In response, Mr. Neyelle told me the water-heart story, about a Sahtuto’ine ancestor who lived around Great Bear Lake, in an area called Caribou Point. One day the fisherman set out four hooks. When the fisherman returned to check on them, a lake trout had broken one of the lines and taken the hook. This bothered the fisherman, because in those days, hooks were extremely valuable. So that night, he transformed himself into a losch, also known as burbot, a freshwater version of cod. The fisherman swam down to the middle of the lake to look for the hook and heard a booming sound. There, at the bottom, he saw a gigantic beating heart. All the species of fish — trout, whitefish, pickerel, herring, suckers — faced the heart, surrounding and protecting it. He swam back to shore after seeing this, and the following morning when he went to check on his three hooks, he found three trout. One of them had the hook he had lost the day before dangling from its mouth.

When the fisherman saw the water-heart, he realized Great Bear Lake was alive, Mr. Neyelle said. “The lake gives life to the universal: grass, insects, willow, everything.” Some in Deline believe that the water-heart at the bottom of the lake gives life to all of the lakes, oceans and rivers in the world. For the Sahtuto’ine, this belief underscores not only why Great Bear Lake must be protected, but also why its protection is of global importance.

Toward the end of our conversation, Mr. Neyelle also mentioned Eht’se Ayah’s prophecy. “When there is no food or water all around the world, many will come to Great Bear Lake,” he said. “It will be one of the last places that has both.” No matter how many times I heard this apocalyptic prediction, it was jarring to hear, especially when inserted into conversations about Great Bear Lake’s beauty and providence.

The regular evocation of this prophecy reminded me of what happened on the other side of the lake in the 1940s, in Port Radium. The site of a large uranium ore mine, it was the most significant industrial development in Great Bear Lake’s history. During World War II, uranium from Port Radium was sent to the United States for the war effort, where it provided much of the material for the Manhattan Project and the atomic bombs that fell on Hiroshima and Nagasaki. Although it stopped producing uranium in 1960 and is now abandoned, Port Radium was at its peak larger than Deline.