The purpose of this chapter is to establish and set forth the policies and procedures of the department of ecology in regard to the protection of the occurrence and availability of groundwater within the upper aquifers or upper aquifer zones where there are multiple aquifer systems. Consistent therewith, the department shall manage the state's groundwater resources in a manner that protects, to the extent practicable, the upper aquifers of multiple aquifer systems from depletions, excessive water level declines or reductions in water quality, and which recognizes that the highest and best use of the waters of limited capacity aquifers may be for domestic, stockwater and other similar uses and for the preservation of spring and stream flows.