More than half of the nation’s waterways are polluted with toxins like mercury and have been stripped of vegetation that protects them, according to a stark new report from the EPA.

The first comprehensive survey looking the health of thousands of stream and river miles across the country found that 55 percent are in poor condition for aquatic life.

Office of Water Acting Assistant Administrator Nancy Stoner said the science shows that the country’s streams and rivers are under “significant pressure.”