The outage was reported at about 7 a.m., and power was restored by about 8:10 a.m., SFPUC spokesman Tyrone Jue said.
Treasure Island often falls victim to outages caused by birds and other issues because of a lack of redundancies built into the system, Jue said.
"If a bird strategically hits a power line, it can cut off power to the whole island," he said.
The 404-acre island is still owned by the U.S. Navy and is in the process of being handed over to the city of San Francisco.
"We've done some upgrades to try to improve the redundancies, but there's only so much you can do without doing a whole capital overhaul," Jue said.