MYRTLE GROVE, La. (WGNO) —An alert went out Tuesday afternoon to residents in Plaquemines Parish after water samples began to present higher levels of sodium and chlorine in the Gulf of Mexico.

The New Orleans district of the Army Corps of Engineers says due to how low the river levels have dropped, salt water began to infuse with the fresh water of the gulf and ended up in the water supply to homes in the area.

An underwater levee in the Myrtle Grove in an effort to stop the flow of the salt water heading that way. According to the Corps of Engineers once in every 10 years, an underwater levee is built.

Reports reveal this is the lowest the river has been this low since 1988.

“We know that when the river is around 300,000 cubic feet per second, thats when it no longer has the power to keep the salt water out. Right now we are at about 180,000 cubic feet, so we have about half the power we need,”said Corps of Engineers Ricky Boyett.

It is not known how long the underwater levee will be in use but officials say it will take about two weeks to complete.

Until then, residents that suffer with high blood pressure and other health issues are encouraged to the watch their water.