Advocates for fracking in the United States will be the first to tell you that the process of extracting oil or gas from deep underground is very safe – or at least safer than the other energy sources. But as we are increasingly learning, the process of fracking is not at all safe for our environment, and is in fact leaking into natural wildlife and water sources at a far greater rate than we ever thought.

Fracking is the act of forcing liquid at high pressure into the ground in order to expose pockets of oil or gas underneath the earth’s surface. Many believe that fracking can and does cause earth tremors which can destroy homes and kill people.

But earth tremors aside, a new study published in Popular Science found that fracking wells were subject to surface leaks an alarming amount, raising questions about the environmental effect of this oil-drilling process.

The study watched more than 31 thousand fracking wells in four U.S. states for a period of nine years. During that time, they observed 6,648 spills in just these four states – or two spills a day.

The study also discovered that the frequency of these spills may be going on unnoticed by the companies maintaining the wells as older wells are often less closely monitored. This means that any data being provided by the corporations is likely completely inaccurate.

Watch.