Photo courtesy of KDNK

Oil and gas companies reported about 90 spills last year in heavily-drilled Garfield County, Colorado. Many of the leaks happened on private properties leased to drilling companies, said Ed Williams, a reporter at community radio station KDNK.

But when unsafe levels of dangerous chemicals like arsenic and benzene contaminated the land, landowners were sometimes left in the dark, Williams found.

While companies are legally required to notify landowners about spills, state spill reports don’t require them to document the property owner’s name. That’s made it difficult for regulators to enforce the law.

To nail down the story, Williams used online databases from the state – which he cleaned and analyzed in Excel – and a good amount of trial and error.

Listen to Williams’ story here. He also recorded a short “Behind the Story” piece for IRE: