The Water Infrastructure Finance and Innovation Act (WIFIA) was signed into law by the President on June 10, 2014, and authorized the WIFIA program to be managed by EPA Headquarters. WIFIA was amended by section 1445 of the Fixing America's Surface Transportation Act of 2015 (FAST), section 5008 of the Water Infrastructure Improvements for the Nation Act of 2016 (WIIN), and section 4201 of America's Water Infrastructure Act of 2018. The statute and its amendments are in 33 USC Ch. 52: Water Infrastructure Finance and Innovation.

The interim final WIFIA implementation rule, Credit Assistance for Water Infrastructure Projects (11 pp, 207 K, About PDF), was signed by EPA on December 6, 2016, and establishes the guidelines for the WIFIA program and the process by which EPA will administer credit assistance. The interim final Previously-Incurred Costs in the WIFIA Program was signed by EPA on June 18, 2018 and amends the WIFIA regulations to clarify the process and conditions for including costs incurred and the value of integral in-kind contributions made before loan closing in the calculation of total eligible costs. It also explains the process for being reimbursed for those eligible costs by WIFIA loan proceeds.

The final fee rule, Fees for Water Infrastructure Project Applications under WIFIA, was signed by EPA on June 19, 2017, and establishes the fees related to the provision of federal credit assistance under WIFIA.

EPA and the Bureau of Reclamation signed a Memorandum of Understanding on October 24, 2019 to advance federal collaboration on funding water infrastructure projects.

Similarly, EPA and the United States Army Corps of Engineers signed a Memorandum of Understanding on July 30, 2018 to establish a framework for working together to implement certain provisions of WIFIA.