SEATTLE — Washington State Ferries has awarded a $100 million contract to Vigor to retrofit hybrid electric propulsion systems into two of its Jumbo Mark II ferries with an option to retrofit the third for an additional $50 million, according to a Department of Transportation press release.

The department had estimated a cost of $120 million to retrofit the three vessels; Vigor’s $150 million bid was the lowest, the next lowest bid was $166 million.

Sen. Maria Cantwell’s office has announced that $44.6 million of this contract will be covered by federal funding.

Cantwell, the chair of the Senate Committee on Commerce, Science, and Transportation, has supported low- and no-emission transportation projects including $11.6 million to electrify Washington State Ferries’ Mukilteo-Clinton route and $25 million to replace Whatcom County’s 60-year old M/V Whatcom Chief with an electric hybrid vessel on its Lummi Island ferry route.

The M/V Wenatchee will go to Vigor’s Harbor Island shipyard in September to begin its refit and is expected to return to service on the Bainbridge Island-Seattle route next summer.

It will be followed next year by the M/V Tacoma, which is also on the Bainbridge Island-Seattle route.

During the retrofit of the Wenatchee and Tacoma, other vessels will be shifted to the Bainbridge Island route to minimize service disruptions, according to a spokesperson for the ferries division.

The contract includes an option to convert the M/V Puyallup, currently in service on the Kingston-Edmonds route, during 2025.

The Jumbo Mark II-class ferries are the largest vessels in service with the ferry system and contribute 26 percent of the system’s greenhouse gas emissions.

The retrofit is expected to decrease their emissions by 95 percent.

Each of the three vessels is 460 feet long, 90 feet from side to side and can carry 202 passenger cars.

The contracted configuration changes will not affect vessel capacity or speed.

The system was designed to adequately charge during the system’s current 20-minute dwell time for unloading and loading passengers and vehicles.

The three vessels entered service in 1997, 1998 and 1999 and, in addition to retrofitting the propulsion system, they will also they will also receive new control systems, which should extend their service lives for another 40 years.

Washington State Ferries’ long-range plans include retrofitting six diesel ferries to hybrid electric, building 16 new hybrid vessels, retiring 13 diesel ferries and adding charging power to 16 terminals.