A new map designed by Stony Brook University and the Nature Conservancy outlines the threats faced by Long Island waterways.

Areas on the map show where "rust tide" and "brown tide" have occurred.

The map also shows where algae levels have grown toxic to fish and people. The shellfish beds where the toxic levels were found, in Northport Harbor and Huntington Harbor, have been closed by the Department of Environmental Conservation.

Scientists say the increased problems come from cesspools and septic tanks that leak nitrogen into the water, which the algae feed on.