Atitlan is indeed breathtaking, but nowadays it is leaving many visitors gasping for breath. A thick brown sludge is tarnishing its once blue waters. It is the result of decades of ecological imbalance, brought on by economic and demographic pressures. The unsightly and smelly layer, more than 100 feet deep in some areas, is chasing tourists away from Mayan towns in the area and posing huge cleanup expenses to a government already strapped for cash. Worse, the results of a University of California, Davis, analysis found that the bacteria is toxic. Scientists are urging residents to avoid cooking with, bathing in or drinking the water. Several towns get drinking water from the lake.