Well logs for the eight Mason City municipal drinking water wells, which are within 2 miles of the site, indicate that six of the wells are uncased through portions of the Cedar Valley aquifer. The Cedar Valley aquifer yields water to the municipal wells. Approximately 98 percent of the population of Mason City is supplied by the municipal drinking water supply. High concentrations of PAHs have been detected in samples of ground water collected from the uppermost aquifer, and in samples of Willow Creek sediment downstream from the site. Site characteristics indicated the potential for PAH-contaminated ground water in the uppermost aquifer to discharge to the surface water.
Willow Creek is used for public recreational fishing.
The FS is expected to be completed during the first quarter of fiscal year 1995. This is for the purpose of selecting a removal action. The description may change as additional information is gathered on the sources and extent of contamination.