Related by context. Frequent words. (Click for all words.) 66 trihalomethanes 65 fecal coliform bacteria 64 fecal coliform 63 turbidity 62 arsenic 62 coliform 61 contaminants 60 nitrate 60 contaminant 58 perchlorate 58 mg l 58 hexavalent chromium 57 coliform bacteria 57 fecal bacteria 57 dissolved oxygen 57 groundwater 57 pollutant 56 trichlorethylene 56 chloride 56 benzene 55 nitrates 55 hydrogen sulfide 55 leachate 55 tritium 55 suspended solids 54 PAHs 54 ppb 54 chromium 54 chlorides 53 sulfate 53 alkalinity 53 dioxin 53 pollutants 53 toxicity 53 contaminated groundwater 53 fluoride 53 phosphorus 52 vinyl chloride 52 cyanuric acid 52 dioxins 52 radium 52 selenium 52 manganese 52 groundwater contamination 52 cyanobacteria 51 chlorination 51 concentrations 51 chlorine 51 PFOS 51 cryptosporidium 51 methylmercury 51 endotoxin 51 radioactive iodine 51 toxin 50 TCE 50 wastewater discharge 50 sewer overflows 50 hydrogen sulphide 50 wastewater 50 effluent 50 fecal contamination 50 PFOA 50 ATSDR 50 treated effluent 50 uric acid 50 aquifer 50 phosphorous 50 toxins 50 nanograms per 50 cotinine 49 radionuclides 49 e coli 49 nutrient pollution 49 ozone 49 contamination 49 radioactive tritium 49 fine particulate matter 49 carbon monoxide 49 sedimentation 49 Nitrate 49 barium 49 VOCs 49 sulphate 49 naturally occurring 49 toxic pollutants 49 NO2 49 picocuries per 48 radioactive cesium 48 radon 48 salinity 48 acetaldehyde 48 sediment 48 H2S 48 metabolites 48 sewage overflow 48 nitrogen 48 PCBs 48 particulate 48 air toxics 48 iodine 48 SO2