Two or more counties each with a population of from eight thousand to less than one hundred twenty-five thousand at the time of creation of the regional law library may, by agreement of the respective law library boards of trustees as described in RCW
27.24.020(2), create a regional law library and establish and maintain one principal law library at such location as the regional board of trustees may determine will best suit the needs of the users: PROVIDED, HOWEVER, That there shall be at all times a law library in such size as the board of trustees may determine necessary to be located at the courthouse where each superior court is located.