Urban Runoff

Urban runoff carries pollution to our beaches and ocean. In particular, urban runoff can carry bacteria to our local rivers and creeks, and to our oceans. Swimming in water that’s been contaminated by bacteria means that you can contract a skin rash, or a respiratory or stomach infection. Here in LA, the County Health Department monitors public beaches on a regular basis and will post warnings if bacteria counts are high. In general, it is a good idea to stay out of the water several days after a rainstorm. Also, never swim near a flowing stormdrain (or anywhere you see water crossing the beach from inland), and follow any posted Health Department recommendations.

Certain contaminates, like mercury, can build up throughout the food chain (they can get ingested by filter feeders, which are eaten by small fish, that are then eaten by larger fish) and ultimately result in unsafe levels of pollutants in many different species, some of which are then eaten by people.

Urban runoff also contains a variety of other pollutants including sediment, oil and grease, metals and other toxins. All of these pollutants can severely impact freshwater and marine habitats. Toxic metals are a major problem in many rivers and bays in the Los Angeles area. These toxins are found in the water column and accumulate in sediments where some types of organisms feed. High volumes of sediment (like mud, sand or dirt) transported by urban runoff can also impact habitats. Certain organisms are unable to reproduce in areas with large amounts of fine sediment.

Sewage

When raw or improperly treated sewage is discharged into the ocean, or spilled near a beach, swimmers can contract serious illnesses. Commonly, people who swim or surf in sewage contaminated water can come down with skin rashes, sinus, ear and throat infections, and stomach flus. Swimmers can even contract hepatitis from sewage-contaminated water. In LA, sewage spills must be reported to the health department, and posted on the beach. Also, spills must be announced to the media and to watchdog organizations like Heal the Bay.

Marine life also suffers from sewage discharged into the sea. Bottom dwelling fish, like halibut and croaker develop skin lesions, tumors and other problems. Even highly mobile animals, like dolphins, develop skin problems when exposed to concentrated, untreated sewage. Other animals choose to leave habitats that are impaired by sewage in search for cleaner waters. Before sewage treatment was improved at Hyperion, our local sewage treatment plant, dolphins were rarely seen in the Santa Monica Bay. Now, with improved sewage treatment, it is not uncommon to see pods of dolphins swimming along our shoreline.

Marine Debris

Some trash on beaches and in shallow water, like syringes, glass, and other sharp objects can be dangerous to beach-goers. Plastic trash at sea is also known to absorb chemicals such as PCBs and DDE which may become a potential source of toxins to marine life that ingests this trash. Since small bits of plastic are often ingested by filter-feeding organisms at the bottom of marine food webs, these toxins may pass through the food web, and possibly have implications for human health. When trash, like plastic bags and balloons, ends up in the ocean, turtles, fish, birds and other marine life mistake it for food, like fish eggs, other types of plankton and sea jellies. If they eat enough plastic, their stomachs can fill up, tricking them into feeling full. The animals stop eating when they think they’re full and can starve to death—even when they’re surrounded by food.

Animals can also get tangled up in trash like six-pack rings, ribbons and fishing line, which makes it hard to swim, fly, and eat. Imagine how it would feel to be trapped in trash. To find out, place a rubber band on your thumb and pull it over the back of your left hand across your knuckles and on your pinky finger. Now, using your left hand try getting the rubber band off your hand. You can only use that hand, no teeth and no help from the right hand. Were you able to get untangled?

Trash floating at sea can carry organisms including small crustaceans, barnacles and plankton. Sometimes rafts of trash form that can actually support larger animals. When organisms from one part of the world are transported to another region by this floating debris, problems can occur. The invading organisms may not have predators in their new home, and may outcompete local organisms for food and habitat. Little is known about how much marine debris contributes to the transportation of invasive species.