The issue of maintaining a balance between economic development and preservation of the environment is a major concern in Hawaii, which in 1961 became the first state in the nation to adopt sweeping statewide land use controls. Hawaii suffers from a very high dependence upon imported petroleum as its primary energy source, and has declared a policy of accelerating the transition to alternate energy sources. Geothermal energy is believed to exist in abundant quantity, especially on the Island of Hawaii. In order to ensure that geothermal development occurs in the most appropriate areas, the State in 1983 adopted legislation to establish geothermal resource subzones where geothermal activities may take place. Six subzones have subsequently been established.