
8 expire 2027
NPDES permit questions
What is an NPDES permit?
An NPDES (National Pollutant Discharge Elimination System) permit authorises a facility to discharge treated wastewater to surface water under the Clean Water Act. It sets effluent limits, monitoring and reporting requirements, and runs for at most five years before it must be renewed.
How do I read an NPDES permit number?
A permit number is two letters and seven characters, for example TX0021873. The letters are the state; the digits identify the permit. General permits carry a G (for example ILG580094). Type the number into the lookup above to open the plant that holds it.
How many NPDES permits are administratively continued?
Of the 11,783 publicly owned plants in the directory, 8,669 hold effective permits, 2,130 are administratively continued (renewal applied for, old permit still in force) and 932 are recorded as expired.
How many wastewater permits expire in 2026 and 2027?
1,201 permits held by publicly owned plants expire in 2026 and 1,872 in 2027. Each state has a renewal calendar listing the plants by expiry month.
Where do I find the official permit document?
The issuing state agency (or the EPA region in Massachusetts, New Hampshire and New Mexico) publishes the permit and fact sheet. Each state page below names the agency and links to it; the plant profile shows the permit number to search for.
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 11, 2026.