HOW STORMWATER POLLUTION IMPACTS OUR HEALTH AND SEAFOOD

BY LUCERO SANCHEZ

While most of us are familiar with elevated levels of mercury and other heavy metals in some fish species, more studies have found the presence of other toxic pollutants in our seafood. New and emerging research shows the prevalence of PCBs, PFAs, POPs, microplastics, and more. This new alphabet soup of acronyms might have you wondering how our seafood is becoming riddled with toxins and whether there is any way to prevent it.

The fact is, seafood quality and availability are affected by the health of watersheds. At San Diego Coastkeeper we like to say, “If you’re not in the water, you’re in a watershed.”

A watershed is an area of land draining into a common body of water. The mountains, canyons, and valleys act as a funnel, shedding water to the lowest point in a watershed. Some watersheds drain into a river, lake, estuary, or bay, while others drain into the ocean. You can think of your bathtub as a smallscale model of a watershed and a drain sewer as the common water body. In San Diego, we have 11 watersheds that all drain to the Pacific Ocean.

Pollution Threatens All Life

Stormwater pollution is San Diego’s most persistent threat to our marine ecosystems.

Living in cities like San Diego means that large portions of our watersheds are highly urbanized, which can lead to issues when it rains. City streets have impervious surfaces like buildings, parking lots, and roads that block water from soaking into the ground. When stormwater or urban runoff flows over hard surfaces like roofs, asphalt, and sidewalks, it picks up trash, debris, and chemicals such as fertilizers and pesticides along the way, eroding landscapes and creating public safety concerns.

In San Diego, we built most of our stormwater infrastructure almost 100 years ago to move water away from the city as quickly as possible to prevent flooding and property damage. Water running through this network of storm drains and outfall pipes is untreated, meaning pollution flows off our streets and onto our beaches.

After it rains, the fecal indicator bacteria levels off our coast consistently exceed public health standards. In Southern California, many are familiar with the 72-hour rule, a guideline that discourages people from entering the water for at least 72 hours, or three days, after it rains to avoid getting sick from contamination. While San Diegans can try to avoid entering the ocean during this time frame, sea life doesn’t have that option.

Seafood Dead Zones

Pollutants can wreak havoc on the natural balance of marine ecosystems. Increased nutrients can lead to harmful algal blooms, like the red tides we see here in San Diego. When nutrients like those found in fertilizers are higher than average in a water body, eutrophication sets off a chain of events that can lead to dead zones and massive fish kills. The abundance of nutrients causes an excess of plant and algae growth (or blooms), starving the surrounding waters of oxygen the fish and seagrass populations need.

Ocean Acidification

When the overabundance of algae and plants begins to decompose, this produces a lot of carbon dioxide. Excessive CO2 lowers the pH of seawater, a process known as ocean acidification. The National Oceanic and Atmospheric Administration calls ocean acidification the “osteoporosis of the sea,” a process made worse by rising temperatures and added toxins. Studies show that lower pH results in less carbonate, an essential mineral used by sea life to build shells and skeletons. This reduces catch for local commercial and recreational fisheries, meaning smaller harvests and more expensive seafood.

Toxic Bioaccumulation in Fish

Bioaccumulation is the buildup of toxic chemicals, like copper and zinc (compounds used in car brake pads and tires), in living tissue over time. It occurs when organisms, like fish, take in harmful substances faster than their bodies can break them down and eliminate them.

Consuming fish on the lower end of the food chain (also called trophic levels), such as anchovies, sardines, and herring, can help minimize our exposure to chemical contaminants. The higher up the food chain we go, the larger and longer-lived those species become, and the more accumulated pollutants like DDT and mercury are in fish like tuna.

For example, if you’ve fished at any popular spots along San Diego Bay, as with other public fishing places throughout the state you’ve likely seen warning signs listing potential health concerns related to eating the fish in the area.

For updates on fish advisories throughout the state, visit Good Catch California, a program created by the California Office of Environmental Health Hazard Assessment (OEHHA).

Improving Watershed Health Improves Seafood Supply

By protecting our watershed, reducing pollution, and fighting climate change, we can ensure safe and sustainable seafood for all. It all starts with us. As individuals, we can conserve water, reduce waste, wash our cars at a car-washing facility, install rain barrels and catchment basins, and plant native species gardens at home. On a larger scale, community members need to vote for candidates who support clean water initiatives and participate in public discourse to pressure companies and governments to take the necessary steps to protect water quality for everyone.

One small way to take action is to sign up for newsletters of organizations already engaged in this work. San Diego Coastkeeper’s newsletter includes calls to action, blogs, important news, and more.

Together we can protect the future of seafood.

» sdcoastkeeper.org/newsletter