Mahoney Lake Hydroelectric Project Licensing Act This bill requires the Federal Energy Regulatory Commission (FERC), upon request, to issue a stay of the statutory deadline by which construction must commence on the Mahoney Lake Hydroelectric Project located in Ketchikan Gateway Borough, Alaska. (The City of Saxman, Alaska, was granted a construction license for the Mahoney Lake Hydroelectric Project on January 22, 1998.) Additionally, upon request, FERC must reinstate the construction license and make it effective as of the date the stay is lifted. FERC may reinstate the construction license if it is expired. Subject to certain conditions, FERC may extend for up to six years the statutory deadline by which construction must commence on the project.