I never really paid any attention to this issue until I moved to OK. I had only ever been through one earthquake before, the one that hit the east coast in summer of 2011. After experiencing several earthquakes shortly after moving to OK (none of them have been anywhere near the scale of that one on the east coast), and remembering something about earthquakes possibly being related to fracking, I started doing some research. I had never lived in an area that had any fracking going on, but being oil country, OK is one of the fracking capitals of the universe. There seems no be no real conclusive info out there that ties earthquakes to fracking, but there is PLENTY of empirical evidence that says it is absolutely so. Scientists seem to be paid off to not make any definite conclusions, everything is a "maybe".
Earthquakes aren't the only impact that fracking has, however. There have been proven instances of water wells being damaged and polluted. There are well blowouts that spray nasty chemicals over someone's property. The nasty chemicals used in the fracking solution ("mud") are quite poisonous, and are pumped back out of the (fracked oil or gas) wells, left lying around in open pits for temporary storage, and then injected back into the earth in deep "disposal wells" (or "injection wells"). Livestock has been poisoned and killed when drinking from those open fracking pits. It is claimed that the mud is injected deeply enough into the earth's surface that it could never possibly cause any sort of groundwater contamination or other environmental damage. One of the major producers of these chemicals is halliburton, IIRC (I'd have to double check that, but I remember it being one of those type of companies with shady dealings and government connections). This fracking waste is also exempt from the clean water act environmental law, and can be disposed of with virtually no oversight, unlike virtually any other form of toxic waste.
Fracking (any oil or gas drilling company, actually) can just come onto someone's land and do their thing, regardless of if the owner wants them there, in many places that have historically had oil, gas, and mining operations. This is because land and property is sold as a "split estate" rather than in "fee simple". What this means is that mineral rights are sold separately from surface rights to the land. You own the land, but not what is underneath it. In OK, it is virtually impossible to buy land in fee simple unless it is a large (100+ acres) has been owned for 100 years by the same family who never sold (or leased) the mineral rights off and they actually sell it that way. Usually in that situation, the mineral rights are sold off first, before the surface rights, and there is never any chance to buy in fee simple - you'd have to get EXTREMELY lucky.
I'm not an environmentalist tree-hugging type by any means, but I do think there are some very valid concerns with this fracking business. I'll admit that I'm pretty much undecided, and don't have a conclusive opinion one way or the other. I do believe that if we have oil here in the US, we should absolutely do what we need to do to get it out of the ground and use it, rather than have to buy so much of it from other countries. But fracking has caused domestic production to increase by huge amounts, and not only has there not been any decrease in prices of things like gasoline or natural gas, we have ended up increasing our exports of those resources. This makes no sense to me. And at what price does this come? How many poisoned wells is it worth? What if we discover a groundwater supply for an entire town near an injection well has been poisoned? I don't seem to see any benefits to us consumers from the fracking, but the potential risks seem to be huge. Direct and proven damage has been small and localized in nature so far. But what if some sort of harm is proven on a larger scale? After so many years, the damage will have already been done before we discover it, and cannot reverse it.
I feel that the OH law is a step in the right direction. Fracking needs to be much more closely watched and studied. Fracking should absolutely not occur on or near fault lines (read the fracking and earthquakes studies), but unfortunately those are considered some of the most productive areas to drill. The risk of damage or other ill effects is probably minimal, if the fracking is done carefully. Some companies have been much more sloppy in their work than others. I don't claim to know all that much about fracking (or the oil and gas drilling industry in general, for that matter), but if anyone is further interested in the topic, I can point them in the right direction for further research.