Troubling reports about dead fish, algae blooms and discoloured water have led health officials to close down a popular Fraser Valley lake to swimmers.

Pictures posted to social media this week purportedly show some of the dead fish floating in Hatzic Lake, a swimming and water-skiing destination located on the north side of the Fraser River near Mission.

On Tuesday, Fraser Health announced that it has closed down the lake as it investigates what’s happening.

"Residents and visitors should avoid contact with water at Hatzic Lake until test results become available," the health authority said in a news release.

Fraser Health said people who have recently been swimming or taking part in recreational activities at the lake have reported feeling nausea, stomach cramps, itchy skin or irritated eyes. Social media users said children and dogs have experienced “burning” in their eyes.

B.C.'s Ministry of Environment and the federal Department of Fisheries and Oceans have also been alerted about the issues and are investigating.