Ascension Parish officials issued a boil water advisory Thursday night in part of a public water system on the west bank of the parish after pressure dropped below levels that would ensure disinfection.

This is a different water system than the one run by the private Peoples Water Service Co., which operates in Donaldsonville and recently was ordered to check its water treatment by the state.

Lester Kenyon, parish government spokesman, said the warning, which went out by telephone starting at 8 p.m., remained in effect Friday afternoon for the eastern section of the Ascension Consolidated Utilities District No. 1 water system outside Donaldsonville.

Residents in the Lemannville community and some businesses on La. 70 and La. 3089 are affected.

Kenyon said water pressure on the section of district’s system supplied by St. James Parish dropped below required levels, prompting the boil order. The order protects against the chance of a loss in disinfection levels due to the low pressure.

St. James Parish lost pressure after St. John the Baptist Parish officials flushed lines in the Lake des Allemands community of Pleasant Blend, said Brandon Keller, St. James Parish government spokesman.

St. James Parish serves the Pleasant Bend area, southeast of Donaldsonville, on the same line that serves Lemannville and some of the Donaldsonville area in Ascension. The Ascension area is at the end of the St. James line.

Keller said the flush, combined with the usual spike in evening usage, drew down St. James’ water tower and led to the drop in pressure in Ascension.

Kenyon, the Ascension government spokesman, added that the affected residents on that part of the utilities district network are getting water, but pressure was still low Friday.

The water-quality issue with the parish water system in the Donaldsonville area comes after Peoples Water Service Co., the private utility that serves the city and some areas outside it, has run into trouble with the state Department of Health and Hospitals over the possibility of water quality concerns.

Since September, internal company tests showed water in Peoples Water’s treatment plant had levels of the disinfectant chlorine dioxide well above federal standards and didn’t report that to DHH or the public, as required.

The water reached levels prompting DHH to order young children and pregnant women, and later the entire customer base, not to drink from the tap for nearly four days while Peoples Water changed its disinfection methods. The company has maintained the tests were inaccurate and that customers on its distribution network never received water with high levels of chlorine dioxide.

DHH later ruled, after testing water in the network, that the water was determined safe to drink.