If the portion of the system they wish to improve is the federal portion, with their funds, they will need to proceed and ask permission through the 408 process. Such modifications must be approved by the Chief of Engineers. The authorities and procedures for major changes to an existing authorized project are outlined in: the 17 November 2008 Clarification Guidance on the Policy and Procedural guidance for the Approval of Modifications and Alterations of USACE Project; ER1165-2-119, dated 20 September 1982, Modifications to Completed Projects; and 33 USC 408, Taking Possession of, Use of or Injury to Harbor and River Improvements.
If the portion of the project does not have a tie-in or any effect on the existing authorized project, then the non-Federal partner may proceed through the normal permitting process.
If the non-Federal partner wants to proceed with a project that may have an impact on the Federal project even though they are not touching the Federal project, then the 408 process must be followed.
If there is an ongoing or proposed study to consider alternative solutions, the non-Federal partner must follow the 408 process and must also submit the necessary package for proposed credit (Section 104 of WRDA 1986 or Section 2003 of WRDA 2007), which must be submitted at the same time for approval by the Secretary of the Army for Civil Works. This is to allow the non-Federal sponsor credit for work completed ahead of Federal authorization and funding of the construction project.
To initiate a new study based on additional protection required from an existing project, an initial study can be performed under Section 216 of the Flood Control Act of 1970. The procedure is outlined in ER 1165-2-119, Modifications of Completed Projects, dated 20 September 1982. They may also follow the process to initiate a new study, starting with a Reconnaissance Report (ER 1110-2-100, Planning Guidance Notebook).