What’s that doing there?

The Great Salt Lake is full of more than just salt—it’s also chock-full of mercury, scientists discovered three years ago. Now, the Environmental Protection Agency and the state of Utah are beginning the lengthy (and expensive) process of figuring out just how much mercury is in there, and how it came to be.

MSNBC reports that the lake, which was, during the last ice age, a vast inland ocean, may have been polluted by man-made industry, or it could be a natural phenomenon. In either case, mercury is known to cause illness in birds and other animals, though Salt Lake birds found to have high levels of mercury show no symptoms.

The study will likely take a couple of years, and the first phase is estimated to cost $280,000.