; (4) the local water authority waives all claims against the United States and the National Guard for treatment expenses incurred before the fiscal year during which the treatment is taking place; and (5) the cost of any treatment provided pursuant to subsection (a) does not exceed the actual cost of the treatment attributable to the activities conducted by or paid for by the Department of the Army or the Department of the Air Force, as the case may be. (c) Existing agreements Treatment of drinking water pursuant to subsection (a) may be provided without regard to existing contractual provisions in agreements between the Department of the Army, the Department of the Air Force, or the National Guard Bureau, as the case may be, and the State in which the base is located relating to environmental response actions or indemnification. (d) Authority To enter into agreements The Secretary concerned may enter into such grants, cooperative agreements, or contracts with a local water authority as may be necessary to implement this section. (e) Use of DSMOA Using up to $45,000,000 of the funds authorized to be appropriated by section 301 for operation and maintenance, the Secretary concerned may pay, utilizing an existing Defense-State Memorandum of Agreement, costs that would otherwise be eligible for payment under that agreement. (f) Termination of authority The authority under this section shall terminate on September 30, 2021. (g) Retroactive effect Notwithstanding paragraphs (1), (3), (4) of subsection (b), the Secretary concerned may reimburse a local water authority or a State for the treatment of drinking water pursuant to this section if— (1) the local water authority or state requested such a payment from the National Guard Bureau prior to March 1, 2018, or the National Guard Bureau was aware of a treatment plan by the local water authority or state prior to that date