Who issues NPDES permits in Delaware?

Delaware Department of Natural Resources and Environmental Control issues and enforces NPDES permits for wastewater discharges in Delaware. Klarifi tracks 9 permits held by publicly owned treatment plants in the state.

How many NPDES permits in Delaware are expired or administratively continued?

1 permits are administratively continued (the plant applied for renewal and the old permit stays in force) and 2 are recorded as expired, out of 9 permits tracked. 6 are effective.

How many Delaware wastewater permits come up for renewal soon?

1 in 2026, 2 in 2028 and 3 in 2030. Each year has its own renewal calendar with the plants listed.

How do I look up an NPDES permit number?

Enter the permit number (two letters and seven characters, for example TX0021873) or the plant name in the lookup on the NPDES page; each result opens the plant profile with status, expiry, design flow and the three-year violation count.

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NPDES permits in Delaware

Name: NPDES permits held by wastewater treatment plants in Delaware
Creator: Klarifi
License: https://klarifi.io/terms-of-service

9 permits held by publicly owned wastewater treatment plants · issued by DNREC

Effective

Administratively continued

Expired

Total tracked

Delaware Department of Natural Resources and Environmental Control (DNREC) runs the NPDES program in Delaware under delegation from EPA Region 3, issuing and enforcing the discharge permits listed here. Klarifi tracks 9 permits held by publicly owned treatment plants in the state, with status, expiry, design flow and three-year compliance for each. Agency website →

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.

Permit renewals by year

2026: 1 permits

2028: 2 permits

2030: 3 permits

Largest permit holders in Delaware

The 25 largest publicly owned wastewater treatment plants in Delaware by permitted design flow, with NPDES permit number, status and expiry. Source: EPA ICIS-NPDES via Klarifi.
Facility	City	Avg flow (MGD)	Design (MGD)	NPDES permit	Status	Expires	Violations (3y)
Wilmington Wastewater Treatment Plant- 12th St & Hay Rd, Wilmington	Wilmington	78.67	—	DEL020320	Effective	Dec 2030	5
South Coastal STP	Frankford	4.6	—	DEL050008	Effective	Dec 2030	5
Seaford Wastewater Treatment Plant	Seaford	1.57	—	DE0020265	Administratively continued	Oct 2020	0
Selbyville Wastewater Treatment Facility	Selbyville	1.26	—	DE0020010	Effective	Apr 2028	1
Howard Seymour Water Reclamation Plant	Lewes	1.05	—	DE0021512	Expired	Oct 2023	1
Delaware City Wastewater Treatment Plant	Delaware City	0.37	—	DEL021555	Effective	Dec 2030	2
Laurel Water Department	Laurel	0.34	—	DE0020125	Effective	Oct 2028	62
Milton Wastewater Treatment Plant	Milton	0.23	—	DE0021491	Expired	Apr 2016	11
Port Penn Wastewater Treatment Plant	Port Penn	0.03	—	DE0021539	Effective	Oct 2026	1

All 9 plants in Delaware →

NPDES permits in Delaware: questions

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.

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