Fun fact #1: Arsenic, mercury and silenium are all commonly present in geothermal brine (I think it's relatively low for Svartsengi/blue lagoon though...never been but I work for the other geothermal capital New Zealand). Fun fact #2 Lake Anna Virginia is the manmade lake which is the intake/outfall for North Anna nuclear power plant is one of the most popular recreational lakes in the state.