The Port of Long Beach Tuesday reached tentative agreement with a major terminal operator for the port’s first ship-to-shore electrical hookup that would reduce harmful diesel emissions.

The lease-amendment agreement with SSA Terminals, a joint venture of SSA Marine and Matson Navigation Co., will phase in the use of shore-side electricity known as “cold ironing” and other environmental technologies that will reduce diesel and nitrogen oxide emissions by as much as 90 percent over the next decade.

This agreement is part of a broader “Green Port” strategy to reduce emissions at the port as community and political pressure mounts to address pollution problems at both the ports of Long Beach and Los Angeles.

In 2002, SSA Terminals signed a 20-year lease with the Port of Long Beach for a 68-acre facility on Pier C. Under the revised lease, the Port will invest in the dockside electrical infrastructure, while SSA Terminals will upgrade its ships to accommodate electrical hookups.

Environmental groups and community activists have pushed both the ports of Los Angeles and Long Beach to switch to shore-side electrical hookups to eliminate the need for ships to belch diesel fumes while docked in port. Two years ago, the Port of Los Angeles inaugurated its first cold-ironing hookup at the China Shipping Container’s Berth 100 terminal.