Baton Rouge, La. - Officials with the Louisiana Department of Health announced today that they are monitoring certain public drinking water systems to determine if they have residual chlorine levels of 0.5 milligrams per liter throughout their distribution lines. For drinking water systems that utilize chloramines, the Department is also strongly recommending they increase the frequency of testing and number of samples for chlorine residual levels throughout their distribution lines.

Residual chlorine levels of 0.5 milligrams per liter throughout drinking water distribution lines are key to eliminating biological contaminants such as Naegleria fowleri, the brain-eating ameba found to be present in two water systems in St. Bernard and DeSoto parishes. If systems do not meet the 0.5 threshold, the Department will require it. This requirement will exceed the current federal standard issued by the U.S. Environmental Protection Agency.

Based on LDH's analysis, the St. Bernard and DeSoto water systems have a common trait in that they disinfect by chloramination. A total of 84 water systems - including St. Bernard and DeSoto - disinfect by chloramination.

LDH public health engineers and officials will work closely with water systems and parish management teams to outline work plans and timelines in order to achieve required chlorination residuals. LDH will continue to evaluate chlorine residual levels in other public drinking water systems throughout the state; later requirements may be issued for systems that utilize free chlorine.

The 84 chloraminated water systems required to increase their chlorine sampling and monitoring frequency will be provided additional assistance by LDH that could include testing kits and personnel to conduct monitoring. Public health engineers are currently evaluating and monitoring recent residual chlorine levels for the more than 1,300 drinking water systems throughout the state.

LDH announced Tuesday that the U.S. Centers for Disease Control confirmed five positive test results for the presence of Naegleria fowleri in the DeSoto Parish Water Works District No. 1. The Department contacted parish officials and water system management the same day to set an aggressive plan to eliminate the ameba in the distribution system. Water Works District No. 1 began a chlorine burn Wednesday morning; the additional free chlorine in the system should kill any remaining ameba in the distribution lines. The chlorine burn will last for 60 days past the point at which the system reaches 1.0 milligrams per liter. At that point, LDH and the CDC will conduct additional testing for the ameba.

Wednesday, experts at LDH, and the Governor's Office of Homeland Security and Emergency Preparedness spoke with parish officials and water system management teams throughout the state in order to provide guidance on chlorination levels that are needed to kill amebas. Only two parishes have had positive test results for Naegleria fowleri; water systems in these parishes were tested in response to recent deaths from the ameba -- one each in DeSoto and St. Bernard parishes and a recent death in St. Bernard Parish in July.