VICTORIA - A failed classroom experiment four years ago in northwestern British Columbia has spawned widespread concern from parents who fear their children face risks of lead poisoning from drinking water at their schools.

A science class in Kitimat was trying to raise salmon eggs in an aquarium in 2012 but the eggs kept dying, prompting water tests that found copper and lead, said a B.C. Centre for Disease Control report released Thursday by the Opposition New Democrats.

“Here, the death of the salmon eggs in a classroom aquarium triggered an investigation that found elevated levels of copper and lead in the school's drinking water,” said the report, dated April 2014.

A district-wide investigation then found varied levels of lead and copper in drinking water in other schools.

Flushing school water taps every morning was deemed a cheap and effective means of keeping the water safe, read the report, which suggested these mitigation actions “may be informative for health authorities across Canada.”

But North Coast New Democrat MLA Jennifer Rice said Thursday it took four years for the investigation's results to filter to Prince Rupert, located about 200 kilometres from Kitimat.

Earlier this week, students received a note from the local school district that elevated levels of lead were found in the drinking water at four schools in Prince Rupert.

“Parents are scared,” said Rice. “Parents are wondering if they should be testing their children for lead poisoning.”

The Feb. 16 letter stated: “School District 52 is working with Northern Health to address elevated levels of lead detected in water at four schools in Prince Rupert. The school district is committed to ensuring that the drinking water provided to staff and students at local schools is safe and has taken steps to address possible health concerns related to exposure of lead, including the implementation of a flushing program before the start of each school day.”

Exposure to elevated levels of copper is linked to acute gastrointestinal effects in the short term and possible liver effects in the long term, while even low-level lead exposure is associated with neurodevelopmental effects, said the centre for disease control report.

Rice said she's concerned Prince Rupert residents only learned this week about a problem discovered four years ago.

“It has been four years since the situation in Kitimat, which was identified at that time as a possible similar situation in other northwest communities,” she said. “Four years is too long. They waited four years to even test Prince Rupert.”

Health Minister Terry Lake said the government is aware of the issue in Prince Rupert and is taking action. School water lines are being flushed every morning and filters are being installed on water fountains, he said.

Provincial medical health officer Perry Kendall said he's not sure why broader warnings about school water quality were not issued following the Kitimat issue.

He said school water systems in southern B.C. schools were tested for lead levels during the 1980s and 1990s, but the program “apparently” did not extend to the north.

“Ideally, it would have happened earlier,” said Kendall. “I don't know why it didn't.”

Kendall said lead exposure for children is harmful, but blood tests taken from children over a two-year period from 2009-2011 did not find elevated lead levels.

“From what we can see from the previous testing that was done in areas where kids were drinking water with higher levels of lead, we're not seeing higher levels of lead in those children.”

He said the situation is Prince Rupert is “not an acute health problem.”