(4) If, following hearings held under subsection (3) of this section, the director determines that the lack of milk regulation in neighboring states similar to the market area pooling plan proposed for this state would render such a pooling arrangement in this state ineffective or impractical, the director shall so state in writing. The director shall file the statement with the code reviser for publication in the Washington State Register. In such a case, a market area pooling plan shall not be established in the market area under subsection (3) of this section based upon the referendum that precipitated the hearings. If the director determines that such a lack of milk regulation in neighboring states would not render such a market area pooling plan ineffective or impractical in this state, the director shall adopt rules in accordance with subsection (3) of this section.