Related by context. Frequent words. (Click for all words.) 61 fracking 61 hydraulic fracturing 54 contaminate groundwater 54 toxic chemicals 53 chemicals 52 groundwater 52 hydrofracking 51 drillers 51 contaminants 51 contaminate drinking 50 aquifers 49 contaminated groundwater 49 Fracking 49 frack 49 fracing 48 hexavalent chromium 48 gasoline additive MTBE 48 aquifer 48 perchlorethylene 48 Safe Drinking Water 48 hazardous chemicals 48 carcinogens 47 MTBE 47 shale formations 47 groundwater contamination 46 chemical 46 perchlorate 46 shale 46 toxic substances 46 harmful chemicals 46 hydrofluoric acid 45 contaminant 45 chemical additives 45 COGCC 45 trichlorethylene 45 wells 45 wastewater 45 drilling fluids 45 Aquifer 44 vinyl chloride 44 underground aquifers 44 gasoline additive 44 radionuclides 44 solvents 44 Hydraulic fracturing 44 hydrocarbons 44 hexane 44 chlorine 44 methyl tertiary butyl ether 43 pollutants 43 toxins 43 sludge 43 toxic pollutants 43 coalbed methane 43 #,# dioxane 43 benzene 43 coal slurry 43 tritium 43 fly ash 42 trace amounts 42 hazardous substances 42 slurry 42 geological formations 42 toxic wastes 42 Marcellus Shale formation 42 sewage sludge 42 coal ash 42 carcinogen 42 underground aquifer 42 contaminated 42 methane 42 radioactive tritium 42 xylene 42 poisonous chemicals 42 Superfund Site 42 chemical compounds 42 contaminated soil 41 arsenic 41 liquids 41 Marcellus shale 41 hydrogen sulphide 41 Marcellus Shale 41 PFOS 41 hydrolyzate 41 PFOA 41 geologic formations 41 hazardous material 41 fumigants 41 harmful toxins 41 natural gas 41 hydrogen sulfide 41 water 41 sediment 41 hydrocarbon 40 septic systems 40 bed methane 40 Ogallala Aquifer 40 trihalomethanes 40 underground piping 40 substances 40 Clean Water Act