There's an old saying that I won't spell out completely, but which most readers will certainly have heard at least once in their lives, to wit: "Don't sh-- where you eat." It is an all-purpose warning about not pursuing incompatible activities in the same place, particularly activities that produce either physical waste or emotional complications. In this case, the waste part is wastewater emitted by oil wells drilled into shale deposits, which must undergo extensive hydraulic fracturing (often called fracking) before the oil can be freed. What…