Water Quality in the Drummond Bog : Following Three Years of Municipal Wastewater Effluent Discharge

Abstract

Water chemistry in a peat bog functioning as an advanced wastewater treatment system for the town of Drummond, Wisconsin was monitored during the second and third year of operation (1980-81). Water quality data generated during this time period was compared to baseline data (Mechenic 1980) to determine changes in water quality resulting from wastewater discharge to the bog. Hydrologic information provided by the u.s. Forest Service was combined with the water chemistry data to determine treatment efficiency. In addition several test plots were treated with varying concentrations of municipal wastewater effluent so that the bog's response to higher wastewater loading rates could be examined. Effluent impact on the bog's water chemistry was most apparent at sites nearest the irrigation pipe used to discharge effluent across the surface of the bog. Significant (99% confidence level) water quality changes at the bog discharge and monitoring wells located more than 50 meters from the point of discharge were limited to increased conductivity and chloride values, along with decreased Chemical Oxygen Demand. Good wastewater treatment efficiencies were obtained during the 1980-81 period. Approximately 75% of the phosphorus and 45% of the nitrogen added to the system (wastewater and precipitation sources) was retained within the peat bog. Biological Oxygen Demand of the effluent was reduced by 66% during 1981. Although anomalies were present in the test plot data a correlation between increased wastewater loading rates and water quality degradation of the receiving interstitial water was observed. In addition to changes in water quality, plant species not native to the bog were observed growing near the effluent irrigation pipe during the Summer of 1981. Further information is needed to determine if this particular type of wetland can tolerate long term discharges of comparatively high pH municipal wastewater effluent. Wetlands having water quality similar to the typical municipal wastewater effluent may be better suited for use as advanced treatment systems.