Geothermal Steam Act Amendments of 1987

Geothermal Steam Act Amendments of 1987 - Amends the Geothermal Steam Act of 1970 to provide that if geothermal steam is produced or utilized in commercial quantities under an approved operation within any lease or administrative lease extension period, such lease shall continue for so long as geothermal steam is produced (or utilized) in commercial quantities, for a maximum continuation of an additional 40 years.

Sets forth conditions under which geothermal leases in effect as of the date of enactment of this Act shall be extended for a maximum of three successive five-year periods.

Requires the Secretary of the Interior to review any cooperative or unit plan of development every five years after approval in order to eliminate any lease or part of lease not regarded as reasonably necessary to cooperative or unit operations. Requires such elimination to be based on scientific evidence, and only upon the Secretary's determination that it is for the purpose of conserving and properly managing the geothermal resource.