Surface water and groundwater have often been studied and managed as separate resources, although they are interrelated.<ref name="circ1139">United States Geological Survey (USGS). Denver, CO. [http://pubs.water.usgs.gov/circ1139/ "Ground Water and Surface Water: A Single Resource."] USGS Circular 1139. 1998.</ref> There are three recognized classifications of groundwater which jurisdictions may distinguish: subterranean streams, underflow of surface waters, and percolating groundwater.<ref>http://www.blm.gov/nstc/WaterLaws/california.html</ref>
==== Policy maker's constituencies====
Classification of sites of policy makers' concern include:
* Consistency with national regulations
* and several other activities with practices that could degrade water quality.