16 U.S.C. § 403h–13

There is hereby authorized to be appropriated for construction of an entrance road on land acquired pursuant to section 403h–12 of this title not more than $2,500,000 (1969 prices), plus or minus such amounts, if any, as may be justified by reason of ordinary fluctuations in construction costs as indicated by engineering cost indexes applicable to the types of construction involved herein.