Officials in Louisiana are in a race against time as salt water from the Gulf of Mexico threatens drinking water supplies in New Orleans and its surrounding areas because of unusually low levels in the drought-addled Mississippi River.

New Orleans Mayor LaToya Cantrell signed an emergency declaration Friday in response to concerns that salt water encroaching upriver could affect the availability of safe drinking water in the coming weeks.

The situation highlights the dangers of saltwater intrusion for communities in the southeastern part of Louisiana and adds to broader concerns about climate change and the availability of safe drinking water in drought-prone parts of the country.