ERP rules currently allow permittees seeking certain minor modifications to their permits to apply by letter, provided the proposed modification does not: 1) substantially alter the permit authorization; 2) increase the authorized offsite discharge; 3) impact the environmental features of the project; 4) decrease the required retention/detention; 5) decrease the required flood control elevations for roads or buildings; 6) decrease pollution removal efficiency; or 7) renew or extend the permit duration. Letter modifications are processed without an application fee. Permittees seeking to extend their permit duration must submit a formal modification application and fee, and a determination must be made that any completed construction is in compliance with the current permit. The proposed rule amendments will allow applications to extend the duration of an ERP to be made by letter, and eliminate the requirement for a determination of construction compliance with the current permit. Rule amendments also eliminate use of the term “renewal” in favor of the term “extension” to avoid confusion.