Some beaches in Avalon, Wildwood Crest, Cape May, Sea Isle under advisory for bacteria

The New Jersey Department of Environmental protection is reporting that certain beaches in Avalon, Wildwood Crest, Cape May, Sea Isle have been placed under advisory for high bacterial counts, but are still open.

The beaches are all in Cape May County:

The recreational beaches are under advisory because water samples exceeded 104 colonies of enterococci bacteria per 100 milliliters. Enterococci, a measure of fecal pollution, are a type of bacteria found in animal and human waste and are measured as indicator of possible poor swimming water quality.

The New Jersey Department of Health samples water quality at 180 ocean stations and 35 bay stations along the coast. When a sample exceeds the standard, the DEP issues a swimming advisory, a warning that water conditions may be unhealthy.

If two consecutive daily samples exceed the standard, the beach is closed until sample counts fall back below the standards.

» READ MORE: How safe is it to swim at the Jersey Shore?

A number of factors can elevate bacteria levels. Especially after heavy rains -- and we’ve had plenty of that lately -- older sewer systems are prone to overflow, releasing untreated sewage into the water. Wildlife waste also can wash into the water. Altogether, the pollution can be hazardous to humans and also kill fish and wildlife.

However, the DEP did not say what caused the spike leading to the advisories, which it lists at njbeaches.org.