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This data layer was created in 2009 by Geographic Technologies Group (GTG), the GIS consultants for the City of Unalaska. The GIS layer was created from an AutoCAD file. GTG converted the AutoCAD file into GIS and georeferenced it using monumentation set in Alaska State Plane Zone 10. It was originally created as two separate layers: control valves and mainline valves. In 2015, those layers were merged into Control Valve to fit the LGIM schema. Since its creation in 2009, the data has been updated and maintained by the City of Unalaska. |