Applications for NPDES permit renewals are required how many days before the permit expires?

• A. 90 Days
• B. 120 Days
• C. 180 Days
• D. 210 Days

Answer: (C)

Submitting the renewal well in advance gives the permitting authority enough time to review the request, verify compliance, and complete any processing steps (including public notice or conditions if needed). This lead time helps ensure that a new permit is in place before the current one expires, so there’s no gap in authorization to discharge. If the renewal is sent too close to expiration, processing can be delayed and a lapse could occur; submitting too early isn’t usually required and can be unnecessary. So, the standard lead time is about half a year before the permit expires.