Right before the extended Independence Day weekend, numerous beaches nationwide were closed due to high levels of harmful bacteria, accompanied by health advisories. The issue stems from fecal waste, a prevalent summer concern in both freshwater and ocean areas, which can lead to gastrointestinal illnesses and skin infections.

At least six states have enacted beach or lake closures and advisories. Testing revealed unsafe levels of fecal bacteria in various waterways. In Massachusetts, nearly 20 beaches are closed due to elevated bacterial counts. In New York, four beaches have been shut down. Illinois has issued at least eight advisories over recent weeks. Los Angeles County announced 8 ocean water quality advisories as of Tuesday. Three beaches in Michigan have been closed.

The bacteria posing threats to summer swimmers include E. coli and enterococcus. Contamination may result from sewage, fertilizers, or stormwater runoff. E. coli is often found in freshwater environments, while enterococcus can develop in both oceans and freshwater.

Edward Dudley, the director of Penn State’s E. coli reference center, noted that testing for swimming waters is a standard practice, as are the subsequent closures.

Antalpreet Jutla, an associate professor of environmental engineering science at the University of Florida, mentioned that beach closures tend to occur during the summer months when surface temperatures rise and bacteria can proliferate more easily. However, he emphasized that various factors — including human activities, temperature, and water movement — can influence bacterial growth.

Jutla also reiterated that closures due to fecal bacteria are quite common.

In North Carolina, authorities cautioned about a cyanobacteria algae bloom in Lake Norman, advising people to keep children and pets away from water that appears bright green, blue, or scummy. Unlike fecal bacteria, cyanobacteria are one of the primary causes of algae in freshwater environments, as noted by the Centers for Disease Control and Prevention. Research indicates that climate change may cause more frequent cyanobacteria blooms.

The Environmental Protection Agency has established guidelines for safe levels of fecal bacteria and recommends water quality and monitoring standards. Some Illinois beaches undergo testing every two weeks.

“Generally, the higher the level, the greater the risk,” Dudley stated.

Fecal waste can result in numerous harmful diseases, but experts are increasingly concerned about the recent rise in another dangerous bacterium, Vibrio.

Vibrio is a potentially lethal bacterium responsible for similar beach closures in the recent past. These carnivorous bacteria flourish in warm coastal waters. Jutla noted that he has observed Vibrio gradually migrating northward across the US. Testing for this bacterium varies based on specific conditions and concentration thresholds.

“While trends nationwide seem unusual at the moment, it’s something we’re particularly worried about: its presence in coastal waters,” Jutla remarked regarding Vibrio.

The deadly V. vulnificus is a rare type of bacterium, yet infections have surged in recent years due to warmer seawater along the US East Coast.