Marrowstone Island, WA | Region 10 | US EPA

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Marrowstone Island, WA

EPA Region 10 received a petition from the Marrowstone Island Community Association on August 27, 1991, which requested EPA to designate Marrowstone Island as a Sole Source Aquifer. The population of the Island varies by season, from about 600 in the winter, to about 1,300 during a peak summer weekend.

EPA's review of the petition and other data determined that:

Water quality studies have discovered elevated chloride concentrations that indicate seawater intrusion is occurring in the fresh water aquifer system underlying the Island. This intrusion of seawater is the result of increased pumping of the aquifers, which is attributable to the increase in Island population.

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Designation (Federal Register - as proposed)
Support Documents
Sole Source Aquifer Maps

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