The department of transportation may provide for the construction of an extension of state route number 504 from the vicinity of Maple Flats to the vicinity of the United States Corps of Engineers debris dam on the north fork of the Toutle river on an alignment to be approved by the department of transportation. The department may enter into an agreement with the principal owner of the necessary right-of-way providing as follows:

(1) The owner of the right-of-way shall construct the highway extension and public parking facilities as specified by the department of transportation.

(2) The owner of the right-of-way shall convey to the state, right-of-way for the highway extension a minimum of one hundred fifty feet in width (except right-of-way presently under the control of the department of natural resources), together with areas for public parking facilities as designated by the department of transportation.

(3) The department of transportation shall reimburse the present owner of the right-of-way for the actual cost of construction of the highway extension and the public parking facilities.

(4) The construction of the highway extension and public parking facilities shall be completed within one year after March 27, 1982.

The department of transportation may acquire that part of the right-of-way necessary for the highway extension that is now under the control of the department of natural resources in the manner provided in RCW 47.12.023 through 47.12.029.

All expenditures by the department of transportation pursuant to this section shall be from appropriations for the construction of category A projects.