23 CFR § 661.35
What percentage of IRRBP funding is available for use on BIA and Tribally owned IRR bridges, and non-BIA owned IRR bridges?
May 21, 2020
(a) Up to 80 percent of the available funding made available for PE and construction in any fiscal year will be eligible for use on BIA and Tribally owned IRR bridges. The remaining funding in any fiscal year will be made available for PE and construction for use on non-BIA owned IRR bridges.
(b) At various times during the fiscal year, FHWA will review the projects awaiting funding and may shift funds between BIA and Tribally owned, and non-BIA owned bridge projects so as to maximize the number of projects funded and the overall effectiveness of the program.