Mountains to Sound Greenway National Heritage Area Act

Mountains to Sound Greenway National Heritage Area Act - (Sec. 3) Establishes the Mountains to Sound Greenway National Heritage Area in the state of Washington, consisting of specified land in King and Kittitas counties.

Allows King or Kittitas county to elect at any time to be excluded from the Heritage Area.

Requires the Secretary of the Interior to select the local coordinating entity for the Heritage Area.

(Sec. 4) Requires the coordinating entity to submit a proposed management plan to King and Kittitas counties for approval before submitting the plan to the Secretary.

Requires the plan to include: (1) consideration of the state of Washington's government plans; (2) descriptions of partnership collaborations and actions that governments, private organizations, and individuals have agreed to take to protect the area; and (3) recommendations to coordinate federal, state, and local programs, including the role of the National Park Service (NPS).

Requires the Secretary to approve or disapprove the plan based on specified criteria, including whether the public and federal, state, tribal, and local governments were afforded an opportunity to be involved in the preparation of plan.

Authorizes the Secretary to provide technical assistance to the state, political subdivisions of the state, nonprofit organizations, and other interested parties.

(Sec. 5) Directs the Secretary, within 10 years after enactment of this Act, to submit to Congress a report evaluating the Heritage Area's coordinating entity, private and government investments, management structure, partnerships, and funding. Requires the report to include recommendations for the NPS's future role in the Heritage Area.

(Sec. 6) Directs the coordinating entity to report to the Secretary every five years after the Secretary has approved a management plan. Requires the report to specify the entity's expenses and income, as well as grants or contracts made by the coordinating entity to other entities.

Prohibits the coordinating entity from acquiring real property with federal funds or through condemnation.

(Sec. 7) Encourages federal agencies planning to conduct activities that may impact the Heritage Area to consult and coordinate with the Secretary and the local coordinating entity to the maximum extent practicable.

(Sec. 8) Prohibits this Act from altering the rights of property owners or affecting certain existing federal, state, tribal, or local projects, agreements, or regulatory requirements.

(Sec. 9) Declares that nothing in this Act authorizes the Secretary to allocate or distribute federal funds to the local coordinating entity or to expend federal funds for any purpose other than as specified in this Act.

(Sec. 10) Terminates the Secretary's authority to provide assistance 15 years after enactment of this Act.