CHARLESTON, S.C. (WCBD)- Pollution in Charleston’s waterways is not just an issue when the city floods.

Experts say that after storms, rainfall can hurt local waterways without a flood event.

“So the more it’s been raining the worse local water quality is,” said Andrew Wunderly, the Executive Director of Charleston Waterkeeper.

The storm water takes pollutants, such as trash and fertilizer, from the ground as it flows into the nearest body of water.

“Bacteria, dog waste, pet waste, wildlife waste, septic tank drain fields, sewer overloads. It can be pesticides, herbicides,” said Wunderly.

Data collected by Charleston Waterkeeper over a nine year period shows that water quality is linked to rainfall amounts.

Wunderly and Charleston Waterkeeper keep track of whether or not a waterway meets the standard for safe water recreation. 104 colony forming units of bacteria per 100 milliliters of water is the safe level for swimming and other activities

“After a rainstorm we might find levels that are ten and in some cases as many as 20 times that standard for safe recreation,” said Wunderly.

Those levels can stick around in your local creek or river for two days after it rains. Which means Wunderly discourages swimming during that time.

“If you do choose to swim, wash up, try to keep the water out of your ears, eyes, nose, throat that sort of thing,” said Wunderly.

The City of Charleston says that they have rules in place to make sure any new development or redevelopment has measures to address water quality.

“The most common ones you’re going to see are storm water ponds where there’s a chance to let those contaminants settle out in the pond. Clean water is taken off of the top of the pond out into a marsh or creek or canal in the area,” said Matthew Fountain, Director of Stormwater Management for the City of Charleston.

The city is using these measures at The Battery on an ongoing project.

“On the low Battery work we are doing we’re retrofitting the existing storm water system with these water quality structures to help filter out the water and clean it before it enters the harbor,” said Fountain.

He says that homeowners can help as well.

“Simple things you don’t even think about like picking up your pet waste even when it’s in your own backyard and throwing it in the trashcan,” said Fountain. “If you have a septic system making sure you’re getting it maintained and cleaned every so often.”