Vegetation restoration at abandoned oil and gas well sites on the Colorado Plateau varies

“The Colorado Plateau is an ecologically diverse region used for energy development, agriculture and recreation, and includes approximately 30 national parks,” said Miguel Villarreal, a U.S. Geological Survey scientist and author of the study. “Understanding the factors that promote successful vegetation restoration is critical for resource managers to make informed decisions about this economically and ecologically important region.”

There are more than 26,000 abandoned oil and gas wells and 63,000 active wells on the Colorado Plateau. When these wells are plugged and abandoned, they must be revegetated to limit soil erosion, restore livestock feed, and provide habitat for wildlife. Much of the Colorado Plateau is a water-limited ecosystem, which makes revegetation difficult.

Using satellite, soil and climate data, scientists with the U.S. Geological Survey studied vegetation recovery over three to six years at 365 well sites in parts of Utah, Colorado and New Mexico that were drilled in 1985 or later and abandoned in 1997 or later. The area of ​​the soil surface covered by plants (called vegetation cover) at abandoned well sites was looked at from top to bottom and compared to vegetation cover at nearby reference sites without wells to determine relative vegetation recovery. This is a scientific method developed last year by scientists from the United States Geological Survey.

The extent of vegetation restoration varied widely among sites. After five years of restoration, the well sites had an average vegetation cover of 36% of the reference sites. About half of the well sites in the study had less than 26% of the reference sites. About a third of the well sites had more than 50% of the reference sites. The USGS has conducted several studies to better understand which restoration techniques work, which don’t, and where.

The differences in vegetation recovery at abandoned well sites may be due to differences in humidity from year to year. Relatively wet years, such as 2005, 2008, and 2011, had relatively high rates of vegetation recovery. The driest year in the study, 2002, had lower rates of vegetation recovery.

The type of plant community in which the abandoned well site is located is also important. Abandoned well sites in shrublands and pine-juniper forests generally had lower rates of vegetation recovery, with vegetation recovery in these systems being about half that of prairie well sites.

The results also showed that some non-native species, such as brome grass and Russian thistle, can colonize abandoned well sites. While these species contribute to vegetation cover, they are not as popular as native species.

The Colorado Plateau covers approximately 131,000 square miles and is located in parts of Arizona, Utah, Colorado, and New Mexico. The plateau is an ecologically diverse region that includes grasslands, shrublands, woodlands, and forests.

“Landsat imagery and other observational data can help identify sites at risk for poor recovery and aid in developing strategies to improve successful reclamation following oil and gas development on the Colorado Plateau,” Villareal said.