QUINCY, Mass.

Beaches in Quincy, Braintree, Hull and Marshfield have been closed to swimming after testing showed elevated bacteria levels.

The Patriot Ledger reports the Milton Street section of Wollaston Beach, Darcys and Newport beaches in Hull, Smiths Beach in Braintree and Green Harbor Beach in Marshfield are all over the limit recommended for swimming.

Milton Street was posted Wednesday and the others on Thursday.

Newport Avenue in Hull is four times over the limit and Smiths Beach is double. The other three are under twice the recommended maximum.

In most cases the culprit is rain that washed contamination into the water. The beaches are being retested and results are expected on Friday.

The other 60 salt-water beaches on the South Shore passed bacteria tests this week and are open for swimming.

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 tpl-beaches. For more on Wollaston Beach, call 617-626-4972.

HOW BEACHES ARE TESTED

Sixty-five beaches on the South Shore are tested for intestinal bacteria found in humans and animals.

High levels indicate the possible presence of 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.

If the past five samples have a mean exceeding 35 colonies, the beach must also be closed to swimming.

See the rest here:

Five beaches closed due to water contamination - WCVB Boston - WCVB Boston