A review of the contributory factors affecting water quality in the Drumcliff Springs, Co. Clare

Abstract

The water supply for Ennis town and its environs is taken from Drumcliff Springs whose recharge area is a karst aquifer. Previous studies have indicated that due to the geology of the catchment, the varying thickness in the overlying soils and fast travel time in the groundwater flow regime, there is minimal attenuation of contaminants, both natural and anthropogenic, thereby making the groundwater and the Drumcliff Springs supply well extremely vulnerable to pollution. In addition to the known contributory factors resulting from the geological nature of the catchment, there are significant hazards associated with anthropogenic activities occurring within the catchment that are giving rise to risks of contamination of the supply. The objective of this study is to review data generated during the past seven years, within the context of the above. The evaluation of this analytical water quality data available indicates that there has been no deterioration in water quality suggesting that the groundwater protection plan in place for the catchment is effective to some degree. The lack of correlation observed between rainfall and the parameters colour, turbidity and iron, leaves the water supply very vulnerable to a wide variation in water quality in the supply until such time as increased treatment is put in place. Nutrient levels observed are low. Risk of elevated nutrient levels can arise from septic tanks, wastewater treatment systems for single houses, municipal and commercial facilities and from the landspreading of organic waste. A link was observed between rainfall and elevated microbial levels and because of the karst nature of the catchment, a real danger still exists of contamination of the supply, in particular from microbial pathogens entering the groundwater, as a result of both agricultural activities and single house developments and municipal activities. In addition a similarly significant danger exists from hazardous materials, i.e. from hydrocarbons and other hazardous substances that are in use within the catchment, whether they are used as part of commercial operational processes, or in the storage of the hazardous materials, e.g. in petrol stations or in fuel tanks on farms or for home heating, or as a result of a large road-side spillage, resulting in a major emergency event. It will be difficult to control the water quality in the supply unless proposed developments are planned in a sustainable manner and good practice is adopted in the management of waste materials arising in the catchment. Public awareness of the groundwater vulnerability is required to maintain good water quality status. The implications for the water supply and the associated public health issues remains a serious concern. Ongoing and indeed increased monitoring of the water quality within the catchment, together with sustainable management, landuse planning of activities that generate wastes and public co-operation is required if the risk of contamination from the various hazards existing is to be minimised.