The drinking water source for Mountlake Terrace is
surface water and snowmelt that flows to the Lake Spada Reservoir in the Sultan
Basin through a pipeline to the Chaplain Reservoir, and then through four large
transmission lines to Everett. The City of Everett manages water treatment and
distribution to various water purveyors in Snohomish County through a water use
agreement. Everett supplies water to the Alderwood Water District; who in turn
supplies water to the City of Mountlake Terrace.