This article is relevant to fracking here in Huerfano County given Huerfano's varied, deep geology containing many faults and fractures in addition to dikes (the dikes themselves may also form conduits to surface aquifers).
US DOE testing for links between faults, groundwater pollution
"Speaking at a congressional briefing in Washington, Hammack said faults "form a plane that allows fluids to move up through the frack." Some faults can be easily seen and avoided, but Hammack said some faults are not easily detected and could extend from the Marcellus Shale formation into other formations close to the surface."
This is why we need no hydraulic fracturing in Huerfano until a hydrogeological study is completed.
SWEPI (Shell) has already told us they will not frack the first well in the forum and in the newspapers. Now, on all their drilling plans it even states: "Frac'ing or additional reservoir stimulation methods will not be applied to this first exploration well." (See bottom of page 2 here for example). Is that a guarantee for all 4? It should be a Condition of Approval on all the permits from the COGCC.