PACIFICA (CBS 5/BCN) – Unsafe levels of bacteria detected at four beaches in San Mateo County this week have prompted health officials to order temporary closures.

Heavy rain over the weekend caused sewer pipes to overflow and push wastewater into the ocean near Pacifica and the Bay near San Mateo, according to the San Mateo County Health System.

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Weekly tests conducted at ocean beaches and bay lagoons revealed unsafe contamination levels of E. coli or coliform bacteria in the near-shore waters, prompting closures at Linda Mar Beach, Rockaway Beach, Lakeshore Park, and Aquatic Park.

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Surfers, swimmers or anyone coming into contact with the water at the closed beaches is at risk of getting sick, officials said.

Rockaway Beach reopened on Tuesday. The other three beaches will be reopened when future testing shows bacteria levels have returned to levels safe enough for recreational contact.

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