More than four dozen beaches were declared unsafe for swimming on Monday as several destination coastlines in the North Shore began to reopen two weeks after a sewer rupture in Haverhill caused 8 million gallons a day of untreated wastewater to flow into the Merrimack River.
Plum Island and Salisbury beaches were among those reopened over the weekend. But 50 beaches remained closed ahead of another bout of extreme heat set to build over the region early this week.
The National Weather Service on Monday issued a Heat Advisory for most of Massachusetts starting Tuesday at 11 a.m. and running through Wednesday at 8 p.m., with temperatures forecast to challenge 100 degrees with high humidity and a heat index of up to 102.
The bacteria used as indicator organisms to test the waters at beaches are Enterococci and E. coli. Marine beaches are tested for the presence of Enterococci. Freshwater beaches are tested either for the presence of E. coli or Enterococci. Enteric bacteria are indicator organisms found in the intestines of warm-blooded animals and humans, often associated with fecal contamination.
An elevated presence of these organisms indicates the water may not be safe for human or animal consumption or contact, and may cause symptoms ranging from gastrointestinal pain to eye and ear discomfort to flu-like symptoms.
Most of these symptoms are minor, but occasionally a more serious illness may occur. Children, the elderly, and those with weakened immune systems are at greater risk of developing serious symptoms.
Some beach areas may remain open for recreational activities, though any contact with the water is strongly discouraged.
Massachusetts beaches closed as of 10 a.m. on Monday included:
See Latest Forecast (National Weather Service):
Monday
Sunny, with a high near 89. Southwest wind 7 to 11 mph.
Monday Night
Partly cloudy, with a low around 71. Southwest wind 9 to 11 mph.
Tuesday
Mostly sunny and hot, with a high near 97. Heat index values as high as 102. Southwest wind 8 to 15 mph.
Tuesday Night
Mostly clear, with a low around 80. West wind 9 to 13 mph, with gusts as high as 23 mph.
Wednesday
Mostly sunny and hot, with a high near 96. Northwest wind 9 to 11 mph.
Wednesday Night
Partly cloudy, with a low around 72. West wind 3 to 6 mph.
Thursday
Sunny and hot, with a high near 93. West wind 5 to 13 mph.
Thursday Night
Mostly clear, with a low around 69. Northwest wind 6 to 9 mph.
Friday
Sunny, with a high near 86. Northwest wind 7 to 9 mph.
Friday Night
Mostly clear, with a low around 67. Northwest wind 3 to 6 mph.
Saturday
Mostly sunny, with a high near 82. Light and variable wind becoming southeast 5 to 9 mph in the afternoon.
Saturday Night
A chance of showers. Mostly cloudy, with a low around 68. Southwest wind 6 to 8 mph. Chance of precipitation is 40%.
Sunday
A chance of showers. Partly sunny, with a high near 84. South wind 7 to 10 mph. Chance of precipitation is 40%.
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