We hear a lot about the sources of “water pollution” in the Bay Area and beyond—whether it’s pesticides and fertilizers from lawns and farmland coming down the creek, an industrial site spilling chemicals into the bay or ocean, or older vehicles that leak motor oil and other fluids onto the street—the potential for pollution is everywhere. But what chemicals are we actually talking about when we talk about “stormwater pollution,” and how might they affect us? These are the questions that often remain a mystery. Keep reading to find answers as we explain which pollutants are most common and hazardous to the Bay, how they got there, and what we’re going to do about it.
1) Mercury. It’s a planet, it’s what makes that old thermometer work, and it can also be found in that beautiful piece of striped bass you just bought at Whole Foods (and many other large-species fish for that matter).
While the Bay is slowly cleaning itself and washing an estimated 3,100 pounds of mercury a year out to sea, roughly 2,000 pounds of mercury enter the SF Bay each year from stormwater and other sources. At this speed, it will take generations for the bay to purge itself fully.
Depending on the weather, mercury can be transported from just a few feet away to halfway around the globe — today it mostly comes from the emissions of local oil refineries, cement kilns, coal burning power plants and forest fires. Once it lands in our waterways, bacteria convert it to methylmercury which is taken up by plants and then moves into the organisms that eat them. As it travels up the food chain its concentration in individual animals increases in a process called “biomagnification.”
Why should seafood lovers be wary of the presence of mercury in different kinds of fish? Because mercury is toxic in tiny concentrations! A single drop in a backyard swimming pool (the equivalent of about 1 part per billion) is more than enough to cause permanent damage. In humans, mercury may cause tremors, problems with vision, and damage to the central nervous system. Studies also reveal developmental problems in wildlife.
Check out this resource for information about fish consumption in the Bay. Though several types of fish, especially those higher up on the food-chain, pose a risk to regular consumers, a variety of alternatives are available at most grocery stores that are “mercury-safe.” Check out the Monterey Bay Aquarium Seafood Watch Guide for more information.
2) PCBs. “P-C-Whats?,” you ask. PCBs, or Polychlorinated Biphenyls (if you want more of a mouthful), are chlorine-impregnated oils which were once widely used in industrial applications for heat transfer and coolant, and in carbonless copy paper, among other uses. While the production of PCBs was banned by Congress in 1979 when people found out how bad they were, they are still used today in electrical transformers.
PCBs represent what are known as “legacy pollutants”—contaminants that were released into the land, air and water from past industrial activities (sometimes many decades ago), that still have a negative impact today.
In the Bay, most PCBs are found in the bottom sediment and travel the same path as mercury—first accumulating at the base of the food chain, and then passing through larger and larger animals until eventually getting into our own diet.
High levels of PCBs specifically harm the liver, digestive tract, and nerves, and can also affect development and reproduction, and the immune system. Unsurprisingly, they have also been found to cause cancer.
3) Pesticides. Pesticides are marketed to suggest that they target and kill specific “pests.” Unfortunately, the actual footprint pesticides have tends to be much, MUCH larger than you might think.
Bugs that eat pesticide-covered plants can become food for other insects and other animals, causing direct harm to many well-loved Bay Area critters like shorebirds and seals. When it rains, pesticides are often washed off plants and properties, and transported into urban creeks and the ocean, where they begin to take immediate effect. BayKeeper reports that only 91 out of the 100,000+ chemicals—including many chemicals used in pesticides—that have been approved for use in the United States over the past 30 years, are regulated.
Luckily a lot of progress has been made to reduce the use of harmful chemicals in pesticides, but, commonly used pesticides including fipronil and imidacloprid are still in use—even the spot-on flea control which can be so useful for getting rid of fleas and ticks on our pets can be a source of water pollution!
4) Trash. This is the pollutant we are all most familiar with—so we’ll keep it short. Trash affects our waters when animals mistake it for food, and when it traps and ensnares them. It presents an added stress on the aquatic community, and an eye-sore for everyone involved. One way to avoid water pollution is to properly manage your waste bins at home. The quickest way (aside from flat out littering) to cause a trash problem is by overfilling your receptacles. Keeping your trash and recyclables properly sorted and ensuring your bins aren’t overflowing on pick-up day is a sure bet to cleaner streets. You can also go the extra mile and reduce your use of trash-making materials like single-use foodware (i.e., paper plates and napkins), and perhaps even join a local cleanup event. When it rains, that debris will flow to the nearest storm drain, which discharges into the nearest creek, and flows right to the Bay or ocean.
Pollution Solutions!!
While there is no one fix to the stormwater pollution problems we have in San Mateo County, there are some small changes we can make that will have a big impact. Small things like minimizing our pesticide usage, picking up after our pets, properly disposing of our trash, and having conversations about this topic with friends, neighbors and families is a terrific start!
The other thing we can do to reduce stormwater pollution is to reduce the flow of water entering the storm system when it rains. Less water in the system helps reduce the amount of runoff-related pollutants entering our waterways. As residents, you can help by installing rain barrels/cisterns or rain gardens on your property. These “rain-saving” solutions can reduce your runoff footprint and protect our precious water resources. As a county, plans are already underway to implement larger green infrastructure projects like bioretention areas, where greater volumes of water can be collected and filtered through specially designed landscaped areas. Fun Fact: as water moves through the soil, it is naturally filtered by mircroogramisms and plants!
If you’re curious about local green infrastructure projects, you can check our article & blog on green infrastructure, and get updates by signing up for our newsletter!
Let’s continue the conversation.
It’s up to all of us to prevent stormwater pollution, and the time for action is now! Be sure to send us your thoughts at info@flowstobay.org, follow us on Facebook, and look out for our monthly blogs!
