Environment New York, a research and policy center, is calling on state and local officials to take steps to prevent pollution at local beaches. The group recently released a report on their findings about 336 beaches that were tested across the state.

The report showed 59% of the beaches tested were found to have potentially unsafe levels of fecal bacteria on at least one testing day. Another 10% were found to have potentially unsafe levels on at least a quarter of the days tested.

The main causes for this, according to the report, are overflow from outdated sewage systems and runoff from new developments.

“Different localities are doing very different amounts of testing and we want to make sure that on any day, it’s safe to swim,” said David Masur, senior advisor with Environment New York. “Really, we’re doing the highest level of testing possible to ensure that.”

Advocates say governments can prevent polluted water by investing in wastewater infrastructure and expanding testing across the state.