Stormwater Effects

Why Stormwater Is a Problem

• Stormwater runoff poses a problem to humans and the environment, largely due to the impervious alterations that humans have made to the environment. Human developments such as roads and sidewalks prevent water from being absorbed into the ground. This means that large volumes of water travel along the ground and through drainage systems, collecting debris and chemicals along the way and transporting them to water systems where they can affect water supplies and the environment.

Impact on Humans

• Stormwater can have a negative effect on human health by carrying chemicals and bacteria into the water that people drink and swim in. Another effect on humans is the increased costs that are incurred by water supplies requiring further treatment and reservoirs requiring the removal of excess sediment carried by stormwater. Pollutants in water that have been carried there by stormwater can also be harmful to people when they are swallowed or come into contact with skin when swimming.

Environmental Impact

• Stormwater carries material that is capable of affecting the environment through erosion, depositing sediment and causing damage to ecosystems. Drainage pipes direct large amounts of fast-moving rainwater to rivers; the force of this water causes the banks and beds of streams and rivers to erode, affecting natural river systems. The sediment that is transported by stormwater and the erosion that it causes have a negative impact on the environment: Plants have difficultly growing in water that is full of sediment, and aquatic animals can be suffocated by the material. Excess amounts of sediment can also cause some aquatic ecosystems to be destroyed completely.

Effects on Animals

• Stormwater collects litter which can be harmful to aquatic wildlife when it is transported to rivers. For example, plastic bags can suffocate animals, and they can be caught in the plastic rings that are used for holding cans together. Wildlife may also attempt to eat some larger items of debris and choke as a result.

  Stormwater can also contain substances that are harmful to animals, such as solvents, oil and pesticides. These chemicals can affect land animals and aquatic animals by poisoning the environment and food within it. Fertilizers can also enter aquatic ecosystems through stormwater. This can increase algae growth which reduces oxygen levels in the water and causes other aquatic life to die. Large amounts of chemicals, carried into aquatic ecosystems by stormwater, can also cause deformities in wildlife such as frogs.