Pollution
Pollution
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Understanding Pollution Sources
Salem Sound Coastwatch is committed to increasing the public’s knowledge of the threats to the Salem Sound watershed, fostering responsible stormwater management, and promoting citizens’ and municipalities’ understanding of their role in restoring and protecting the watershed and Salem Sound.
In order to reduce pollution, we need to understand its many sources.
Point source pollution is defined as pollutant discharge from a single identifiable source, such as a sewer outfall or industrial plant. Much progress has been made in identifying and controlling point source pollution in the past decades. The focus has now shifted to non-point source pollution.
Non-point source pollution is the #1 threat to coastal water quality. When it rains, water needs somewhere to go. In a natural system, most of the rain is absorbed by vegetation and soils. But when land gets paved over, the water runs downhill into our rivers and ocean carrying pollutants. This is called stormwater runoff. Stormwater discharge causes many problems, such as:
- Eutrophication of our streams and ponds
- Sedimentation of fish spawning areas
- Reduced water in our streams because less water is going into the ground
- Flooding of low-lying areas
- Bacterial pollution at our beaches and in shellfish beds
Drains to the Ocean
As stormwater travels downhill over paved (or impervious) surfaces, it picks up fertilizers from yards, oil and chemicals from cars and streets, animal waste, and sediments.
Bacteria from pet waste and malfunctioning sewerage infrastructure contaminates our beaches and waterbodies. While bacteria are part of the normal intestinal microbiota of humans and animals, they are also pathogens that are responsible for serious infections in humans. Bacterial pollution results in closures of beaches and shellfish beds.
Bacterial contamination is a major problem in many water bodies across the United States. Some common strains of bacteria that you may have heard of in humans are Escherichia coli (E. coli), Enterococci, and fecal coliform. They are the indicator bacteria used in testing water to see if it has been polluted by a human or animal source.
After heavy precipitation, many outdated combined sewer systems that are designed to handle both sewage and stormwater are overloaded. As a result, bacteria-laden water flows from outfall pipes and into our waterways where they then cause infectious diseases. Stormwater runoff also causes bacterial pollution at our beaches and shorelines that seeps into shellfish beds, contaminating the seafloor and making shellfish inedible. Finally, unmaintained or overloaded septic systems will leak waste and pollute the surrounding groundwater, eventually infiltrating into the larger watershed.
Total Maximum Daily Loads (TMDL) is a measurement used to fight pathogens in our water by establishing a maximum amount of bacteria that can be discharged to a waterbody from both point and non-point sources, with the goal of improving overall water quality.
Additionally, Salem Sound itself is a No Discharge Area, meaning that boating vessels cannot, under any circumstances, release their blackwater (human waste) or graywater (sinks, showers/baths, washing machines, dishwashers) directly into the open ocean.
Action: Always pick up after your pets. Maintain your septic tank system regularly. If you own a boat, only dispose of wastewater at designated pumpout sites.
Nutrients like phosphorus and nitrogen are required for plants to grow. In fact, a healthy ecosystem needs these elements and other nutrients for plants and animals to survive. But when there are too many nutrients and minerals present in the water, they can have a negative impact on marine and aquatic environments.
This process is known as eutrophication, where lakes, ponds, and waterways have an over abundance of nutrients. Eutrophication can increase with human development due to fertilizer run off from lawns. The most common result of eutrophication are algal blooms, due to excessive growth. Algal blooms block sunlight from reaching eelgrass on the bottom of Salem Sound, which reduces their already fragmented footprint.
As plants take in more of these newly available nutrients to grow, the amount of plant life expands to an unsustainable level. This then leads to a mass die-off of the plants, which reduces the amount of dissolved oxygen present in the water as the organisms decompose. The habitat is said to anoxic, or oxygen-depleted, and conditions overall have degraded. A feedback loop occurs with phosphorus in the absence of oxygen. More phosphorus is produced to counter the lack of oxygen, which is that taken up by marine plants, and the cycle of eutrophication starts all over again.
Marine animals require dissolved oxygen to survive, so the anoxic conditions created by nutrient enrichment and eutrophication always harms them. The water quality decreases and becomes inhospitable to life. Eutrophic waters are more likely to have algal blooms, smell badly to humans, and have high turbidity or less clarity in the water. SSCW monitors bacterial levels including in Beverly’s Lawrence Brook and Danvers’ Frost Fish Brook.
Action: Compost yard waste. Do not sweep leaves and grass clippings into the street. Decaying plant debris adds phosphorus and other nutrients to water. Use less fertilizer, pick up pet waste, or build a rain garden by planting native trees and shrubs to absorb water also remove nutrients. Rain gardens along Commercial Street in Salem absorb pollutants that are washed off the street by rain and snow, intercepting them before they reach the North River.
Perhaps the most obvious problem facing our oceans today is the increasing amount of trash that makes its way into our waterways. Plastic makes its way into our oceans in a variety of ways. About 20% of it comes from goods lost from boats: accidental loss of fishing tackle and other recreational gear, massive shipping containers carrying millions of plastic items washed overboard during severe storms, litter from pleasure boats, or illegal dumping of unwanted goods. Beachgoer debris is also a contributor. The other 80% is swept in from land. Just as fertilizer, detergent, and pesticide pollution finds their way into our waters, so too are plastic items washing into our oceans.
The US alone consumes 500 million straws each day – enough to circle the Earth more than 2.5 times per day. That adds up to 182 billion straws a year. When mistaken for food by marine life and swallowed, straws can cause injury or even death. Drink straws, as well as coffee stirrers, cocktail straws, and bendy straws, gradually break down into microplastics whose toxins leach into the water. One way you can cut back on the impacts that straws have is by using a reusable bottle with a paper, stainless steel, glass, or bamboo reusable straws instead of single-use plastic straws and bottles.
Action: Pick up any trash you see along the roads, sidewalks, and shoreline using protective gloves, grabbers, and buckets. Volunteer for a beach cleanup with Salem Sound Coastwatch.
Oil and chemicals from vehicles and boats are large contributors to water pollution. Engines can leak oil while sitting in driveways and marinas and make their way to the ocean through storm runoff and non-point pollution.
Today, more federal and state laws exist that prevent companies from polluting the water, but individual residents still contribute their share of these pollutants. Regularly maintaining your vehicles is the best way to prevent accidental discharge of pollutants while they are idle.
Disposing of used motor oil and batteries at recycle centers prevents oil from entering the ecosystem and the metals contained in batteries are properly processed from leeching toxins into water.
Wash your car in your yard using biodegradable and non-phosphate detergents so that graywater infiltrates into the ground or use a commercial car wash that treats or recycles its wastewater. If you have a septic system, keep it working properly and have it pumped at least every 3 years.
Action: Store and dispose of chemicals properly. Most importantly, DO NOT DISCARD CHEMICALS DOWN THE STORM DRAIN!
Deicers are common pollutants that are washed into watersheds and the ocean, so great care must be taken to use the least amount necessary. As deicers melt, up to 55% of the chlorine contained within becomes part of stormwater runoff, entering waterways where it can create toxic conditions for aquatic life and our drinking water.
Some other deicer options you can use are abrasives like sand, sawdust, clean clay kitty litter, or fireplace/stove ash. The most common deicer, rock salt, is the most toxic. Although no deicer is completely environmentally or pet friendly, read the label carefully before you buy to ensure that you are getting the lowest possible chloride content.
Abrasives get tracked into our homes and wash into watersheds, eventually entering our rivers and streams causing sedimentation problems. Lay a wooden walkway over snow and ice or use sand where a walkway is not feasible. Be sure to sweep it up in the spring before it washes into watersheds. Sweep up salt and sand on your walkways after snowmelt.
Calcium magnesium acetate (CMA) is biodegradable and far less corrosive than traditional chloride-based salts. It’s generally thought to be 10 times less corrosive than rock salt and when used as directed is safe for use around humans, pets, plants, and turf. CMA contains dolomitic limestone and acetic acid (common vinegar) and although costly, up to 55% more than road salt, it is a wise choice for use during relatively small applications needed around homes because it is salt-free.
Action: Apply deicers evenly using a broadcast spreader instead of scattering by the handful and select a colored product that can be easily seen on the ground to prevent overapplication.