Publication Summary

A ground water quality investigation was conducted in the Rochester vicinity to determine if wastewater discharge to an unlined flood channel from the Steelhammer Salmon Farm was affecting ground water. The hydrogeology near the facility consists of a single, highly transmissive aquifer system that is susceptible to contamination. Water quality samples from 22 wells, three surface water stations and wastewater effluent were obtained and tested.

A ground water quality investigation was conducted in the Rochester vicinity to determine if wastewater discharge to an unlined flood channel from the Steelhammer Salmon Farm was affecting ground water. The hydrogeology near the facility consists of a single, highly transmissive aquifer system that is susceptible to contamination. Water quality samples from 22 wells, three surface water stations, and wastewater effluent were obtained and tested.

Findings of the investigation show that the ground water flow pattern and quality is affected by the facility discharge. At least two feet of mounding was observed in one well located about 200 feet from the discharge channel. Wells downgradient of where the wastewater is ponded in the discharge channel show elevated concentrations of iron and total organic carbon and to a lesser extent total and fecal coliform bacteria, phosphorus and ammonia. Six wells near the ponded area showed iron concentrations that exceeded the secondary Maximum Contaminant Level (MCL) for public water systems. Comparisons with water quality results from 1986 show that ground water quality has deteriorated. Alternative discharge methods should be implemented because continued degradation of ground water is likely if disposal of wastewater to the channel continues. Two public wells are located near the affected area and a potential for their eventual contamination exists.

Link to EIM data for User Study ID SWSTHM01