A polluted tailings pond at the Kennecott Utah mine has sunk 20 feet or more, raising concerns that it has seeped contamination into the neighboring Great Salt Lake. But the state regulator charged with protecting the lake’s water, the Division of Water Quality, allowed the mining company to edit this information out of a recent groundwater permit, documents show. The division also allowed Kennecott to quietly nix a study that would have investigated the tailing pond’s connectivity to and impact on the Great Salt Lake. … At issue is selenium, a mineral that can be toxic for humans at high concentrations. It also poses a threat to the millions of migrating birds that visit the Great Salt Lake every year. The material weakens eggs and deforms embryos. It can bioaccumulate in the wetland bugs those birds eat, and work its way up to hunters harvesting waterfowl.