There has been some discussion here at the Myvatn Research Station in the last few days about the possible impact of the planned geothermal power plant in Bjarnarflag, only a short distance from Lake Myvatn and in the middle of the natural groundwater channels feeding the lake with mineral rich water. Most of the water in the lake originates in such groundwater channels and emerges in artesian springs at the lake shore (photo). When the impact of the power plant was assessed some 12 years ago, the plan was to pump the discharge water back deep into the ground, below the water flow to Myvatn. The water would also be thinned so much that it would not cause trouble if it did reach the lake. Since then much experience has been obtained with the discharge water in other power plants and there is a consensus that it does not work as it should. The groundwater flow is also not as well known as it should be, with two conflicting research reports. Our knowledge of the Lake Myvatn ecosystem has also improved greatly in those twelve years and we now know how vulnerable the lake is to small changes in its nutrient dynamics.