What is a NPDES permit?
NPDES permit: National Pollutant Discharge Elimination System
An NPDES permit is the licence, issued under the Clean Water Act, that allows a facility to discharge treated wastewater to a river, lake or coastal water. NPDES stands for National Pollutant Discharge Elimination System; the permit sets the pollutant limits the effluent must meet, the monitoring and reporting the discharger must do, and the schedule for any upgrades, and it runs for five years before renewal. Forty-seven states issue their own permits under EPA authorisation; the EPA issues them directly in Massachusetts, New Hampshire, New Mexico and the territories. Klarifi tracks the permits of 11,783 publicly owned treatment plants and lets anyone look one up by number or plant name.
What an NPDES permit contains
Effluent limits for conventional pollutants (BOD, suspended solids, pH, bacteria), and for ammonia, nutrients, metals or toxics where the receiving water needs them; monitoring requirements that produce the monthly discharge monitoring reports the EPA publishes; special conditions such as pretreatment programs, biosolids rules and compliance schedules; and the permit number, two letters for the state and seven characters, for example TX0021873.
Renewal, and why suppliers watch expiry dates
A permittee must apply for renewal at least 180 days before the five-year term ends. If the agency has not reissued the permit in time the old one is administratively continued and stays enforceable. Renewed permits usually arrive with tighter limits based on newer water-quality standards, which is what triggers nutrient removal, disinfection and capacity projects; the expiry year is therefore the year a plant starts budgeting for upgrades.
Violations and enforcement
Each monitoring report is compared with the permit limits; an exceedance is an effluent violation, and missed reports are violations too. Repeated violations lead to notices, consent orders and penalties, and they are public through the EPA’s ECHO system. Klarifi shows a three-year violation count on every facility page.