Oil spills in Colorado increased by 17 percent from 2020 to 2021, from 349 to 408. Of these spills, 50 percent were in Weld County, which has had the highest percentage of spills in the state each year. These spills impacted communities, with at least 274 occurring within half a mile of a water well. The number could be higher as only around a quarter of all spills included information on their proximity to a water well. Similarly, at least 117 spills occurred within half a mile of an occupied building, but only around half of spills included information on their proximity to an occupied building. Finally, at least 243 spills were within half a mile of surface water, but only around 70 percent of spills included information on their proximity to surface water.  

Colorado had around 1200 fewer wells operating in 2021 compared to 2020, meaning there was a higher rate of spills per well in 2021. However, oil production was down 20 percent from its pre-pandemic level, while spills were down almost 40 percent compared to 2019, indicating possibly substantial progress in reducing the state’s spill rate.