 How do we determine how water levels might be changing? Well we can go to a whole bunch of groundwater wells, take a little water level dipper to actually measure water levels and then we can map where the water wants to move to and then we can have a look through a whole bunch of what we call bore logs. So we basically describe the geology as we drill these wells to work out where these sand rich layers, where are these clay rich layers and then we can feed that information into a numerical model to try to figure out how water actually does move through these systems. Now one of the other implications of moving a lot of this water through, you get this condition known as groundwater drawdown, it induces flow to the area where you're removing groundwater out from the system and what that can do is actually speed up how water moves through these systems and if we speed up the water or slow it down we can also impact on how the water is interacting with minerals and stored salts in the aquifers so we can actually start changing the water quality as well. So even though we may not have removed enough groundwater to drop the water levels that people can no longer access it, there is actually the potential to start changing the salt low composition of these waters and not to mention as well the groundwater particularly in the Colseam can be quite saline it's been interacting with a lot of decomposing organic material for quite a long period of time. So there's a lot of other hydrocarbon components available in it not just the methane but you may have heard of things like BTECs and a few other hydrocarbons in there as well but also living organisms the cells in our body are actually quite saline so decomposing all that organic material also adds a lot of salt into the groundwater.