The board shall employ investment counsel on its staff or on a consulting basis or trust companies or trust departments of bands to render service in connection with the board’s investment program.

Whenever the board elects to contract with outside firms for investment counseling services it shall obtain proposals from all interested firms and conduct a public meeting at which a consultant or consultants shall be selected by the board. At least once in each three-year period after the prior selection, a consultant or consultants shall be obtained by the same procedure upon submission of new proposals.