This is one I missed while away at AGU in December. Bristol's seismologists weren't the only ones doing some monitoring down at Balcombe over the summer: the Environment Agency were performing water quality analysis before and after drilling, and have published their findings in a short report.
The most striking part of the report is the foreword:
We wanted to repeat the water quality sampling during the test-drilling to see if there were any changes. However, we weren't able to do this as access became difficult during the protestors' occupation of the area in August. We did, however, collect a sample from the borehole at this time and subsequently took samples from the Lower Stumble area when it became safe for our staff to do so.It seems that the "protectors" scored something of an own goal, actually preventing the EA from going about their testing.
Beyond that, there is little to report (hence why this wasn't picked up by the media). The borehole water was identified as containing methane prior to drilling, and methane concentrations are unchanged post drilling. These shallow methane accumulations are a naturally occurring phenomenon.
It seems there was a small increase in ammonia in some samples post drilling, although still well within acceptable limits. Although the EA do not cite any particular source for this ammonia, elevated ammonia levels can be caused by lots of people pee-ing in streams.