sewage spill
© Dean Musgrove/The Orange County Register, via Associated PressFILE: The release of millions of gallons of untreated sewage into the Dominguez Channel in Carson, Calif., forced the closure of some beaches on Friday.
Beaches in several states across the country have been closed to swimmers over the last few days due to harmful levels of bacteria in the water, NBC New York reported.

In Massachusetts, at least 37 beaches were closed as of Monday afternoon due to "bacterial exceedance," according to the state's Department of Public Health (MDPH). Many of the beaches tested positive for high levels of a type of fecal bacteria, and beachgoers were warned not to swim or enter the water in those locations to avoid risk of illness, according to the health agency.

Additionally, at least three beaches in Coronado, California - located on a peninsula in San Diego Bay - have been closed since June 26 because "[b]acteria levels exceed health standards." San Diego County's Department of Environmental Health and Quality said such closures are usually due to sewage or chemical spills.

Further, New York's Suffolk County last week issued an advisory against bathing at 63 beaches due to increased bacteria levels caused by heavy rainfall and stormwater runoff.

Although health officials did not elaborate on what types of bacteria were found in California or New York, officials in Massachusetts identified the bacteria as enterococci. The bacteria are typically found in the intestinal tracts of warm-blooded animals, including humans, according to the U.S. Environmental Protection Agency (EPA), and may "indicate possible contamination of streams and rivers by fecal waste."

Enterococci bacteria commonly cause urinary tract infections, and can also cause blood infections and endocarditis, an inflammation of the lining of the heart's values and chambers, according to the National Institutes of Health.

Heavy rains after long periods of drought can pick up animal or human excrement, which can then be carried by runoff into nearby bodies of water, including oceans. Heavy rains can also cause sewage systems to overflow, causing untreated sewage to likewise contaminate bodies of water.