43 CFR § 429.24
When should I pay my use fee?
June 11, 2020
(a) If Reclamation offers you a use authorization, you must pay the use fee in advance, unless you are granted a waiver under subpart F of this part.
(b) Your use authorization will clearly state the use fee. Should periodic payments apply, your use authorization will also describe when you should pay those periodic use fees.