Any city entering into an agreement with the United States of America or any agency or instrumentality thereof pursuant to Kan. Stat. Ann. §§ 12-2718 through 12-2721 and acts amendatory thereof or supplemental thereto which, under the terms of such agreement, is required to transfer ownership of its existing water storage facility or facilities in exchange for storage rights producing at least the same firm yield of water as the facility or facilities transferred, shall not be subject to the fifteen percent (15%) maximum limitation on the amount it may reimburse the United States of America or its agency or instrumentality under Kan. Stat. Ann. § 12-2719.