Runoff Pollution: Causes And Effects Of This Environmental Crisis

Runoff pollution is one of the most harmful sources of pollution to bodies of water, and it often starts in the urban and suburban neighbourhoods where people live. Runoff pollution is caused by rainfall or snowmelt that runs off impervious surfaces like buildings, roads, or parking lots and into waterways, picking up and carrying various pollutants along the way. These pollutants include bacteria, chemicals, oil, sediment, debris, and nutrients that spur algal blooms, which can cause low oxygen levels and harm aquatic life and human health.

Rain and snowmelt

The impact of runoff pollution from rain and snowmelt is exacerbated in areas with a high proportion of hard surfaces. In these locations, the water has limited opportunities to evaporate or soak into the ground, where natural filtration could occur. Instead, nearly 100% of the rainwater or snowmelt on hard surfaces becomes runoff, carrying pollutants that adversely affect water quality and aquatic life.

The consequences of this type of pollution are far-reaching. For instance, the eroded dirt carried by the runoff can smother the aquatic habitats of oysters and other species, while the increased nutrients in the water spur algal blooms that deplete oxygen levels, leading to fish kills. The bacteria and pathogens present in the runoff can also pose serious health risks to humans and wildlife, compromising water sources for drinking, recreation, and shellfish harvesting.

To mitigate the effects of rain and snowmelt runoff pollution, several strategies can be employed. Implementing "green infrastructure" in urban and suburban areas is one promising solution. This involves integrating natural spaces, such as rain gardens, and using permeable pavements that allow water to penetrate and be absorbed into the soil, reducing the volume of runoff. Citizens can also play a role by adopting simple habits like composting grass clippings and leaves, properly disposing of hazardous waste, maintaining vehicles to prevent fluid leaks, and picking up and properly disposing of pet waste.

Additionally, rainwater harvesting methods, such as using rain barrels or cisterns to collect runoff from roofs, can help reduce the amount of rainwater or snowmelt that becomes runoff. This harvested rainwater can then be reused for gardening or other suitable applications, reducing the demand for treated water. By combining large-scale infrastructure changes with individual actions, communities can effectively reduce the impact of rain and snowmelt runoff pollution on their local environments and water sources.

Contaminants and sources

Runoff pollution is caused by rainfall or snowmelt that moves over and through the ground and impervious surfaces, such as buildings, roads, or parking lots, and drains into waterways. This water picks up and carries various contaminants, including:

• Pet waste
• Pesticides
• Fertilizer
• Oil and other chemicals
• Bacteria and pathogens
• Sediment and debris
• Nutrients

These contaminants can come from a variety of sources, including residential, commercial, agricultural, and construction sites. For example, pet waste and lawn fertilizer can contribute to runoff pollution, as can leaking septic tanks and sewer lines. In addition, poorly protected construction sites, agricultural fields, roadways, and suburban gardens can be major sources of sediment that is eroded and transported by runoff.

The contaminants carried by runoff can have significant impacts on water quality and the environment. For instance, bacteria and pathogens can pose serious health risks to humans, pets, and wildlife, and nutrients can spur algal blooms that reduce oxygen levels and harm aquatic life.

To reduce runoff pollution, it is important to implement strategies that slow down and absorb the polluted water, such as creating green infrastructure and using permeable surfaces that allow water to penetrate and be absorbed into the soil.

Effects on wildlife and humans

Runoff pollution has a detrimental impact on both wildlife and humans. The effects on wildlife include habitat loss and direct harm from pollutants. For instance, in Washington, Orca whales, two species of salmon, and bull trout are threatened with extinction due to habitat loss and stormwater pollution. Runoff pollution also endangers aquatic life, including fish, and smothers the aquatic homes of oysters and other creatures. The blocked sunlight and increased algae blooms caused by runoff pollution can kill fish and other species.

Humans who rely on well water or live or work near areas of runoff pollution are at risk of harm from contamination. This includes farm workers and residents of nearby communities, who may be exposed to agricultural runoff containing fertilizers, pesticides, and animal waste. Contaminated drinking water can cause various illnesses, including cholera, giardia, and typhoid, and can be especially dangerous for young infants, who are at risk of developing "blue baby" syndrome, a potentially fatal condition caused by high levels of nitrates disrupting oxygen flow in the blood.

Additionally, runoff pollution can lead to beach closures due to bacteria, viruses, and other pathogens from pet and livestock waste, as well as failing septic systems. It can also contribute to flooding, erosion, and property damage, as the increased volume of water runs off hard surfaces during heavy rains.

The effects of runoff pollution are far-reaching and long-lasting, and it is important to address this issue to protect both human health and the environment. Implementing "green infrastructure" solutions, such as planting rain gardens, attaching downspouts to rain barrels, and replacing old pavement with pervious pavement, can help reduce the impact of runoff pollution on both wildlife and humans.

Green infrastructure solutions

Runoff pollution is caused by rainwater and snowmelt that collect contaminants as they run off hard surfaces like streets, parking lots, and lawns. These contaminants include pet waste, pesticides, fertilizer, oil, and other harmful substances. This polluted runoff ends up in local waterways, negatively impacting water quality, aquatic life, and even drinking water sources.

To address this issue, implementing green infrastructure solutions can be highly effective. Green infrastructure aims to manage water in a more sustainable and natural way, reducing the amount of polluted runoff. Here are some specific green infrastructure strategies that can be employed:

Rain Gardens and Natural Spaces

Planting rain gardens and creating natural spaces in low-lying areas can help capture and absorb rainwater, preventing it from becoming polluted runoff. These gardens act as natural filters, allowing water to soak into the ground and be cleaned before it reaches local waterways.

Rain Barrels and Cisterns

Attaching downspouts to rain barrels or cisterns is a simple and affordable way to collect rainwater. This captured water can then be used for watering gardens and lawns, reducing the need for treated water. Rain barrels help slow down and divert the flow of rainwater, preventing it from becoming polluted runoff.

Permeable Pavement

Replacing old pavement with permeable or porous pavement allows water to penetrate and be absorbed into the soil. This reduces the amount of runoff and provides a natural filtration process. Permeable pavement can also lower construction costs by reducing the need for conventional drainage systems.

Green Roofs

Green roofs involve planting vegetation directly on top of building roofs. The plants and soil capture and slow down rainwater, preventing it from becoming runoff. Green roofs help reduce the proportion of hard surfaces in urban areas, which are major contributors to runoff pollution.

Streamside Forests

Planting trees and shrubs along streams has multiple benefits. These streamside forests prevent pollution from entering waterways, stabilize stream banks, provide habitat for aquatic life, and keep streams cool. They contribute to natural filtration and improve the stream's ability to cleanse itself of pollution.

Vegetated Roadside Plantings

Incorporating vegetation along roadsides helps capture, filter, and reduce stormwater runoff. This strategy mimics natural hydrological processes, turning rainfall into a resource instead of waste. It also provides environmental benefits, such as improved air quality and reduced urban heat island effects.

By implementing these green infrastructure solutions, communities can effectively reduce runoff pollution, improve water quality, enhance local ecosystems, and create more resilient and aesthetically pleasing neighbourhoods.

Preventing runoff pollution

Runoff pollution is caused by rainwater and snowmelt that wash off various impermeable surfaces, such as streets, parking lots, and rooftops, picking up contaminants along the way. This polluted water then flows into local waterways, causing significant environmental and economic harm.

To prevent runoff pollution, several measures can be implemented:

Permeable Surfaces and Landscaping:

• Install permeable surfaces like interlocking stone pavers or dry wells that allow water to penetrate and be absorbed back into the soil, reducing runoff.
• Implement landscaping projects that slow down, catch, or filter rainwater or snowmelt.
• Use compost and soil with high organic content, which retains more water and acts as a natural filter for pollutants.
• Reduce impervious surfaces, such as concrete or asphalt, and increase vegetated land cover with native, drought-resistant plants.

Proper Waste Disposal and Pollution Reduction:

• Properly dispose of products and waste, keeping them out of storm drains and waterways.
• Pick up after pets and prevent animal waste from washing into nearby waterways.
• Minimize the use of fertilizers, pesticides, and other chemicals that can be washed away and pollute water sources.
• Regularly maintain septic systems to prevent failures that could lead to pollution.

Agricultural and Regenerative Practices:

• Farmers can adopt regenerative agriculture practices, such as impact investment projects, to reduce polluted runoff from agricultural lands.
• Reduce the use of fertilizers and pesticides in farming and gardening practices.

Community Initiatives:

• Educate communities about the impacts of runoff pollution and provide resources to help manage stormwater.
• Implement green infrastructure initiatives, such as soaking up rainwater through natural sponges like soil and plants, to prevent water pollution and reduce flooding.

Frequently asked questions