Iliamna Lake, home to the United States' only population of freshwater seals, is Alaska's deepest and most massive body of freshwater, located some 200 miles southwest of Anchorage. Among its many mysteries, the lake is reputed to harbor the fabled “Illie,” a huge, white lake monster said to “bite holes in natives' bidarkas” (canoes). Iliamna Lake's clear, pristine waters provide important spawning habitat for the largest sockeye salmon runs in the world; brown bear, moose, wolverine and other wildlife far outnumber human residents. Given the remoteness of the area, it's not entirely surprising that the seals of Iliamna Lake are little known and sometimes confused with folklore.

Alaska natives, who have hunted small numbers of Iliamna Lake seals for centuries, describe the seals as fatter, larger and darker in color than saltwater seals, with a unique fur pattern. When processed for fur and meat, these seals are also described as “oilier,” possibly due to a diet rich in salmon.

Scientists know little about the Iliamna Lake seal, but the most recent information suggests that the seals are most likely a distinct population segment of Pacific harbor seals. Scientists do not know exactly how many seals live in the lake or where the seals spend the winter. Further research needs to be conducted to discover the seals' annual movements, population numbers, habitat use, diet and behavioral patterns.

The Center for Biological Diversity filed a petition on November 19, 2012 to protect these unique and mysterious seals under the Endangered Species Act. In May 2013, the  federal government announced that the seals may need protection. 

Although much about the Iliamna Lake seal remains a mystery, there is no confusion on the fact that this seal faces serious and growing threats to its survival from large-scale mining operations and from climate change.

Pebble Project, a massive copper and gold mine proposed for the Iliamna Lake area, would destroy the pristine waters of the lake and fill in and pollute the rivers and streams that feed into it. Pebble Project would also build a road along the lakeshore, right next to the islands and streams where Iliamna Lake seals haul out, raise their pups and hunt for fish. Disturbance from the massive vehicles travelling the road, runoff and dust from traffic, and increased human presence in the area would all have an impact on Iliamna Lake seals.

Pebble Project would also have major impacts on Iliamna Lake's huge salmon runs. Salmon are critical both as part of the Iliamna Lake seal's diet and as a mainstay of the entire lake ecosystem. Freshwater fish, small invertebrates and plant life would also be affected; without any available prey, Iliamna Lake seals would starve.

Climate change will also affect salmon and result in increased water runoff, warmer water temperatures, greater water flows and increased siltation in the streams and rivers in which salmon spawn and lay their eggs. Young salmon fry and salmon eggs may be washed downstream before maturing, while conditions suitable for salmon spawning may cease to exist.

Climate change will also decrease the quality of Iliamna Lake seals' habitat. A rise in water level during the summer may cover up important dry-land haul-out sites for seals; changes in ice thickness and timing of ice cover may hurt their winter habitat. Climate change could also affect the timing of salmon runs, so that Iliamna Lake seals have little food during the most energetically demanding moments in their life cycle.