Amends federal law designating segments of the Lower Merced River for inclusion in the Wild and Scenic Rivers System and providing that such designation shall not affect the continued operation and maintenance (including flood control operations) of the New Exchequer Project to define "flood control operations" to include occasional short-term increases in the level of Lake McClure not to exceed elevation 877 feet mean sea level for not to exceed 60 days between May 1 and July 31 of above-normal water years, as defined by the San Joaquin Valley 60-20-20 Hydrological Classification Index, developed by the California State Water Resources Control Board, or any successor index applicable to the Merced River watershed.