Environmental impact of hydraulic fracturing

Hydraulic fracturing has the potential to cause fugitive methane emissions, air emissions, water contamination, and noise pollution. Water and air pollution are the biggest risks to human health from hydraulic fracturing. Research is underway to determine if human health has been affected, and adherence to regulation and safety procedures is required to avoid negative impacts.

Hydraulic fracturing fluids include proppants and other substances, which may include toxic chemicals. In the United States, such additives may be treated as trade secrets by companies who use them. Lack of knowledge about specific chemicals has complicated efforts to develop risk management policies and to study health effects. In other jurisdictions, such as the United Kingdom, these chemicals must be made public and their applications are required to be nonhazardous.

Water usage by hydraulic fracturing can be a problem in areas that experience water shortage. Surface water may be contaminated through spillage and improperly built and maintained waste pits, in jurisdictions where these are permitted. Further, ground water can be contaminated if fluid is able to escape during fracking. Produced water, the water that returns to the surface after fracking, is managed by underground injection, municipal and commercial wastewater treatment, and reuse in future wells. There is potential for methane to leak into ground water and the air, though escape of methane is a bigger problem in older wells than in those built under more recent legislation.

Hydraulic fracturing causes induced seismicity called microseismic events or microearthquakes. The magnitude of these events is too small to be detected at the surface, being of magnitude M-3 to M-1 usually. However, fluid disposal wells (which are often used in the US to dispose of polluted waste from several industries) have been responsible for earthquakes up to 5.6M in Oklahoma and other states.

...
Wikipedia