An oil and gas watchdog group is raising alarms about contamination of the Pecos River, a rare water source in the arid oil and gas fields of West Texas.

For the seventh week in a row, highly salty wastewater has been flowing into the river, leaving oily streaks over a quarter mile long in the riverbed and leaving crusts of salt up to three inches thick along its banks, according to photos shared by Commission Shift.

State regulators with the Texas Commission on Environmental Quality and the Railroad Commission of Texas have been to the site multiple times but have not identified where the wastewater is coming from. Nearby sources could include a pipeline and nearby inactive wells, according to Commission Shift.

Schuyler Wight, a local rancher, captured photos of the pollution and has urged the Railroad Commission to investigate.

“I know it's a pain to deal with landowners, but we do have some local knowledge that might be helpful every once in a while,” Wight said in a Commission Shift news release.

Julie Range, the organization’s policy manager, said the source must be found and the leak stopped as quickly as possible.

“This leak has filled a section of river with salt that may be laced with heavy metals and other toxic chemicals that should be removed and not be left to flow downstream and harm ecosystems,” Range said.