NEW ORLEANS (AP) — The Latest on the effect of freezing weather on water systems in Louisiana (all times local):

4:55 p.m.

The worst of the freezing weather is over in south Louisiana but the big thaw is posing problems, too.

Pipes damaged during two nights of unusually cold temperatures were thawing and leaking, leading to low water pressure in New Orleans and surrounding areas.

Gov. John Bel Edwards says about 170 inmates at the jail In St. John the Baptist Parish were moved to a state facility Thursday because of low water pressure.

Residents in New Orleans and several neighboring communities were asked to conserve water. And parts of New Orleans and neighboring Jefferson Parish were under boil-water advisories because pressure was so low it raised the possibility of contamination.

Schools in New Orleans and neighboring areas were to remain closed for a third day Friday.

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11 a.m.

The winter blast that brought unusually cold weather to south Louisiana is causing serious problems for some water systems, with officials in one parish calling on residents Thursday to immediately stop using tap water.

In St. John the Baptist Parish, west of New Orleans, authorities said water usage should stop until further notice — in hopes of replenishing the water supply before another cold night.

The main factor: freezing water causes pipes to rupture, leading to major losses of water.

In St. Charles Parish, New Orleans and Jefferson Parish, authorities asked residents to conserve water. At a joint news conference, New Orleans Mayor Mitch Landrieu and Jefferson Parish President Mike Yenni asked residents to delay using dish washers, clothes washers and to otherwise conserve water until a loss of water pressure caused by broken pipes could be remedied.

"Help relieve the pressure on the system by only using waster in situations where it's absolutely necessary," Landrieu said.

Authorities also issued boil water advisories for New Orleans and Jefferson Parish residents on the East Bank of the Mississippi River. Authorities say drops in pressure in those areas were serious enough to raise concerns about contamination entering the system.

Numerous breaks in pipes were evident on properties around the city during a brief thaw Wednesday. A full assessment of the damage in the New Orleans area won't be possible until pipes that froze again overnight thaw out. No more hard freezes are in the forecast.

Other complications caused by the low water pressure: Yenni said some surgeries were canceled at Jefferson Parish hospitals because of water issues. And officials reported that portable toilets and hand sanitizer were being provided at Louis Armstrong International Airport because water pressure to public restrooms was low.