Portland is offering its island residents a $20 per month parking subsidy at the Ocean Gateway parking garage, the city announced Friday.

Up to 100 year-round island residents will be eligible for the program, which begins Sept. 1 and runs until June 30, 2011.

The program addresses the need for more parking for island residents while alleviating some of the city’s financial obligations to the parking garage. The idea came from the Peaks Island Council in response to the need for more mainland parking for islanders.

Portland residents will have to present a copy of their driver’s license with an island address to the parking garage’s manager at 167 Fore St. to be eligible. If the address is a P.O. box, proof of voter registration will be required.

Island residents already parking in the garage are also eligible for the subsidy and must present the same identification.

In order for the subsidy to be continued after June 30, the program will have to go through the city’s budget process.

The parking garage is at the corner of Fore and Hancock Streets, a couple of blocks away from the Casco Bay Ferry Terminal.

For more information, call the city’s parking division at 874-8444.