(1) The following lands belong to the state of Montana to be held in trust for the benefit of the public schools of the state:
(a) all islands existing in the navigable streams or lakes in this state that have not been surveyed by the government of the United States; and
(b) all lands that at any time in the past constituted an island or part of an island in a navigable stream or lake.
(2) This section does not apply to lands that are occupied by and belong to riparian landowners if the lands were formed by accretions.
(3) State-owned riverbeds are public lands of the state that are held in trust for the people as provided in Article X, section 11, of the Montana constitution.