Certain Salem residents are again being advised not to drink the tap water, after city officials said Wednesday they found low levels of cyanotoxins.

The advisory applies to children younger than 6; people on dialysis or with compromised immune systems; pregnant or nursing women; the elderly; and pets.

It also affects Salem, Turner, the Suburban East Salem Water District and Orchard Heights Water Association.

The advisory is a return of one that caused statewide concern and local panic last week. The previous advisory lasted for nearly five days, during which time Gov. Kate Brown issued a state of emergency so she could direct the Oregon National Guard to set up round-the-clock water distribution sites and empower the Oregon Attorney General Ellen Rosenblum to investigate reports of price gouging.

It was lifted Saturday.

The city requires two days of clean test results before it can lift an advisory, meaning the current one won't be lifted before Friday.

The cyanotoxins are released by blue-green algae blooms in Detroit Lake, the source of much of Salem's drinking water.

Lacey Goeres-Priest, the city's water quality supervisor, warned residents last week that her staff had seen another blue-green algae bloom forming, so even though the first advisory might be over, it could come back.

Algae blooms have become more common in Detroit Lake in the past decade. It is a relatively new problem to the Pacific Northwest, so officials have been sending samples by rush order from four water monitoring sites to a laboratory in Ohio. The toxin is more often found in the Midwest.

The city took considerable heat last week because officials waited four days before notifying the public of the cyanotoxins, and officials said they regret that. But they also said it wasn't a tactic to hide information or stall a backlash.

The U.S. Environmental Protection Agency says that vulnerable people can drink the affected water for 10 days before any symptoms are likely to show. As long as a city issues the advisory within that window, they are acting responsibly, according to the federal guidelines.

However, City Manager Steve Powers said last week that he would move more quickly to alert the public to any potential threats.

The city set up eight water distribution sites:

Wallace Marine Park, 200 Glen Creek Rd. NW, Salem

Oregon State Fairgrounds, 2330 17th St. NE, Salem

Bush's Pasture Park, Mission St. entrance, 600 Mission St. SE, Salem

Woodmansee Park, 4629 Sunnyside Rd. SE, Salem

Chemeketa Community College, Brown Parking Lot, 4000 Lancaster Drive NE, Salem

East Salem Suburban Water District, 3805 La Branch St. SE, Salem

City of Keizer Civic Center, 930 Chemawa Rd NE, Keizer

Former Chevrolet Dealership, 5325 Denver Street, Turner

All sites except East Salem Suburban Water District (open until 8 p.m.) will operate around the clock, officials said. All bulk water distribution locations are pull-through, residents must bring their own containers, and there is a 5-gallon limit per family. Residents in need of assistance are advised to call the Public Works Department at 503-588-6311.

For medical information, call 211.

The city also now posts water sampling information publicly. That can be found on its website or Facebook page.

-- Molly Harbarger

mharbarger@oregonian.com

503-294-5923

@MollyHarbarger