1977—Pub. L. 95–105 inserted “based on December 1975 prices, plus or minus such amounts as may be justified by reason of ordinary fluctuations in operation and maintenance costs involved therein,” after “$30,000”.

1973—Pub. L. 93–126 substituted “$30,000” for “$20,000”.

Amendment by Pub. L. 95–105 effective Oct. 1, 1977, see section 514(d) of Pub. L. 95–105, set out as a note under section 277d–3 of this title.