In the wake of the heavy rain on Wednesday, eight beaches in Quincy and one in Braintree have been closed to swimming because of bacteria contamination.

Avalon, Chickatabot, Heron, Delano (Back), Broady (Baker), Germantown Fire Station, Orchard and Nickerson beaches in Quincy and Smith Beach in Braintree are over the limit for bacteria.

Avalon Beach has 30 times the contamination considered safe. Broady, Germantown and Orchard are more then 18 times over the limit.

The bacteria levels at Smith Beach are twice as high as recommended for swimming.

The water is being retested and results will be available Friday afternoon.

All other beaches on the South Shore are open.

See water quality test results for each community and for Cape Cod, the South Coast and North Shore.

For more on Quincy beaches, call 617-376-1288, or visit tinyurl.com/ledger-quincy-beaches. For more on Wollaston Beach, call 617-626-4972.

Seventy-five salt water beaches on the South Shore are tested for enterococci, intestinal bacteria found in humans and animals. High levels of enterococci indicate the waters may also contain other disease-causing microbes that are present in sewage but are more difficult to detect. Bacterial colonies are filtered from three ounces of water and placed on a gel infused with nutrients and chemicals designed to promote growth. Left in an incubator, the single cells isolated on the filter grow explosively, forming colonies visible to the naked eye.After one day, the colonies are counted and if they exceed 104 colonies, the beach is closed to swimming.

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8 beaches in Quincy, 1 in Braintree closed